Biochimica et Biophysica Acta-Bioenergetics最新文献

{"title":"Dynamic binding of acetogenin-type inhibitors to mitochondrial complex I revealed by photoaffinity labeling","authors":"Misaki Nishida ,&nbsp;Cristina Pecorilla ,&nbsp;Takahiro Masuya ,&nbsp;Keitaro Hirano ,&nbsp;Masato Abe ,&nbsp;Oleksii Zdorevskyi ,&nbsp;Vivek Sharma ,&nbsp;Hideto Miyoshi ,&nbsp;Masatoshi Murai","doi":"10.1016/j.bbabio.2025.149566","DOIUrl":"10.1016/j.bbabio.2025.149566","url":null,"abstract":"<div><div>Acetogenins isolated from the <em>Annonaceae</em> plant family are potent inhibitors of mitochondrial NADH-ubiquinone (UQ) oxidoreductase (complex I). Since acetogenins have a markedly different chemical framework from other complex I inhibitors, studying their inhibitory action offers valuable insights into the mechanism of complex I inhibition. A cryo-EM structure of mouse complex I with a bound ~35 Å-long acetogenin derivative suggested that acetogenins bind along the full length of the predicted UQ-accessing tunnel, with their γ-lactone ring orientating toward the iron‑sulfur cluster N2. However, this binding mode does not fully explain the structure–activity relationships of various acetogenin derivatives. To further elucidate their inhibition mechanism, we conducted photoaffinity labeling experiments in bovine heart SMPs using a photoreactive acetogenin derivative DLA-1, containing a small photolabile diazirine near the γ-lactone ring. DLA-1 labeled both the complex I subunits 49-kDa and ND1, which define the architecture of “top” and “bottom” regions of the canonical UQ-accessing tunnel, respectively. Proteomic analysis revealed that the labeled sites in ND1 are not within the tunnel's interior, whereas in the case of 49-kDa subunit, part of the tunnel's inner region is labeled. To investigate the molecular basis of acetogenin binding, we performed atomistic molecular dynamics simulations of DLA-1 and a natural-type acetogenin analog in the UQ-accessing tunnel. The simulation data indicate that DLA-1 is relatively rigid yet adopts multiple conformations and interacts with several regions in the tunnel including the residues identified by photoaffinity labeling. Based on these results, we discuss the binding modes of acetogenin analogs to complex I.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 4","pages":"Article 149566"},"PeriodicalIF":3.4,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144545921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human VDAC3 as a sensor of the intracellular redox state: contribution to cytoprotection mechanisms in oxidative stress","authors":"Martyna Baranek-Grabińska ,&nbsp;Tomasz Skrzypczak ,&nbsp;Hanna Kmita ,&nbsp;Andonis Karachitos","doi":"10.1016/j.bbabio.2025.149565","DOIUrl":"10.1016/j.bbabio.2025.149565","url":null,"abstract":"<div><div>Voltage-dependent anion channels (VDACs) are essential for mitochondrial function, facilitating the exchange of metabolites between the cytosol and mitochondria. This study investigated the role of human VDAC paralogs, hVDAC1, hVDAC2, and hVDAC3, in maintaining mitochondrial function under oxidative stress in <em>Saccharomyces cerevisiae</em> strains lacking endogenous VDACs (encoded by <em>POR1</em> and <em>POR2</em>) and antioxidant enzymes, i.e., superoxide dismutases (encoded by <em>SOD1</em> and <em>SOD2</em>). The yeast cells expressing hVDAC3 showed stable growth under oxidative stress, maintained mitochondrial membrane potential and morphology, exhibited reduced superoxide anion levels, and achieved efficient ATP synthesis with minimal proton leak. In contrast, the cells expressing hVDAC1 or hVDAC2 presented impaired mitochondrial function which was supported by differences in bioenergetic profiles including ATP synthesis and proton leak but also FCCP uncoupling capacity and spare respiratory capacity. The cysteine-depleted variant of hVDAC3 (hVDAC3ΔCys) showed impaired cell growth under stress conditions, indicating that the cysteine residues in hVDAC3 are essential for its protective role. These findings highlight the unique protective function of hVDAC3 under oxidative stress, which is attributed to efficient metabolite transport and regulation via cysteine oxidation.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 4","pages":"Article 149565"},"PeriodicalIF":3.4,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144517673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ATP requirements for growth reveal the bioenergetic impact of mitochondrial symbiosis","authors":"William F. Martin","doi":"10.1016/j.bbabio.2025.149564","DOIUrl":"10.1016/j.bbabio.2025.149564","url":null,"abstract":"<div><div>Studies by microbiologists in the 1970s provided robust estimates for the energy supply and demand of a prokaryotic cell. The amount of ATP needed to support growth was calculated from the chemical composition of the cell and known enzymatic pathways that synthesize its constituents from known substrates in culture. Starting in 2015, geneticists and evolutionary biologists began investigating the bioenergetic role of mitochondria at eukaryote origin and energy in metazoan evolution using their own, widely trusted—but hitherto unvetted—model for the costs of growth in terms of ATP per cell. The more recent