Biochimica et Biophysica Acta-Bioenergetics最新文献_第7页

Requirement of Bacillus subtilis succinate:menaquinone oxidoreductase activity for membrane energization depends on the direction of catalysis 枯草芽孢杆菌琥珀酸：甲萘醌氧化还原酶活性对膜能量的要求取决于催化作用的方向。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-11-08 DOI: 10.1016/j.bbabio.2024.149522

Natalia V. Azarkina

Succinate:quinone oxidoreductases (SQR) from Bacilli catalyze reduction of menaquinone by succinate, as well as the reverse reaction. The direct activity is energetically unfavorable and lost upon ΔμН⁺ dissipation, thus suggesting ΔμН⁺ to be consumed during catalysis. Paradoxically, the generation of ΔμН⁺ upon fumarate reduction was never confirmed. Thus, the exact role of ΔμН⁺ in the operation of bacillary-type SQRs remained questionable. The purpose of this work was to clarify this issue.

We have described the different operating modes of the membrane-bound SQR from Bacillus subtilis. Tightly coupled membrane vesicles from both wild-type cells and the mutant containing cytochrome bd as the only terminal oxidase were studied. This made it possible to compare the respiratory chains with 2 versus 1H⁺/e⁻ stoichiometry of ΔμН⁺ generation. Direct and reverse activities of SQR were determined under either energized or deenergized conditions.

The wild-type membranes demonstrated high succinate oxidase activity very sensitive to uncoupling. On the contrary, the mutant showed extremely low succinate oxidase activity resistant to uncoupling. ΔμН⁺ generation at the cost of ATP hydrolysis restored the uncoupling sensitive succinate respiration in the mutant. Membranes of the both types effectively reduced fumarate by menaquinol. This activity was not affected by energization or uncoupling, neither it was followed by ΔμН⁺ generation.

Thus, B. subtilis SQR demonstrates two regimes: ΔμН⁺-coupled and not coupled. This behavior can be explained by assuming the presence of two menaquinone binding sites which drastically differ in affinity for the oxidized and reduced substrate.

芽孢杆菌中的琥珀酸：醌氧化还原酶（SQR）可催化琥珀酸还原甲萘醌以及反向反应。直接活性在能量上是不利的，并且在ΔμН+耗散时会丧失，因此表明ΔμН+在催化过程中会被消耗掉。矛盾的是，富马酸还原时产生的 ΔμН+ 从未得到证实。因此，ΔμН+ 在芽胞型 SQR 运行中的确切作用仍然存在疑问。这项工作的目的就是要澄清这个问题。我们描述了枯草芽孢杆菌膜结合型 SQR 的不同运行模式。我们研究了野生型细胞和含有细胞色素 bd 作为唯一末端氧化酶的突变体的紧密耦合膜囊泡。这样就可以比较呼吸链在ΔμН+生成过程中 2 和 1H+/e- 的化学计量。在通电或断电条件下测定了 SQR 的直接和反向活性。野生型膜显示出很高的琥珀酸氧化酶活性，对解偶联非常敏感。相反，突变体表现出极低的琥珀酸氧化酶活性，对解偶联具有抵抗力。以 ATP 水解为代价产生的 ΔμН+ 恢复了突变体对解偶联敏感的琥珀酸呼吸。两种类型的细胞膜都能通过甲萘醌有效地减少富马酸。这种活性不受能量化或解偶联的影响，也不会产生ΔμН+。因此，枯草芽孢杆菌 SQR 表现出两种状态：ΔμН+ 耦合和非耦合。这种行为可以通过假设存在两个对氧化底物和还原底物的亲和力截然不同的甲萘醌结合位点来解释。

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引用次数: 0

How lipid transfer proteins and the mitochondrial membrane shape the kinetics of β-oxidation the liver 脂质转移蛋白和线粒体膜如何影响肝脏β氧化的动力学。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-10-19 DOI: 10.1016/j.bbabio.2024.149519

Christoff Odendaal, Dirk-Jan Reijngoud, Barbara M. Bakker

The mitochondrial fatty acid β-oxidation (mFAO) is important for producing ATP under conditions of energetic stress, such as fasting and cold exposure. The regulation of this pathway is dependent on the kinetic properties of the enzymes involved. To better understand pathway behaviour, accurate enzyme kinetics is required. Setting up and interpreting such proper assays requires a good understanding of what influences the enzymes' kinetics. Often, knowing the buffer composition, pH, and temperature is considered to be sufficient.

