Pub Date : 2024-06-26DOI: 10.1007/s00775-024-02064-y
Rolf Büssing, Arne Bublitz, Bianka Karge, Mark Brönstrup, Till Strowig, Ingo Ott
Antimicrobial resistance (AMR) has been emerging as a major global health threat and calls for the development of novel drug candidates. Metal complexes have been demonstrating high efficiency as antibacterial agents that differ substantially from the established types of antibiotics in their chemical structures and their mechanism of action. One strategy to exploit this potential is the design of metal-based hybrid organometallics that consist of an established antibiotic and a metal-based warhead that contributes an additional mechanism of action different from that of the parent antibiotic. In this communication, we describe the organometallic hybrid antibiotic 2c, in which the drug metronidazole is connected to a gold(I) N-heterocyclic carbene warhead that inhibits bacterial thioredoxin reductase (TrxR). Metronidazole can be used for the treatment with the obligatory anaerobic pathogen Clostridioides difficile (C. difficile), however, resistance to the drug hampers its clinical success. The gold organometallic conjugate 2c was an efficient inhibitor of TrxR and it was inactive or showed only minor effects against eucaryotic cells and bacteria grown under aerobic conditions. In contrast, a strong antibacterial effect was observed against both metronidazole-sensitive and -resistant strains of C. difficile. This report presents a proof-of-concept that the design of metal-based hybrid antibiotics can be a viable approach to efficiently tackle AMR.
抗菌药耐药性(AMR)已成为全球健康的一大威胁,需要开发新型候选药物。金属复合物作为高效抗菌剂,在化学结构和作用机制上与现有的抗生素有很大不同。利用这一潜力的策略之一是设计金属基混合有机金属,它由一种成熟的抗生素和一种金属基弹头组成,后者具有不同于母体抗生素的额外作用机制。在这篇通讯中,我们介绍了有机金属杂化抗生素 2c,其中的药物甲硝唑与抑制细菌硫代还原酶(TrxR)的 N-杂环碳金(I)弹头相连。甲硝唑可用于治疗强制性厌氧病原体艰难梭菌(C. difficile),但该药物的抗药性阻碍了它在临床上取得成功。金有机金属共轭物 2c 是一种高效的 TrxR 抑制剂,但它对有氧条件下生长的真核细胞和细菌无活性或仅有轻微作用。相反,它对甲硝唑敏感和耐药的艰难梭菌菌株都有很强的抗菌作用。本报告提出了一个概念证明,即设计金属基混合抗生素是有效解决 AMR 的可行方法。
{"title":"An organometallic hybrid antibiotic of metronidazole with a Gold(I) N-Heterocyclic Carbene overcomes metronidazole resistance in Clostridioides difficile.","authors":"Rolf Büssing, Arne Bublitz, Bianka Karge, Mark Brönstrup, Till Strowig, Ingo Ott","doi":"10.1007/s00775-024-02064-y","DOIUrl":"https://doi.org/10.1007/s00775-024-02064-y","url":null,"abstract":"<p><p>Antimicrobial resistance (AMR) has been emerging as a major global health threat and calls for the development of novel drug candidates. Metal complexes have been demonstrating high efficiency as antibacterial agents that differ substantially from the established types of antibiotics in their chemical structures and their mechanism of action. One strategy to exploit this potential is the design of metal-based hybrid organometallics that consist of an established antibiotic and a metal-based warhead that contributes an additional mechanism of action different from that of the parent antibiotic. In this communication, we describe the organometallic hybrid antibiotic 2c, in which the drug metronidazole is connected to a gold(I) N-heterocyclic carbene warhead that inhibits bacterial thioredoxin reductase (TrxR). Metronidazole can be used for the treatment with the obligatory anaerobic pathogen Clostridioides difficile (C. difficile), however, resistance to the drug hampers its clinical success. The gold organometallic conjugate 2c was an efficient inhibitor of TrxR and it was inactive or showed only minor effects against eucaryotic cells and bacteria grown under aerobic conditions. In contrast, a strong antibacterial effect was observed against both metronidazole-sensitive and -resistant strains of C. difficile. This report presents a proof-of-concept that the design of metal-based hybrid antibiotics can be a viable approach to efficiently tackle AMR.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141454502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-26DOI: 10.1007/s00775-024-02063-z
Ahmet Duran Ataş, Zübeyda Akın-Polat, Derya Gül Gülpınar, Neslihan Şahin