model contains, however, a severe and previously unrecognized error that systematically overestimates the ATP cost of amino acid synthesis up to 200-fold. The error applies to all organisms studied by such models and leads to conspicuously false inferences, for example that the synthesis of an average amino acid in humans requires 30 ATP, which no biochemistry textbook will confirm. Their ATP ‘cost’ calculations would require that <em>E. coli</em> obtains ~100 ATP per glucose and that mammals obtain ~240 ATP per glucose, untenable propositions that invalidate and void all evolutionary inferences so based. By contrast, established methods for estimating the ATP cost of microbial growth show that the first mitochondrial endosymbionts could have easily doubled the host's available ATP pool, provided (i) that genes for growth on environmental amino acids were transferred from the mitochondrial symbiont to the archaeal host, and (ii) that the host for mitochondrial origin was an autotroph using the acetyl-CoA pathway. Stated in simple terms, the significance of these findings are this: Life is a chemical reaction. It requires energy release in order to proceed. The currency of energy in cells is adenosine triphosphate, ATP. Five decades ago, microbiologists were able to measure and understand the amount of ATP that cells require to grow. New studies by evolutionary biologists have appeared in the meantime that brush aside the older microbiological findings, using their own methods to calculate the ATP cost of growth instead. Science is, however, an imperfect undertaking. The new studies contain a major error, similar to conflating centimeters with yards. The error affects many publications and their conclusions. Using the old methods, we can still meaningfully study the role of energy in evolution, including the origin of complex, nucleus-bearing cells.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 4","pages":"Article 149564"},"PeriodicalIF":3.4,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144499075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conformational dynamics of a histidine molecular switch in a cation/proton antiporter","authors":"Cristina Pecorilla ,&nbsp;Anton Altmeyer ,&nbsp;Outi Haapanen ,&nbsp;Yongchan Lee ,&nbsp;Volker Zickermann ,&nbsp;Vivek Sharma","doi":"10.1016/j.bbabio.2025.149563","DOIUrl":"10.1016/j.bbabio.2025.149563","url":null,"abstract":"<div><div>Multisubunit Mrp (<u>m</u>ultiple <u>r</u>esistance and <u>p</u>H adaptation) type sodium proton antiporters are indispensable for the growth of alkali and salt tolerant bacteria and archaea. They share sequence and structural similarity with the membrane domain of respiratory complex I, a key mitochondrial enzyme. The molecular mechanism of complex I and Mrp antiporters has remained largely unknown and is the subject of intense debate. Here, by combining site-directed mutagenesis with large-scale molecular dynamics simulations, we explore the conformational dynamics of a key histidine residue in the MrpA subunit of the antiporter. We show that point mutations perturbing the conformational mobility of the histidine sidechain directly affect the transport activity of the antiporter. We identify that protonation state variations in conserved lysine residues around the histidine drive hydrogen bonding rearrangements and hydration changes coupled to sidechain and backbone conformational dynamics. Finally, we develop detailed and testable mechanistic models of proton transfer in Mrp antiporter and complex I, in which the histidine switch functions as a unique gating element.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 4","pages":"Article 149563"},"PeriodicalIF":3.4,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144481769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondrial reactive oxygen species production in lungs of rats with different susceptibilities to hyperoxia-induced acute lung injury","authors":"Pardis Taheri ,&nbsp;Devanshi D. Dave ,&nbsp;Abraham Taye ,&nbsp;Anne V. Clough ,&nbsp;Elizabeth R. Jacobs ,&nbsp;Ranjan K. Dash ,&nbsp;Said H. Audi","doi":"10.1016/j.bbabio.2025.149561","DOIUrl":"10.1016/j.bbabio.2025.149561","url":null,"abstract":"<div><div>Adult rats exposed to hyperoxia (&gt;95 % O₂) die within 60–72 h from respiratory failure. However, when preconditioned with either &gt;95 % O₂ for 48 h followed by 24 h in room air (H-T) or 60 % O₂ for 7 days (H-S), they acquire tolerance or susceptibility to hyperoxia, respectively. The aim was to quantify H₂O₂ production rate and identify sources in isolated lung mitochondria and isolated perfused lungs (IPLs) of normoxia, H-T, and H-S rats. Mitochondria were isolated from lungs, and H₂O₂ production rates were quantified in the presence of pyruvate-malate or succinate, with and without inhibitors of mitochondrial complex I (CI), complex II (CII), and/or H₂O₂ scavenging systems. Lung rate of H₂O₂ release was quantified in IPLs with and without CII inhibitor. Results from isolated mitochondria show that CII is the main H₂O₂ source, and that both H₂O₂ production rate and scavenging capacity were ~48 % lower in H-S mitochondria compared to normoxia. Results from IPLs show that CII is also the dominant H₂O₂ source from lung tissue, and that H₂O₂ release rate was lower in H-T lungs compared to normoxia and H-S lungs. These results suggest that for H-S rats, both mitochondrial rate of H₂O₂ production and scavenging capacity were significantly lower than those in normoxia mitochondria and may contribute to their increased hyperoxia susceptibility. The lower H₂O₂ release rate from H-T IPLs, along with no change in mitochondrial H₂O₂ production rate, is consistent with higher antioxidant capacity in the lungs of H-T rats, which may contribute to their hyperoxia tolerance.