Many mFAO enzymes are membrane-bound, however, and their kinetic properties depend on the composition and curvature of the mitochondrial membranes. These properties are, in turn, affected by metabolite concentrations, but are rarely accounted for in kinetic assays. Especially for carnitine palmitoyltransferase 1 (CPT1), this has been shown to be of great consequence.

Moreover, the enzymes of the mFAO metabolise water-insoluble acyl-CoA derivatives, which become toxic at high concentrations. In vivo, these are carried across the cytosol by intracellular lipid transfer proteins (iLTPs), such as the fatty-acid and acyl-CoA-binding proteins (FABP and ACBP, respectively). In vitro, this is often mimicked by using bovine serum albumin (BSA), which differs from the iLPTs in terms of its binding behaviour and subcellular localisation patterns.

In this review, we argue that the iLTPs and membrane properties cannot be ignored when measuring or interpreting the kinetics of mFAO enzymes. They should be considered fundamental to the activity of mFAO enzymes just as pH, buffer composition, and temperature are.

线粒体脂肪酸β-氧化（mFAO）对于在能量胁迫条件下（如禁食和寒冷暴露）产生 ATP 非常重要。这一途径的调节取决于相关酶的动力学特性。为了更好地了解该途径的行为，需要精确的酶动力学。要建立和解释这种正确的检测方法，就必须充分了解影响酶动力学的因素。通常认为，了解缓冲液成分、pH 值和温度就足够了。然而，许多 mFAO 酶是膜结合的，它们的动力学特性取决于线粒体膜的成分和曲率。这些特性反过来又受代谢物浓度的影响，但在动力学测定中却很少考虑到这一点。对于肉碱棕榈酰基转移酶 1（CPT1）来说，这一点尤其重要。此外，mFAO 的酶会代谢出不溶于水的酰基-CoA 衍生物，这些衍生物在高浓度时会产生毒性。在体内，这些衍生物由细胞内脂质转移蛋白（iLTPs），如脂肪酸和酰基-CoA 结合蛋白（分别为 FABP 和 ACBP）带过细胞膜。在体外，这通常是通过使用牛血清白蛋白（BSA）来模拟的，BSA 在其结合行为和亚细胞定位模式方面与 iLPTs 不同。在本综述中，我们认为在测量或解释 mFAO 酶的动力学时，不能忽视 iLTPs 和膜特性。它们应被视为 mFAO 酶活性的基础，就像 pH 值、缓冲成分和温度一样。

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引用次数: 0

In vitro photocurrents from spinach thylakoids following Mn depletion and Mn-cluster reconstitution 锰耗尽和锰簇重组后菠菜叶绿体的体外光电流。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-11-07 DOI: 10.1016/j.bbabio.2024.149523

Roman Voloshin , Maria Goncharova , Sergey K. Zharmukhamedov , Barry D. Bruce , Suleyman I. Allakhverdiev

Biohybrid devices that generate an electrical signal under the influence of light due to photochemical reactions in photosynthetic pigment-protein complexes have many prospects. On the one hand, the oxygen-evolving complex of photosystem II allows the use of ubiquitous water as a source of electrons for photoinduced electron transfer in such devices; on the other hand, it is the most vulnerable part of the photosynthetic apparatus. From the perspective of sustainable operation of bio-based hybrid devices, it is helpful to analyze how removing or modifying the Mn cluster will affect the performance of the bio-hybrid device. This work analyzed photocurrent generation in a liquid three-electrode solar cell based on manganese-depleted and reactivated thylakoid membranes. Membranes lacking Mn could not produce any significant photocurrent until manganese chloride was added. After adding MnCl₂, the cell could produce current when exposed to light. This current was about a few percent from cells with intact thylakoid membranes. However, the photoactivation procedure made it possible to restore up to 75 % of the photocurrent of cells based on intact thylakoid membranes. The main objective of this work is to answer the question about the possibility of photocurrent generation in a biohybrid system based on thylakoid membranes using artificial analogs of the native oxygen-evolving complex. Photoactivation with manganese chloride is the simplest way to obtain preparations devoid of the native Mn cluster, but capable of oxidizing water.