Encephalitozoon intestinalis is an opportunistic microsporidian parasite that primarily infects immunocompromised individuals, such as those with HIV/AIDS or undergoing organ transplantation. Leishmaniasis is responsible for parasitic infections, particularly in developing countries. The disease has not been effectively controlled due to the lack of an effective vaccine and affordable treatment options. Current treatment options for E. intestinalis infection and leishmaniasis are limited and often associated with adverse side effects. There is no previous study in the literature on the antimicrosporidial activities of Ag(I)-N-heterocyclic carbene compounds. In this study, the in vitro antimicrosporidial activities of previously synthesized Ag(I)-N-heterocyclic carbene complexes were evaluated using E. intestinalis spores cultured in human renal epithelial cell lines (HEK-293). Inhibition of microsporidian replication was determined by spore counting. In addition, the effects of the compounds on Leishmania major promastigotes were assessed by measuring metabolic activity or cell viability using a tetrazolium reaction. Statistical analysis was performed to determine significant differences between treated and control groups. Our results showed that the growth of E. intestinalis and L. major promastigotes was inhibited by the tested compounds in a concentration-dependent manner. A significant decrease in parasite viability was observed at the highest concentrations. These results suggest that the compounds have potential anti-microsporidial and anti-leishmanial activity. Further research is required to elucidate the underlying mechanisms of action and to evaluate the efficacy of the compounds in animal models or clinical trials.
{"title":"The first evaluation of the in vitro effects of silver(I)-N-heterocyclic carbene complexes on Encephalitozoon intestinalis and Leishmania major promastigotes.","authors":"Ahmet Duran Ataş, Zübeyda Akın-Polat, Derya Gül Gülpınar, Neslihan Şahin","doi":"10.1007/s00775-024-02063-z","DOIUrl":"https://doi.org/10.1007/s00775-024-02063-z","url":null,"abstract":"<p><p>Encephalitozoon intestinalis is an opportunistic microsporidian parasite that primarily infects immunocompromised individuals, such as those with HIV/AIDS or undergoing organ transplantation. Leishmaniasis is responsible for parasitic infections, particularly in developing countries. The disease has not been effectively controlled due to the lack of an effective vaccine and affordable treatment options. Current treatment options for E. intestinalis infection and leishmaniasis are limited and often associated with adverse side effects. There is no previous study in the literature on the antimicrosporidial activities of Ag(I)-N-heterocyclic carbene compounds. In this study, the in vitro antimicrosporidial activities of previously synthesized Ag(I)-N-heterocyclic carbene complexes were evaluated using E. intestinalis spores cultured in human renal epithelial cell lines (HEK-293). Inhibition of microsporidian replication was determined by spore counting. In addition, the effects of the compounds on Leishmania major promastigotes were assessed by measuring metabolic activity or cell viability using a tetrazolium reaction. Statistical analysis was performed to determine significant differences between treated and control groups. Our results showed that the growth of E. intestinalis and L. major promastigotes was inhibited by the tested compounds in a concentration-dependent manner. A significant decrease in parasite viability was observed at the highest concentrations. These results suggest that the compounds have potential anti-microsporidial and anti-leishmanial activity. Further research is required to elucidate the underlying mechanisms of action and to evaluate the efficacy of the compounds in animal models or clinical trials.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141449248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-05-16DOI: 10.1007/s00775-024-02052-2
Mohammed Zain Aldin, Guillermo Zaragoza, Eva Choquenet, Guillaume Blampain, Gilles Berger, Lionel Delaude
