Biochimica et Biophysica Acta-Bioenergetics最新文献

Finding the E-channel proton loading sites by calculating the ensemble of protonation microstates 通过计算质子化微观状态的集合，找到 E 通道质子装载点。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2024-10-21 DOI: 10.1016/j.bbabio.2024.149518

Md. Raihan Uddin , Umesh Khaniya , Chitrak Gupta , Junjun Mao , Gehan A. Ranepura , Rongmei Judy Wei , Jose Ortiz-Soto , Abhishek Singharoy , M.R. Gunner

The aerobic electron transfer chain builds a proton gradient by proton coupled electron transfer reactions through a series of proteins. Complex I is the first enzyme in the sequence. Here transfer of two electrons from NADH to quinone yields four protons pumped from the membrane N- (negative, higher pH) side to the P- (positive, lower pH) side. Protons move through three linear antiporter paths, with a few amino acids and waters providing the route; and through the E-channel, a complex of competing paths, with clusters of interconnected protonatable residues.

Proton loading sites (PLS) transiently bind protons as they are transported from N- to P-compartments. PLS can be individual residues or extended clusters of residues. The program MCCE uses Monte Carlos sampling to analyze the E-channel proton binding in equilibrium with individual Molecular Dynamics snapshots from trajectories of Thermus thermuphillus Complex I in the apo, quinone and quinol bound states. At pH 7, the five E-channel subunits (Nqo4, Nqo7, Nqo8, Nqo10, and Nqo11) take >25,000 protonation microstates, each with different residues protonated. The microstate explosion is tamed by analyzing interconnected clusters of residues along the proton transfer paths. A proton is bound and released from a cluster of five coupled residues on the protein N-side and to six coupled residues in the protein center. Loaded microstates bind protons to sites closer to the P-side in the forward pumping direction. MCCE microstate analysis identifies strongly coupled proton binding amongst individual residues in the two PLS clusters.

有氧电子传递链通过一系列蛋白质的质子耦合电子传递反应建立质子梯度。复合体 I 是该序列中的第一个酶。在这里，两个电子从 NADH 转移到醌，产生四个质子，从膜的 N 侧（负极，pH 值较高）泵送到 P 侧（正极，pH 值较低）。质子通过三条线性反转运路径移动，其中几种氨基酸和水提供了移动路径；质子通过 E 通道移动，这是一条相互竞争的复杂路径，其中有几簇相互连接的可质子化残基。质子装载位点（PLS）会在质子从 N-Compartments 运输到 P-Compartments 时瞬时结合质子。质子装载位点可以是单个残基，也可以是扩展的残基簇。MCCE 程序使用蒙特卡洛采样法，分析了 E 通道质子结合的平衡状态，以及 Thermus thermuphillus Complex I 在 apo、醌和醌结合状态下的分子动力学轨迹快照。在 pH 值为 7 时，五个 E 通道亚基（Nqo4、Nqo7、Nqo8、Nqo10 和 Nqo11）的质子化微态超过 25,000 种，每种微态都有不同的残基质子化。通过分析质子传递路径上相互连接的残基簇，可以控制微态爆炸。质子从蛋白质 N 侧的五个耦合残基簇结合并释放到蛋白质中心的六个耦合残基。在前向泵送方向上，负载微态将质子结合到更靠近 P 侧的位置。MCCE 微态分析确定了两个 PLS 簇中单个残基之间的强耦合质子结合。

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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 : 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

Lysine 204 is crucial for the antiport function of the human LAT1 transporter 赖氨酸 204 对人类 LAT1 转运体的反转运功能至关重要。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2024-10-18 DOI: 10.1016/j.bbabio.2024.149520

Mariafrancesca Scalise , Raffaella Scanga , Lara Console , Michele Galluccio , Lorena Pochini , Cesare Indiveri