在光的作用下，光合色素-蛋白质复合物发生光化学反应，从而产生电信号的生物杂交装置前景广阔。一方面，光系统 II 的氧发生复合物允许在此类装置中使用无处不在的水作为光诱导电子转移的电子源；另一方面，它又是光合作用装置中最脆弱的部分。从生物基混合器件可持续运行的角度来看，分析去除或修改锰簇会如何影响生物混合器件的性能很有帮助。这项研究分析了基于锰贫化和重新激活的类硫基膜的液态三电极太阳能电池中产生的光电流。在加入氯化锰之前，缺锰膜不能产生任何明显的光电流。加入氯化锰后，细胞在光照下可以产生电流。这种电流大约是具有完整类木体膜的细胞的百分之几。然而，光激活程序使基于完整类木体膜的细胞恢复了高达 75% 的光电流。这项工作的主要目的是回答这样一个问题，即在以类囊体膜为基础的生物杂交系统中，利用原生氧发生复合物的人工类似物产生光电流的可能性。用氯化锰进行光活化是获得不含原生锰簇但能氧化水的制备物的最简单方法。

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引用次数: 0

ROS production by cytochrome bc1: Its mechanism as inferred from the effects of heme b cofactor mutants 细胞色素 bc1 产生 ROS：从血红素 b 辅因子突变体的影响推断其机制。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-09-24 DOI: 10.1016/j.bbabio.2024.149513

Jakub Pagacz , Arkadiusz Borek , Artur Osyczka

Cytochrome bc₁ is one of the enzymes of electron transport chain responsible for generation of reactive oxygen species (ROS). While ROS are considered to be products of side reactions of quinol oxidation site (Q_o), molecular aspects of their generation remain unclear. One of them concerns significance of hemes b (b_L and b_H) redox potentials (E_m) and properties on ROS generation by Q_o. Here we addressed this question by examining ROS production in mutants of bacterial cytochrome bc₁ that replaced one of the His ligand of either heme b_L or b_H with Lys or Asn. We observed that severe slowing down of electron flow by the Asn mutants induces similar effects on ROS production as inhibition by antimycin in the native cytochrome bc₁ (WT). An increase in the E_m of hemes b (either b_L or b_H) in Lys mutants does not exert major effect on the ROS production level, compared to WT. The experimental data were analyzed in the frame of a dynamic model to conclude that the observed ROS rates and levels reflect a combinatory effect of two factors: probability of heme b_L being in the reduced state and probability of electron transfer from heme b_L towards Q_o. A significant contribution from short-circuits maintains the ROS levels at ~15 % in all tested forms. Overall, ROS production by cytochrome bc₁ shows remarkably low susceptibility to changes in the E_m of heme b cofactors, leaving significance of tuning the E_m of hemes b as factor limiting superoxide production an open question.

细胞色素 bc1 是电子传递链中负责产生活性氧（ROS）的酶之一。虽然 ROS 被认为是醌氧化位点（Qo）副反应的产物，但其产生的分子方面仍不清楚。其中一个问题涉及hemes b（bL 和 bH）的氧化还原电位（Em）和特性对 Qo 产生 ROS 的影响。为了解决这个问题，我们研究了细菌细胞色素 bc1 突变体中 ROS 的产生情况，这些突变体用 Lys 或 Asn 取代了血红素 bL 或 bH 的一个 His 配体。我们观察到，Asn突变体电子流的严重减慢对ROS产生的影响与抗霉素对原生细胞色素bc1（WT）的抑制作用相似。与 WT 相比，Lys 突变体中血红蛋白 b（bL 或 bH）含量的增加并不会对 ROS 生成水平产生重大影响。在动态模型的框架下对实验数据进行分析后得出的结论是，观察到的 ROS 生成速率和水平反映了两个因素的综合影响：血红素 bL 处于还原状态的概率和电子从血红素 bL 向 Qo 转移的概率。在所有测试形式中，短路产生的大量 ROS 使 ROS 水平保持在 15%左右。总的来说，细胞色素 bc1 产生的 ROS 对血红素 b 辅因子 Em 变化的敏感性非常低，因此调整血红素 b 的 Em 作为限制超氧化物产生的因素的意义仍是一个未决问题。