Five cationic ruthenium-arene complexes with the generic formula [Ru(SAc)(S2C·NHC)(p-cymene)](PF6) (5a-e) were prepared in almost quantitative yields using a straightforward one-pot, two-step experimental procedure starting from [RuCl2(p-cymene)]2, an imidazol(in)ium-2-dithiocarboxylate (NHC·CS2) zwitterion, KSAc, and KPF6. These half-sandwich compounds were fully characterized by various analytical techniques and the molecular structures of two of them were solved by X-ray diffraction analysis, which revealed the existence of an intramolecular chalcogen bond between the oxygen atom of the thioacetate ligand and a proximal sulfur atom of the dithiocarboxylate unit. DFT calculations showed that the C=S…O charge transfer amounted to 2.4 kcal mol-1. The dissolution of [Ru(SAc)(S2C·IMes)(p-cymene)](PF6) (5a) in moist DMSO-d6 at room temperature did not cause the dissociation of its sulfur ligands. Instead, p-cymene was slowly released to afford the 12-electron [Ru(SAc)(S2C·IMes)]+ cation that could be detected by mass spectrometry. Monitoring the solvolysis process by 1H NMR spectroscopy showed that more than 22 days were needed to fully decompose the starting ruthenium-arene complex. Compounds 5a-e exhibited a high antiproliferative activity against human glioma Hs683 and human lung carcinoma A549 cancer cells. In particular, the IMes derivative (5a) was the most potent compound of the series, achieving toxicities similar to those displayed by marketed platinum drugs.
{"title":"Synthesis, characterization, and biological activity of cationic ruthenium-arene complexes with sulfur ligands.","authors":"Mohammed Zain Aldin, Guillermo Zaragoza, Eva Choquenet, Guillaume Blampain, Gilles Berger, Lionel Delaude","doi":"10.1007/s00775-024-02052-2","DOIUrl":"10.1007/s00775-024-02052-2","url":null,"abstract":"<p><p>Five cationic ruthenium-arene complexes with the generic formula [Ru(SAc)(S<sub>2</sub>C·NHC)(p-cymene)](PF<sub>6</sub>) (5a-e) were prepared in almost quantitative yields using a straightforward one-pot, two-step experimental procedure starting from [RuCl<sub>2</sub>(p-cymene)]<sub>2</sub>, an imidazol(in)ium-2-dithiocarboxylate (NHC·CS<sub>2</sub>) zwitterion, KSAc, and KPF<sub>6</sub>. These half-sandwich compounds were fully characterized by various analytical techniques and the molecular structures of two of them were solved by X-ray diffraction analysis, which revealed the existence of an intramolecular chalcogen bond between the oxygen atom of the thioacetate ligand and a proximal sulfur atom of the dithiocarboxylate unit. DFT calculations showed that the C=S<sup>…</sup>O charge transfer amounted to 2.4 kcal mol<sup>-1</sup>. The dissolution of [Ru(SAc)(S<sub>2</sub>C·IMes)(p-cymene)](PF<sub>6</sub>) (5a) in moist DMSO-d<sub>6</sub> at room temperature did not cause the dissociation of its sulfur ligands. Instead, p-cymene was slowly released to afford the 12-electron [Ru(SAc)(S<sub>2</sub>C·IMes)]<sup>+</sup> cation that could be detected by mass spectrometry. Monitoring the solvolysis process by <sup>1</sup>H NMR spectroscopy showed that more than 22 days were needed to fully decompose the starting ruthenium-arene complex. Compounds 5a-e exhibited a high antiproliferative activity against human glioma Hs683 and human lung carcinoma A549 cancer cells. In particular, the IMes derivative (5a) was the most potent compound of the series, achieving toxicities similar to those displayed by marketed platinum drugs.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":3.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140943043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-05-23DOI: 10.1007/s00775-024-02058-w
Narmada Behera, Gargee Bhattacharyya, Satyabrat Behera, Rabindra K Behera