LAT1 (SLC7A5) catalyzes an antiport reaction of amino acids with specificity towards the essential ones. It is mainly expressed at the Blood Brain Barrier and placenta barriers, but it becomes over-expressed in virtually all human cancers even if originating from tissues with lower expression levels. The antiport reaction of LAT1 is crucial at the BBB since its inherited loss causes Autism Spectrum Disorder. We have investigated the possible molecular determinant of the antiport by site-directed mutagenesis, in vitro transport assay and computational analysis. Previous data indicated that mutation of K204 impairs, but does not knock-out LAT1 functionality. We have investigated the activity changes in the K204Q mutant by following the transport of [³H]-histidine, one of the major substrates, in proteoliposomes harbouring the WT or K204Q. In the mutant, the [³H]-histidine uptake and efflux are not more stimulated by the counter-substrate as they occur in the WT. Moreover, the mutation strongly decreases the substrate affinity and alters the pH dependence of K204Q. Molecular Dynamics analysis correlates well with the experimental data since it shows that substrate prematurely escapes the binding site. In addition, the K204Q shows a strongly increased mobility in those regions, transmembrane domains and random coils, involved in the transport cycle. The identified Lys residue could be responsible of the same phenomenon in those members of the SLC7 family, described as antiporters, in which it is conserved.

LAT1（SLC7A5）催化氨基酸的反转运反应，对必需氨基酸具有特异性。它主要在血脑屏障和胎盘屏障中表达，但在几乎所有人类癌症中都会过度表达，即使是来自表达水平较低的组织。由于 LAT1 的遗传性缺失会导致自闭症谱系障碍，因此它在血脑屏障中的反转运反应至关重要。我们通过定点突变、体外转运试验和计算分析研究了反转运的可能分子决定因素。之前的数据表明，K204 的突变会损害 LAT1 的功能，但不会导致其丧失。我们通过跟踪[3H]-组氨酸（主要底物之一）在含有 WT 或 K204Q 的蛋白脂质体中的转运情况，研究了 K204Q 突变体的活性变化。在突变体中，[3H]-组氨酸的摄取和流出并没有像在 WT 中那样受到反底物的刺激。此外，突变体强烈降低了底物亲和力，并改变了 K204Q 的 pH 依赖性。分子动力学分析与实验数据密切相关，因为它显示底物过早地脱离了结合位点。此外，K204Q 在参与运输循环的跨膜结构域和随机线圈等区域的移动性显著增加。在被称为反转运体的 SLC7 家族成员中，所发现的赖氨酸残基也可能是造成相同现象的原因，因为在这些成员中，赖氨酸残基是保守的。

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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 : 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

Metabolic impairments in neurodegeneration with brain iron accumulation 神经退行性病变中的代谢损伤与脑铁积聚。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2024-10-02 DOI: 10.1016/j.bbabio.2024.149517

Agata Wydrych , Barbara Pakuła , Justyna Janikiewicz , Aneta M. Dobosz , Patrycja Jakubek-Olszewska , Marta Skowrońska , Iwona Kurkowska-Jastrzębska , Maciej Cwyl , Mariola Popielarz , Paolo Pinton , Barbara Zavan , Agnieszka Dobrzyń , Magdalena Lebiedzińska-Arciszewska , Mariusz R. Więckowski

Neurodegeneration with brain iron accumulation (NBIA) is a broad, heterogeneous group of rare inherited diseases (1–3 patients/1,000,000 people) characterized by progressive symptoms associated with excessive abnormal iron deposition in the brain. Approximately 15,000–20,000 individuals worldwide are estimated to be affected by NBIA. NBIA is usually associated with slowly progressive pyramidal and extrapyramidal symptoms, axonal motor neuropathy, optic nerve atrophy, cognitive impairment and neuropsychiatric disorders. To date, eleven subtypes of NBIA have been described and the most common ones include pantothenate kinase-associated neurodegeneration (PKAN), PLA2G6-associated neurodegeneration (PLAN), mitochondrial membrane protein-associated neurodegeneration (MPAN) and beta-propeller protein-associated neurodegeneration (BPAN). We present a comprehensive overview of the evidence for disturbed cellular homeostasis and metabolic alterations in NBIA variants, with a careful focus on mitochondrial bioenergetics and lipid metabolism which drives a new perspective in understanding the course of this infrequent malady.