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引用次数: 0

GTP before ATP: The energy currency at the origin of genes GTP先于ATP：基因起源的能量货币

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-09-24 DOI: 10.1016/j.bbabio.2024.149514

Natalia Mrnjavac, William F. Martin

Life is an exergonic chemical reaction. Many individual reactions in metabolism entail slightly endergonic steps that are coupled to free energy release, typically as ATP hydrolysis, in order to go forward. ATP is almost always supplied by the rotor-stator ATP synthase, which harnesses chemiosmotic ion gradients. Because the ATP synthase is a protein, it arose after the ribosome did. What was the energy currency of metabolism before the origin of the ATP synthase and how (and why) did ATP come to be the universal energy currency? About 27 % of a cell's energy budget is consumed as GTP during translation. The universality of GTP-dependence in ribosome function indicates that GTP was the ancestral energy currency of protein synthesis. The use of GTP in translation and ATP in small molecule synthesis are conserved across all lineages, representing energetic compartments that arose in the last universal common ancestor, LUCA. And what came before GTP? Recent findings indicate that the energy supporting the origin of LUCA's metabolism stemmed from H₂-dependent CO₂ reduction along routes that strongly resemble the reactions and transition metal catalysts of the acetyl-CoA pathway.

生命是一种外能化学反应。新陈代谢中的许多单个反应都需要稍有内能的步骤，这些步骤与自由能释放（通常是 ATP 水解）相结合，才能继续进行。ATP 几乎总是由转子-定子 ATP 合成酶提供，它利用化学渗透离子梯度。由于 ATP 合成酶是一种蛋白质，因此它出现在核糖体之后。在ATP合成酶出现之前，新陈代谢的能量货币是什么？细胞大约 27% 的能量预算在翻译过程中以 GTP 的形式消耗。核糖体功能对 GTP 的普遍依赖性表明，GTP 是蛋白质合成的祖先能量货币。GTP在翻译中的使用和ATP在小分子合成中的使用在所有细胞系中都是保留的，代表了在最后一个普遍共同祖先LUCA中出现的能量区。那么在 GTP 之前是什么呢？最新研究结果表明，支持 LUCA 新陈代谢起源的能量来自依赖 H2 的 CO2 还原，其路径与乙酰-CoA 途径的反应和过渡金属催化剂极为相似。

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引用次数: 0

Comparative thermo- and piezostability study of photosynthetic core complexes containing bacteriochlorophyll a or b 含细菌叶绿素 a 或 b 的光合作用核心复合物的热稳定性和压稳稳定性比较研究

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-11-16 DOI: 10.1016/j.bbabio.2024.149527

Margus Rätsep , Liina Kangur , Kristjan Leiger , Zheng-Yu Wang-Otomo , Arvi Freiberg

The resilience of biological systems to fluctuating environmental conditions is a crucial evolutionary advantage. In this study, we examine the thermo- and piezo-stability of the LH1-RC pigment-protein complex, the simplest photosynthetic unit, in three species of phototropic purple bacteria, each containing only this core complex. Among these species, Blastochloris viridis and Blastochloris tepida utilize bacteriochlorophyll b as the main light-harvesting pigment, while Rhodospirillum rubrum relies on bacteriochlorophyll a. Through spectroscopic analyses, we observed limited reversibility in the effects of temperature and pressure, likely due to the malleability of pigment binding sites within the light-harvesting LH1 complex. In terms of thermal robustness, LH1 complexes in a detergent environment progressively dissociate into dimeric (B820) and monomeric (B777) subunits. However, in the native membrane, degradation primarily occurs directly into B777 without the intermediate formation of B820. Interestingly, while high-pressure compression of core complexes from Blastochloris viridis and Blastochloris tepida caused significant changes in compressibility around 1.3 kbar and the formation of B777 and B820 subunits upon decompression, no such compressibility changes or pressure-induced dissociation were observed in Rhodospirillum rubrum complexes, even at pressures as high as 11 kbar. This study reveals significant differences in the piezo- and thermal properties of phototrophs containing either BChl a or BChl b, underscoring the critical role of structural factors in understanding the temperature- and pressure-induced denaturation phenomena in photosynthetic complexes. Rhodospirillum rubrum, in particular, stands out as one of the most thermodynamically stable systems among phototrophic microorganisms, capable of withstanding temperatures up to 70 °C and pressures exceeding 11 kbar.