Ferritins are multimeric nanocage proteins that sequester/concentrate excess of free iron and catalytically synthesize a hydrated ferric oxyhydroxide bio-mineral. Besides functioning as the primary intracellular iron storehouses, these supramolecular assemblies also oversee the controlled release of iron to meet physiologic demands. By virtue of the reducing nature of the cytosol, reductive dissolution of ferritin-iron bio-mineral by physiologic reducing agents might be a probable pathway operating in vivo. Herein, to explore this reductive iron-release pathway, a series of quinone analogs differing in size, position/nature of substituents and redox potentials were employed to relay electrons from physiologic reducing agent, NADH, to the ferritin core. Quinones are well known natural electron/proton mediators capable of facilitating both 1/2 electron transfer processes and have been implicated in iron/nutrient acquisition in plants and energy transduction. Our findings on the structure-reactivity of quinone mediators highlight that iron release from ferritin is dictated by electron-relay capability (dependent on E1/2 values) of quinones, their molecular structure (i.e., the presence of iron-chelation sites and the propensity for H-bonding) and the type/amount of reactive oxygen species (ROS) they generate in situ. Juglone/Plumbagin released maximum iron due to their intermediate E1/2 values, presence of iron chelation sites, the ability to inhibit in situ generation of H2O2 and form intramolecular H-bonding (possibly promotes semiquinone formation). This study may strengthen our understanding of the ferritin-iron-release process and their significance in bioenergetics/O2-based cellular metabolism/toxicity while providing insights on microbial/plant iron acquisition and the dynamic host-pathogen interactions.
铁蛋白是一种多聚体纳米笼蛋白,它能螯合/浓缩过量的游离铁,并催化合成水合氢氧化铁生物矿物质。除了作为细胞内主要的铁储存库,这些超分子组装体还负责控制铁的释放,以满足生理需求。由于细胞液具有还原性,铁蛋白-铁生物矿物质被生理还原剂还原溶解可能是体内运行的一个途径。为了探索这种还原性铁释放途径,我们采用了一系列在大小、取代基位置/性质和氧化还原电位方面不同的醌类似物,将电子从生理还原剂 NADH 传递到铁蛋白核心。醌类化合物是众所周知的天然电子/质子介质,能够促进 1/2 电子转移过程,并与植物的铁/养分获取和能量转移有关。我们对醌介质的结构-反应性的研究结果表明,铁蛋白中铁的释放取决于醌的电子中继能力(取决于 E1/2 值)、其分子结构(即铁螯合位点的存在和 H 键的倾向)以及它们在原位产生的活性氧(ROS)的类型/数量。Juglone/Plumbagin 释放的铁最多,这是因为它们具有中间 E1/2 值、存在铁螯合位点、能够抑制 H2O2 的原位生成并形成分子内 H 键(可能促进半醌的形成)。这项研究可加强我们对铁蛋白-铁释放过程及其在生物能/基于氧气的细胞代谢/毒性中的意义的了解,同时为微生物/植物铁的获取以及宿主与病原体之间的动态相互作用提供启示。
{"title":"Iron mobilization from intact ferritin: effect of differential redox activity of quinone derivatives with NADH/O<sub>2</sub> and in situ-generated ROS.","authors":"Narmada Behera, Gargee Bhattacharyya, Satyabrat Behera, Rabindra K Behera","doi":"10.1007/s00775-024-02058-w","DOIUrl":"10.1007/s00775-024-02058-w","url":null,"abstract":"<p><p>Ferritins are multimeric nanocage proteins that sequester/concentrate excess of free iron and catalytically synthesize a hydrated ferric oxyhydroxide bio-mineral. Besides functioning as the primary intracellular iron storehouses, these supramolecular assemblies also oversee the controlled release of iron to meet physiologic demands. By virtue of the reducing nature of the cytosol, reductive dissolution of ferritin-iron bio-mineral by physiologic reducing agents might be a probable pathway operating in vivo. Herein, to explore this reductive iron-release pathway, a series of quinone analogs differing in size, position/nature of substituents and redox potentials were employed to relay electrons from physiologic reducing agent, NADH, to the ferritin core. Quinones are well known natural electron/proton mediators capable of facilitating both 1/2 electron transfer processes and have been implicated in iron/nutrient acquisition in plants and energy transduction. Our findings on the structure-reactivity of quinone mediators highlight that iron release from ferritin is dictated by electron-relay capability (dependent on E<sub>1/2</sub> values) of quinones, their molecular structure (i.e., the presence of iron-chelation sites and the propensity for H-bonding) and the type/amount of reactive oxygen species (ROS) they generate in situ. Juglone/Plumbagin released maximum iron due to their intermediate E<sub>1/2</sub> values, presence of iron chelation sites, the ability to inhibit in situ generation of H<sub>2</sub>O<sub>2</sub> and form intramolecular H-bonding (possibly promotes semiquinone formation). This study may strengthen our understanding of the ferritin-iron-release process and their significance in bioenergetics/O<sub>2</sub>-based cellular metabolism/toxicity while providing insights on microbial/plant iron acquisition and the dynamic host-pathogen interactions.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141080148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-05-23DOI: 10.1007/s00775-024-02057-x