脑铁积聚性神经变性（NBIA）是一类广泛、异质性的罕见遗传性疾病（1-3 名患者/1,000,000 人），其特征是与脑内过量异常铁沉积有关的进行性症状。据估计，全球约有 15,000-20,000 人受到 NBIA 的影响。NBIA 通常伴有缓慢进展的锥体和锥体外系症状、轴索运动神经病变、视神经萎缩、认知障碍和神经精神障碍。迄今为止，已描述了 11 种 NBIA 亚型，其中最常见的包括泛酸激酶相关神经变性（PKAN）、PLA2G6 相关神经变性（PLAN）、线粒体膜蛋白相关神经变性（MPAN）和β-螺旋桨蛋白相关神经变性（BPAN）。我们全面概述了 NBIA 变体中细胞稳态紊乱和代谢改变的证据，重点关注线粒体生物能和脂质代谢，为了解这种罕见疾病的病程提供了新的视角。

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引用次数: 0

In isolated brown adipose tissue mitochondria, UCP1 is not essential for - nor involved in - the uncoupling effects of the classical uncouplers FCCP and DNP 在离体棕色脂肪组织线粒体中，UCP1 对于经典解偶联剂 FCCP 和 DNP 的解偶联效应既不是必需的，也不参与其中。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2024-09-30 DOI: 10.1016/j.bbabio.2024.149516

Irina G. Shabalina, Beatriz Jiménez, Celso Pereira Batista Sousa-Filho, Barbara Cannon, Jan Nedergaard

Recent patch-clamp studies of mitoplasts have challenged the traditional view that classical chemical uncoupling (by e.g. FCCP or DNP) is due to the protonophoric property of these substances themselves. These studies instead suggest that in brown-fat mitochondria, FCCP- and DNP-induced uncoupling is mediated through activation of UCP1 (and in other tissues by activation of the adenine nucleotide transporter). These studies thus advocate an entirely new paradigm for the interpretation of standard bioenergetic experiments.

To examine whether these patch-clamp results obtained in brown-fat mitoplasts are directly transferable to classical isolated brown-fat mitochondria studies, we investigated the effects of FCCP and DNP in brown-fat mitochondria from wildtype and UCP1 KO mice, comparing the FCCP and DNP effects with those of a fatty acid (oleate), a bona fide activator of UCP1.

Whereas the sensitivity of brown-fat mitochondria to oleate was much higher in UCP1-containing than in UCP1 KO mitochondria, there was no difference in sensitivity to FCCP and DNP between these mitochondria, neither in oxygen consumption rate nor in membrane potential studies. Correspondingly, the UCP1-dependent ability of GDP to competitively inhibit activation by oleate was not seen with FCCP and DNP.

It would thus be premature to abandon the established bioenergetic interpretation of chemical uncoupler effects in classical isolated brown-fat mitochondria—and probably also generally in this type of mitochondrial study. Understanding the molecular and structural reasons for the different outcomes of mitoplast and mitochondrial studies is a challenging task.

最近对有丝分裂体进行的膜片钳研究对传统观点提出了质疑，即传统的化学解偶联（如 FCCP 或 DNP）是由于这些物质本身的质子性。这些研究表明，在褐脂线粒体中，FCCP 和 DNP 诱导的解偶联是通过激活 UCP1 介导的（在其他组织中则是通过激活腺嘌呤核苷酸转运体介导的）。因此，这些研究为解读标准生物能实验提供了一种全新的范式。为了检验这些在褐脂有丝分裂体中获得的贴片钳结果是否可直接用于经典的离体褐脂线粒体研究，我们研究了 FCCP 和 DNP 对野生型小鼠和 UCP1 KO 小鼠褐脂线粒体的影响，并将 FCCP 和 DNP 的影响与脂肪酸（油酸）（UCP1 的真正激活剂）的影响进行了比较。虽然含有 UCP1 的褐脂线粒体对油酸的敏感性远高于 UCP1 KO 线粒体，但这些线粒体对 FCCP 和 DNP 的敏感性没有差异，无论是耗氧率还是膜电位研究都是如此。相应地，依赖于 UCP1 的 GDP 竞争性抑制油酸激活的能力在 FCCP 和 DNP 中也没有体现出来。因此，在经典的离体棕色脂肪线粒体研究中--或许在这类线粒体研究中也是如此--放弃对化学解偶联剂效应的既定生物能解释还为时过早。了解有丝分裂体和线粒体研究产生不同结果的分子和结构原因是生物能学中一项具有挑战性的任务。