生物系统对波动环境条件的适应能力是一项至关重要的进化优势。在这项研究中，我们考察了三种向光性紫色细菌中最简单的光合作用单元--LH1-RC色素-蛋白质复合物的热稳定性和压稳定性，每种细菌都只含有这一核心复合物。通过光谱分析，我们观察到温度和压力的影响具有有限的可逆性，这可能是由于采光 LH1 复合物中的色素结合位点具有延展性。就热稳定性而言，LH1 复合物在洗涤剂环境中会逐渐解离为二聚体（B820）和单体（B777）亚基。然而，在原生膜中，降解主要直接发生在 B777 中，而没有中间形成 B820。有趣的是，当高压压缩 Blastochloris viridis 和 Blastochloris tepida 的核心复合物时，在 1.3 千巴左右会导致可压缩性发生显著变化，并在减压时形成 B777 和 B820 亚基，而在 Rhodospirillum rubrum 复合物中，即使在高达 11 千巴的压力下，也没有观察到这种可压缩性变化或压力引起的解离。这项研究揭示了含有 BChl a 或 BChl b 的光营养体在压变和热变特性上的显著差异，强调了结构因素在理解光合复合体中温度和压力诱导的变性现象中的关键作用。特别是红柱孢霉（Rhodospirillum rubrum），它是光营养微生物中热力学最稳定的系统之一，能够承受高达 70 ℃ 的温度和超过 11 千巴的压力。

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引用次数: 0

The molecular structure of an axle-less F1-ATPase 无轴 F1-ATP 酶的分子结构。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-10-18 DOI: 10.1016/j.bbabio.2024.149521

Emily J. Furlong , Ian-Blaine P. Reininger-Chatzigiannakis , Yi C. Zeng , Simon H.J. Brown , Meghna Sobti , Alastair G. Stewart

F₁F_o ATP synthase is a molecular rotary motor that can generate ATP using a transmembrane proton motive force. Isolated F₁-ATPase catalytic cores can hydrolyse ATP, passing through a series of conformational states involving rotation of the central γ rotor subunit and the opening and closing of the catalytic β subunits. Cooperativity in F₁-ATPase has long thought to be conferred through the γ subunit, with three key interaction sites between the γ and β subunits being identified. Single molecule studies have demonstrated that the F₁ complexes lacking the γ axle still “rotate” and hydrolyse ATP, but with less efficiency. We solved the cryogenic electron microscopy structure of an axle-less Bacillus sp. PS3 F₁-ATPase. The unexpected binding-dwell conformation of the structure in combination with the observed lack of interactions between the axle-less γ and the open β subunit suggests that the complete γ subunit is important for coordinating efficient ATP binding of F₁-ATPase.

F1Fo ATP 合酶是一种分子旋转马达，可利用跨膜质子动力产生 ATP。分离的 F1-ATP 酶催化核心可以水解 ATP，并通过一系列构象状态，包括中心 γ 转子亚基的旋转和催化 β 亚基的开合。长期以来，人们一直认为 F1-ATP 酶的协同作用是通过 γ 亚基实现的，并已发现 γ 和 β 亚基之间有三个关键的相互作用位点。单分子研究表明，缺少γ轴的F1复合物仍能 "旋转 "并水解ATP，但效率较低。我们解决了无轴芽孢杆菌 PS3 F1-ATP 酶的低温电子显微镜结构。该结构意想不到的结合-停留构象，以及观察到的无轴γ和开放β亚基之间缺乏相互作用的现象表明，完整的γ亚基对于协调F1-ATP酶有效的ATP结合非常重要。

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引用次数: 0

Anaesthetics disrupt complex I-linked respiration and reverse the ATP synthase 麻醉剂会破坏与复合体 I 相连的呼吸作用，并逆转 ATP 合酶。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-09-24 DOI: 10.1016/j.bbabio.2024.149511