Nitai C Giri, Breeanna Mintmier, Manohar Radhakrishnan, Jonathan W Mielke, Jarett Wilcoxen, Partha Basu
Periplasmic nitrate reductase NapA from Campylobacter jejuni (C. jejuni) contains a molybdenum cofactor (Moco) and a 4Fe-4S cluster and catalyzes the reduction of nitrate to nitrite. The reducing equivalent required for the catalysis is transferred from NapC → NapB → NapA. The electron transfer from NapB to NapA occurs through the 4Fe-4S cluster in NapA. C. jejuni NapA has a conserved lysine (K79) between the Mo-cofactor and the 4Fe-4S cluster. K79 forms H-bonding interactions with the 4Fe-4S cluster and connects the latter with the Moco via an H-bonding network. Thus, it is conceivable that K79 could play an important role in the intramolecular electron transfer and the catalytic activity of NapA. In the present study, we show that the mutation of K79 to Ala leads to an almost complete loss of activity, suggesting its role in catalytic activity. The inhibition of C. jejuni NapA by cyanide, thiocyanate, and azide has also been investigated. The inhibition studies indicate that cyanide inhibits NapA in a non-competitive manner, while thiocyanate and azide inhibit NapA in an uncompetitive manner. Neither inhibition mechanism involves direct binding of the inhibitor to the Mo-center. These results have been discussed in the context of the loss of catalytic activity of NapA K79A variant and a possible anion binding site in NapA has been proposed.
{"title":"The critical role of a conserved lysine residue in periplasmic nitrate reductase catalyzed reactions.","authors":"Nitai C Giri, Breeanna Mintmier, Manohar Radhakrishnan, Jonathan W Mielke, Jarett Wilcoxen, Partha Basu","doi":"10.1007/s00775-024-02057-x","DOIUrl":"10.1007/s00775-024-02057-x","url":null,"abstract":"<p><p>Periplasmic nitrate reductase NapA from Campylobacter jejuni (C. jejuni) contains a molybdenum cofactor (Moco) and a 4Fe-4S cluster and catalyzes the reduction of nitrate to nitrite. The reducing equivalent required for the catalysis is transferred from NapC → NapB → NapA. The electron transfer from NapB to NapA occurs through the 4Fe-4S cluster in NapA. C. jejuni NapA has a conserved lysine (K79) between the Mo-cofactor and the 4Fe-4S cluster. K79 forms H-bonding interactions with the 4Fe-4S cluster and connects the latter with the Moco via an H-bonding network. Thus, it is conceivable that K79 could play an important role in the intramolecular electron transfer and the catalytic activity of NapA. In the present study, we show that the mutation of K79 to Ala leads to an almost complete loss of activity, suggesting its role in catalytic activity. The inhibition of C. jejuni NapA by cyanide, thiocyanate, and azide has also been investigated. The inhibition studies indicate that cyanide inhibits NapA in a non-competitive manner, while thiocyanate and azide inhibit NapA in an uncompetitive manner. Neither inhibition mechanism involves direct binding of the inhibitor to the Mo-center. These results have been discussed in the context of the loss of catalytic activity of NapA K79A variant and a possible anion binding site in NapA has been proposed.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":3.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141086337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-05-29DOI: 10.1007/s00775-024-02061-1
Carlos Z Gómez-Castro, Liliana Quintanar, Alberto Vela
The influence of metal ions on the structure of amyloid- (Aβ) protofibril models was studied through molecular dynamics to explore the molecular mechanisms underlying metal-induced Aβ aggregation relevant in Alzheimer's disease (AD). The models included 36-, 48-, and 188-mers of the Aβ42 sequence and two disease-modifying variants. Primary structural effects were observed at the N-terminal domain, as it became susceptible to the presence of cations. Specially when β-sheets predominate, this motif orients N-terminal acidic residues toward one single face of the β-sheet, resulting in the formation of an acidic region that attracts cations from the media and promotes the