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引用次数: 0

An unusual triplet population pathway in the Reaction Centre of the Chlorophyll-d binding Photosystem I of A. marina, as revealed by a combination of TR-EPR and ODMR spectroscopies 结合 TR-EPR 和 ODMR 光谱法，揭示了 A. marina 结合叶绿素-d 的光系统 I 反应中心中不寻常的三重子群途径。

IF 3.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Biochimica et Biophysica Acta-Bioenergetics

Pub Date : 2024-09-28 DOI: 10.1016/j.bbabio.2024.149515

Alessandro Agostini , Andrea Calcinoni , Anastasia A. Petrova , Marco Bortolus , Anna Paola Casazza , Donatella Carbonera , Stefano Santabarbara

Photo-induced Chlorophyll (Chl) triplet states in the isolated Photosystem I (PSI) of Acaryochloris marina, that harbours Chl d as its main pigment, were investigated by Optically Detected Magnetic Resonance (ODMR) and Time-Resolved Electron Paramagnetic Resonance (TR-EPR), and as a function of pre-illumination of the sample under reducing redox poising. Fluorescence Detected Magnetic Resonance (FDMR) allowed resolving four Chl d triplet (³Chl d) populations (T₁-T₄) both in untreated and illuminated samples in the presence of ascorbate and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD). The FDMR signals increased following the pre-illumination treatment, particularly for the T₃ and T₄ populations, which are therefore sensitive to the redox state of PSI cofactors. Microwave-induced Triplet minus Singlet (TmS) spectra were detected in the |D|-|E| resonance window of the T₃ and T₄ triplets. These showed a broad singlet bleaching centred at 740 nm and also displayed complex spectral structure with several derivative-like features, indicating that both the T₃ and T₄ ³Chl d populations are associated with the PSI reaction centre (RC) triplet,

{{}^{3}P}_{740}

. Parallel measurements by TR-EPR demonstrated that triplet signals observed under all conditions investigated are dominated by an electron spin polarisation (esp), which is typical of intersystem crossing, differently from what expected for recombination triplet states formed from a radical pair precursor. Moreover, stronger reductant conditions obtained by pre-illumination of the samples in the presence of dithionite and 5-methylphenazinium methyl sulfate (PMS) did not lead to a recombination triplet state esp, but rather to a decrease of the whole signal intensity. The energetics of A. marina PSI and the possible occurrence of distributions of cofactors redox properties are discussed in order to address the unexpected

{{}^{3}P}_{740}

esp.

通过光学检测磁共振（ODMR）和时间分辨电子顺磁共振（TR-EPR）研究了以 Chl d 为主要色素的海水藻（Acaryochloris marina）分离光系统 I（PSI）中光诱导的叶绿素（Chl）三重态，并将其作为还原氧化还原条件下样品预照明的函数。在抗坏血酸和 N,N,N',N'-四甲基对苯二胺（TMPD）存在的情况下，荧光检测磁共振（FDMR）可以分辨未经处理和经过光照的样品中的四个 Chl d 三重（3Chl d）群（T1-T4）。经过光照前处理后，FDMR 信号增加，特别是 T3 和 T4 群，因此它们对 PSI 辅助因子的氧化还原状态很敏感。在 T3 和 T4 三联体的|D|-|E|共振窗口中检测到了微波诱导的三联体减单联体（TmS）光谱。这表明 T3 和 T43Chl d 群体与 PSI 反应中心 (RC) 三重子 P3740 有关。通过 TR-EPR 进行的平行测定表明，在所有研究条件下观察到的三重态信号都以电子自旋极化（esp）为主，这是典型的系统间交叉，不同于由自由基对前体形成的重组三重态。此外，在有连二亚硫酸盐和 5-甲基吩嗪甲基硫酸盐（PMS）存在的情况下对样品进行预照亮而获得的较强还原剂条件并不会导致重组三重态 esp 的出现，反而会导致整个信号强度的下降。为了解决意外的 P3740 esp 问题，我们讨论了 A. marina PSI 的能量学和可能出现的辅助因子氧化还原特性分布。

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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 : 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 : 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

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 : 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