Enrique Rodriguez , Bella Peng , Nick Lane

The mechanism of volatile general anaesthetics has long been a mystery. Anaesthetics have no structural motifs in common, beyond lipid solubility, yet all exert a similar effect. The fact that the inert gas xenon is an anaesthetic suggests their common mechanism might relate to physical rather than chemical properties. Electron transfer through chiral proteins can induce spin polarization. Recent work suggests that anaesthetics dissipate spin polarization during electron transfer to oxygen, slowing respiration. Here we show that the volatile anaesthetics isoflurane and sevoflurane specifically disrupt complex I-linked respiration in the thoraces of Drosophila melanogaster, with less effect on maximal respiration. Suppression of complex I-linked respiration was greatest with isoflurane. Using high-resolution tissue fluorespirometry, we show that these anaesthetics simultaneously increase mitochondrial membrane potential, implying reversal of the ATP synthase. Inhibition of ATP synthase with oligomycin prevented respiration and increased membrane potential back to the maximal (LEAK state) potential. Magnesium-green fluorescence predicted a collapse in ATP availability following a single anaesthetic dose, consistent with ATP hydrolysis through reversal of the ATP synthase. Raised membrane potential corresponded to a rise in ROS flux, especially with isoflurane. Anaesthetic doses causing respiratory suppression were in the same range as those that induce anaesthesia, although we could not establish tissue concentrations. Our findings show that anaesthetics suppress complex I-linked respiration with concerted downstream effects. But we cannot explain why only mutations in complex I, and not elsewhere in the electron-transfer system, confer hypersensitivity to anaesthetics.

长期以来，挥发性全身麻醉剂的作用机制一直是个谜。除了脂溶性之外，麻醉剂在结构上没有共同之处，但却都能产生类似的效果。惰性气体氙也是一种麻醉剂，这一事实表明它们的共同机制可能与物理特性而非化学特性有关。通过手性蛋白质的电子传递可引起自旋极化。最近的研究表明，麻醉剂会在电子传递到氧气的过程中消散自旋极化，从而减慢呼吸速度。在这里，我们发现挥发性麻醉剂异氟醚和七氟醚会特异性地破坏黑腹果蝇胸廓中与 I 链接的复合呼吸，但对最大呼吸的影响较小。异氟醚对复合物 I 链接呼吸的抑制作用最大。利用高分辨率组织荧光呼吸测定法，我们发现这些麻醉剂同时会增加线粒体膜电位，这意味着 ATP 合成酶发生了逆转。用寡霉素抑制 ATP 合成酶可阻止呼吸作用，并使膜电位恢复到最大（LEAK 状态）电位。镁绿荧光预示着单剂量麻醉后 ATP 的可用性会崩溃，这与通过逆转 ATP 合成酶进行 ATP 水解是一致的。膜电位的升高与 ROS 通量的升高相对应，尤其是异氟醚。导致呼吸抑制的麻醉剂剂量与诱导麻醉的剂量范围相同，但我们无法确定组织浓度。我们的研究结果表明，麻醉剂会抑制复合物 I 链接呼吸，并产生协同下游效应。但我们无法解释为什么只有复合体 I 的突变，而不是电子传递系统的其他部位的突变，才会导致对麻醉剂的过敏。

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引用次数: 0

Insights into electron transfer and bifurcation of the Synechocystis sp. PCC6803 hydrogenase reductase module 洞察 Synechocystis sp. PCC6803 氢酶还原酶模块的电子传递和分叉。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-09-06 DOI: 10.1016/j.bbabio.2024.149508

Elisabeth Lettau , Christian Lorent , Jens Appel , Marko Boehm , Paul R.F. Cordero , Lars Lauterbach

The NAD⁺-reducing soluble [NiFe] hydrogenase (SH) is the key enzyme for production and consumption of molecular hydrogen (H₂) in Synechocystis sp. PCC6803. In this study, we focused on the reductase module of the SynSH and investigated the structural and functional aspects of its subunits, particularly the so far elusive role of HoxE. We demonstrated the importance of HoxE for enzyme functionality, suggesting a regulatory role in maintaining enzyme activity and electron supply. Spectroscopic analysis confirmed that HoxE and HoxF each contain one [2Fe2S] cluster with an almost identical electronic structure. Structure predictions, alongside experimental evidence for ferredoxin interactions, revealed a remarkable similarity between SynSH and bifurcating hydrogenases, suggesting a related functional mechanism. Our study unveiled the subunit arrangement and cofactor composition essential for biological electron transfer. These findings enhance our understanding of NAD⁺-reducing [NiFe] hydrogenases in terms of their physiological function and structural requirements for biotechnologically relevant modifications.