folding of the N-terminal region, with implications in amyloid aggregation. The molecular phenotype of the protofibril models based on Aβ variants shows that the AD-causative D7N mutation promotes the formation of N-terminal β-sheets and accumulates more Zn2+, in contrast to the non-amyloidogenic rodent sequence that hinders the β-sheets and is more selective for Na+ over Zn2+ cations. It is proposed that forming an acidic β-sheet domain and accumulating cations is a plausible molecular mechanism connecting the elevated affinity and concentration of metals in Aβ fibrils to their high content of β-sheet structure at the N-terminal sequence.
通过分子动力学研究了金属离子对淀粉样蛋白-β(Aβ)原纤维模型结构的影响,以探索与阿尔茨海默病(AD)相关的金属诱导 Aβ 聚集的分子机制。这些模型包括 36、48 和 188-mers 的 Aβ42 序列以及两种可改变疾病的变体。在 N 端结构域观察到了主要的结构影响,因为它变得容易受到阳离子的影响。特别是当β片状结构占主导地位时,该图案会使 N 端酸性残基朝向β片状结构的一个单面,从而形成一个酸性区域,吸引介质中的阳离子并促进 N 端区域的折叠,从而影响淀粉样蛋白的聚集。基于 Aβ 变体的原纤维模型的分子表型显示,导致淀粉样变性的 D7N 突变促进了 N 端 β 片的形成,并积累了更多的 Zn2+,而非淀粉样变性的啮齿动物序列则阻碍了 β 片的形成,并对 Na+ 而非 Zn2+阳离子更具选择性。有人提出,形成酸性β片结构域并积聚阳离子是一种合理的分子机制,它将 Aβ 纤维中金属亲和力和浓度的提高与其 N 端序列的高含量β片结构联系起来。
{"title":"An N-terminal acidic β-sheet domain is responsible for the metal-accumulation properties of amyloid-β protofibrils: a molecular dynamics study.","authors":"Carlos Z Gómez-Castro, Liliana Quintanar, Alberto Vela","doi":"10.1007/s00775-024-02061-1","DOIUrl":"10.1007/s00775-024-02061-1","url":null,"abstract":"<p><p>The influence of metal ions on the structure of amyloid- <math><mi>β</mi></math> (Aβ) protofibril models was studied through molecular dynamics to explore the molecular mechanisms underlying metal-induced Aβ aggregation relevant in Alzheimer's disease (AD). The models included 36-, 48-, and 188-mers of the Aβ<sub>42</sub> sequence and two disease-modifying variants. Primary structural effects were observed at the N-terminal domain, as it became susceptible to the presence of cations. Specially when β-sheets predominate, this motif orients N-terminal acidic residues toward one single face of the β-sheet, resulting in the formation of an acidic region that attracts cations from the media and promotes the folding of the N-terminal region, with implications in amyloid aggregation. The molecular phenotype of the protofibril models based on Aβ variants shows that the AD-causative D7N mutation promotes the formation of N-terminal β-sheets and accumulates more Zn<sup>2+</sup>, in contrast to the non-amyloidogenic rodent sequence that hinders the β-sheets and is more selective for Na<sup>+</sup> over Zn<sup>2+</sup> cations. It is proposed that forming an acidic β-sheet domain and accumulating cations is a plausible molecular mechanism connecting the elevated affinity and concentration of metals in Aβ fibrils to their high content of β-sheet structure at the N-terminal sequence.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11186886/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141174002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-01Epub Date: 2024-05-12DOI: 10.1007/s00775-024-02060-2
Mark J Hackett
Brain iron content is widely reported to increase during "ageing", across multiple species from nematodes, rodents (mice and rats) and humans. Given the redox-active properties of iron, there has been a large research focus on iron-mediated oxidative stress as a contributor to tissue damage during natural ageing, and also as a risk factor for neurodegenerative disease. Surprisingly, however, the majority of published studies have not investigated brain iron homeostasis during the biological time period of senescence, and thus knowledge of how brain homeostasis changes during this critical stage of life largely remains unknown. This commentary examines the literature published on the topic of brain iron homeostasis during ageing, providing a critique on limitations of currently used experimental designs. The commentary also aims to highlight that although much research attention has been given to iron accumulation or iron overload as a pathological feature of ageing, there is evidence to support functional iron deficiency may exist, and this should not be overlooked in studies of ageing or neurodegenerative disease.
{"title":"A commentary on studies of brain iron accumulation during ageing.","authors":"Mark J Hackett","doi":"10.1007/s00775-024-02060-2","DOIUrl":"10.1007/s00775-024-02060-2","url":null,"abstract":"<p><p>Brain iron content is widely reported to increase during \"ageing\", across multiple species from nematodes, rodents (mice and rats) and humans. Given the redox-active properties of iron, there has been a large research focus on iron-mediated oxidative stress as a contributor to tissue damage during natural ageing, and also as a risk factor for neurodegenerative disease. Surprisingly, however, the majority of published studies have not investigated brain iron homeostasis during the biological time period of senescence, and thus knowledge of how brain homeostasis changes during this critical stage of life largely remains unknown. This commentary examines the literature published on the topic of brain iron homeostasis during ageing, providing a critique on limitations of currently used experimental designs. The commentary also aims to highlight that although much research attention has been given to iron accumulation or iron overload as a pathological feature of ageing, there is evidence to support functional iron deficiency may exist, and this should not be overlooked in studies of ageing or neurodegenerative disease.</p>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11186910/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140907957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-26DOI: 10.1007/s00775-024-02053-1
Grayson Gerlich, Callie Miller, Xinhang Yang, Karla Diviesti, Brian Bennett, Judith Klein-Seetharaman, Richard C. Holz
Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile; TPN) is an environmentally persistent fungicide that sees heavy use in the USA and is highly toxic to aquatic species and birds, as well as a probable human carcinogen. The chlorothalonil dehalogenase from Pseudomonas sp. CTN-3 (Chd, UniProtKB C9EBR5) degrades TPN to its less toxic 4-OH-TPN analog making it an exciting candidate for the development of a bioremediation process for TPN; however, little is currently known about its catalytic mechanism. Therefore, an active site residue histidine-114 (His114) which forms a hydrogen bond with the Zn(II)-bound water/hydroxide and has been suggested to be the active site acid/base, was substituted by an Ala residue. Surprisingly, ChdH114A exhibited catalytic activity with a kcat value of 1.07 s−1, ~ 5% of wild-type (WT) Chd, and a KM of 32 µM. Thus, His114 is catalytically important but not essential. The electronic and structural aspects of the WT Chd and ChdH114A active sites were examined using UV–Vis and EPR spectroscopy on the catalytically competent Co(II)-substituted enzyme as well as all-atomistic molecular dynamics (MD) simulations. Combination of these data suggest His114 can quickly and reversibly move nearly 2 Å between one conformation that facilitates catalysis and another that enables product egress and active site recharge. In light of experimental and computational data on ChdH114A, Asn216 appears to play a role in substrate binding and preorganization of the transition-state while Asp116 likely facilitates the deprotonation of the Zn(II)-bound water in the absence of His114. Based on these data, an updated proposed catalytic mechanism for Chd is presented.