NAD+还原型可溶性[NiFe]氢酶（SH）是Synechocystis sp. PCC6803产生和消耗分子氢（H2）的关键酶。在本研究中，我们重点研究了 SynSH 的还原酶模块，并调查了其亚基的结构和功能方面，尤其是迄今为止难以捉摸的 HoxE 的作用。我们证明了 HoxE 对酶功能的重要性，表明它在维持酶活性和电子供应方面起着调节作用。光谱分析证实，HoxE 和 HoxF 各含有一个[2Fe2S]簇，其电子结构几乎完全相同。结构预测以及铁氧还蛋白相互作用的实验证据揭示了 SynSH 与分叉氢化酶之间的显著相似性，这表明两者之间存在相关的功能机制。我们的研究揭示了生物电子传递所必需的亚基排列和辅助因子组成。这些发现加深了我们对 NAD+ 还原型[NiFe]氢化酶生理功能和生物技术相关修饰结构要求的了解。

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引用次数: 0

D1-Tyr246 and D2-Tyr244 in photosystem II: Insights into bicarbonate binding and electron transfer from QA•− to QB 光系统 II 中的 D1-Tyr246 和 D2-Tyr244：对碳酸氢盐结合以及从 QA 到 QB 的电子传递的见解。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2025-01-01 Epub Date: 2024-08-30 DOI: 10.1016/j.bbabio.2024.149507

Ruri Nihara , Keisuke Saito , Hiroshi Kuroda , Yasuto Komatsu , Yang Chen , Hiroshi Ishikita , Yuichiro Takahashi

In photosystem II (PSII), D1-Tyr246 and D2-Tyr244 are symmetrically located at the binding site of the bicarbonate ligand of the non-heme Fe complex. Here, we investigated the role of the symmetrically arranged tyrosine pair, D1-Tyr246 and D2-Tyr244, in the function of PSII, by generating four chloroplast mutants of PSII from Chlamydomonas reinhardtii: D1-Y246F, D1-Y246T, D2-Y244F, and D2-Y244T. The mutants exhibited altered photoautotrophic growth, reduced PSII protein accumulation, and impaired O₂-evolving activity. Flash-induced fluorescence yield decay kinetics indicated a significant slowdown in electron transfer from Q_A^•− to Q_B in all mutants. Bicarbonate reconstitution resulted in enhanced O₂-evolving activity, suggesting destabilization of bicarbonate binding in the mutants. Structural analyses based on a quantum mechanical/molecular mechanical approach identified the existence of a water channel that leads to incorporation of bulk water molecules and destabilization of the bicarbonate binding site. The water intake channels, crucial for bicarbonate stability, exhibited distinct paths in the mutants. These findings shed light on the essential role of the tyrosine pair in maintaining bicarbonate stability and facilitating efficient electron transfer in native PSII.

在光系统 II（PSII）中，D1-Tyr246 和 D2-Tyr244 对称位于非血红素铁复合物的碳酸氢盐配体的结合部位。在这里，我们通过从莱茵衣藻（Chlamydomonas reinhardtii）中产生四种 PSII 叶绿体突变体，研究了对称排列的酪氨酸对 D1-Tyr246 和 D2-Tyr244 在 PSII 功能中的作用：D1-Y246F、D1-Y246T、D2-Y244F 和 D2-Y244T。这些突变体表现出光自养生长的改变、PSII 蛋白积累的减少以及 O2 生成活性的减弱。闪烁诱导的荧光产量衰减动力学表明，在所有突变体中，从QA--到QB的电子传递速度明显减慢。碳酸氢盐重组导致 O2 生成活性增强，这表明突变体中碳酸氢盐结合不稳定。基于量子力学/分子力学方法的结构分析确定了水通道的存在，该通道导致大量水分子的加入和碳酸氢盐结合位点的不稳定。对碳酸氢盐稳定性至关重要的进水通道在突变体中表现出不同的路径。这些发现揭示了酪氨酸对在维持碳酸氢盐稳定性和促进原生 PSII 高效电子传递方面的重要作用。

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