{"title":"Catalytic role of histidine-114 in the hydrolytic dehalogenation of chlorothalonil by Pseudomonas sp. CTN-3","authors":"Grayson Gerlich, Callie Miller, Xinhang Yang, Karla Diviesti, Brian Bennett, Judith Klein-Seetharaman, Richard C. Holz","doi":"10.1007/s00775-024-02053-1","DOIUrl":"https://doi.org/10.1007/s00775-024-02053-1","url":null,"abstract":"<p>Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile; TPN) is an environmentally persistent fungicide that sees heavy use in the USA and is highly toxic to aquatic species and birds, as well as a probable human carcinogen. The chlorothalonil dehalogenase from <i>Pseudomonas</i> sp. CTN-3 (Chd, UniProtKB C9EBR5) degrades TPN to its less toxic 4-OH-TPN analog making it an exciting candidate for the development of a bioremediation process for TPN; however, little is currently known about its catalytic mechanism. Therefore, an active site residue histidine-114 (His114) which forms a hydrogen bond with the Zn(II)-bound water/hydroxide and has been suggested to be the active site acid/base, was substituted by an Ala residue. Surprisingly, Chd<sup>H114A</sup> exhibited catalytic activity with a <i>k</i><sub><i>cat</i></sub> value of 1.07 s<sup>−1</sup>, ~ 5% of wild-type (WT) Chd, and a <i>K</i><sub><i>M</i></sub> of 32 µM. Thus, His114 is catalytically important but not essential. The electronic and structural aspects of the WT Chd and Chd<sup>H114A</sup> active sites were examined using UV–Vis and EPR spectroscopy on the catalytically competent Co(II)-substituted enzyme as well as all-atomistic molecular dynamics (MD) simulations. Combination of these data suggest His114 can quickly and reversibly move nearly 2 Å between one conformation that facilitates catalysis and another that enables product egress and active site recharge. In light of experimental and computational data on Chd<sup>H114A</sup>, Asn216 appears to play a role in substrate binding and preorganization of the transition-state while Asp116 likely facilitates the deprotonation of the Zn(II)-bound water in the absence of His114. Based on these data, an updated proposed catalytic mechanism for Chd is presented.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":603,"journal":{"name":"JBIC Journal of Biological Inorganic Chemistry","volume":null,"pages":null},"PeriodicalIF":3.358,"publicationDate":"2024-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141152117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-12DOI: 10.1007/s00775-024-02049-x
Garima Mann, Shivani Daksh, Nikhil Kumar, Ankur Kaul, B. G. Roy, M. Thirumal, Anupama Datta
Aβ42 plaque formation is one of the preliminary pathologic events that occur post traumatic brain injury (TBI) which is also among the most noteworthy hallmarks of AD. Their pre symptomatic detection is therefore vital for better disease management. Chalcone–picolinic acid chelator derivative, 6‐({[(6‐carboxypyridin‐2‐yl)methyl](2‐{4‐[(2E)‐3‐[4‐(dimethyl amino)phenyl]prop‐2‐enoyl]phenoxy}ethyl)amino}methyl)pyridine‐2‐carboxylic acid, Py-chal was synthesized to selectively identify amyloid plaques formed post head trauma using SPECT imaging by stable complexation to 99mTc with > 97% efficiency without compromising amyloid specificity. The binding potential of the Py-chal ligand to amyloid plaques remained high as confirmed by in vitro binding assay and photophysical spectra. Further, the Py-chal complex stained amyloid aggregates in the brain sections of rmTBI mice model. In vivo scintigraphy in TBI mice model displayed high uptake followed by high retention while the healthy rabbits displayed higher brain uptake followed by a rapid washout attributed to absence of amyloid plaques. Higher uptake in brain of TBI model was also confirmed by ex vivo biodistribution analysis wherein brain uptake of 3.38 ± 0.2% ID/g at 2 min p.i. was observed for TBI mice model. This was followed by prolonged retention and more than twofold higher activity as compared to sham mice brain. This preliminary data suggests the specificity of the radiotracer for amyloid detection post head trauma and applicability of 99mTc labeled Py-chal complex for TBI-induced β-amyloid SPECT imaging.