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 4","pages":"Article 149561"},"PeriodicalIF":3.4,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144295269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antarctic photosynthesis: energy transfer and charge separation in the diatom Chaetoceros simplex","authors":"Shu En Lee ,&nbsp;Willem van de Poll ,&nbsp;Volha Chukhutsina","doi":"10.1016/j.bbabio.2025.149560","DOIUrl":"10.1016/j.bbabio.2025.149560","url":null,"abstract":"<div><div>The polar oceanic environment poses extreme challenges to photosynthetic organisms, which have evolved atypical strategies to maintain efficient photosynthesis in cold temperatures. Here, the psychrophilic diatom <em>Chaetoceros simplex</em> (<em>C. simplex</em>) is studied <em>in vivo</em> in the dark-adapted state using steady-state and time-resolved fluorescence methods. Our results show that all fucoxanthin chlorophyll <em>a</em>/c protein (FCP) antenna transfer energy to photosystem I (PSI) or photosystem II (PSII), with no detached FCPs. PSI exhibits no fluorescence of ‘red’ forms of chlorophyll (chl) beyond 700 nm in both 279 K and 77 K conditions. Despite this, it apparently has a long decay time of ~85 ps indicating the presence of a large core-antenna supercomplex. PSII has an average lifetime of ~500 ps in open state (Q_A oxidized) and ~1220 ps in closed state (Q_A reduced). PSII of <em>C. simplex</em> has kinetics that are slightly slower than temperate diatoms, suggesting larger antenna. In addition, fucoxanthin (fx) molecules of FCP that absorb in the 500–550 nm range (fx-red) transfer more energy to PSII than fx that absorb in the blue range (fx-blue, 462 nm max absorption). A subpopulation of red-shifted, aggregated FCPs are detected at 77 K, that are active in energy transfer uphill at 279 K. Overall, our results indicate relatively larger antenna of PSI and PSII and an absence of red chls in PSI of cold-adapted species, compared to temperate species.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 3","pages":"Article 149560"},"PeriodicalIF":3.4,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144183016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adenine nucleotide-dependent Ca2+ buffering by mitochondria in an inorganic phosphate-free medium","authors":"Anna.B. Nikiforova,&nbsp;Maxim.V. Molchanov,&nbsp;Alexey G. Kruglov","doi":"10.1016/j.bbabio.2025.149559","DOIUrl":"10.1016/j.bbabio.2025.149559","url":null,"abstract":"<div><div>Inorganic phosphate (P_i) is essential for Ca²⁺ buffering by mitochondria. Adenine nucleotides (AN) are known to strongly increase the Ca²⁺-retention capacity (CRC) of mitochondria even in the absence of P_i in the medium. Several mechanisms can explain this phenomenon. Here we examined these mechanisms in detail in isolated rat liver mitochondria. We found that, in P_i-free medium, AN dose-dependently increased the CRC. The F_OF₁-ATP synthase (F-ATPase) inhibitor oligomycin decreased the CRC and the Ca²⁺ uptake rate to a minor extent. Nuclear magnetic resonance (NMR) analysis showed that P_i in suspensions of oligomycin-treated mitochondria was formed due to AN hydrolysis. In the absence and presence of Ca²⁺, mitochondria accumulated small and large (50 and &gt; 1000 nmol/mg protein) amounts of Pi, respectively, without detectable accumulation of AN. The average ratio of Ca²⁺ to P_i accumulated by intact mitochondria in the presence of ADP, ATP, and ATP plus P_i was about 0.68, 1, and 1.25, respectively, or lower. These values correspond to the formation of calcium dihydrogen and hydrogen orthophosphates, and tricalcium phosphate/whitlockite in different proportions. AN increased the CRC in the presence of inhibitors of both F-ATPase and adenylate translocase, the known regulators of the permeability transition pore (PTP). The PTP inhibitor NADH did not increase the CRC in the absence of P_i. Thus, the mechanism of the AN-dependent increase in the CRC in the absence of P_i includes the F-ATPase-independent production of P_i and suppression of the PTP at the site other than F-ATPase and adenylate translocase.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 3","pages":"Article 149559"},"PeriodicalIF":3.4,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144146874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to “New insights into the involvement of residue D1/V185 in Photosystem II function in Synechocystis 6803 and Thermosynechococcus vestitus” [Biochim. Biophys. Acta Bioenerg. 1866 (2025) 149550]","authors":"Alain Boussac ,&nbsp;Julien Sellés ,&nbsp;Tania Tibiletti ,&nbsp;Miwa Sugiura ,&nbsp;Robert L. Burnap","doi":"10.1016/j.bbabio.2025.149558","DOIUrl":"10.1016/j.bbabio.2025.149558","url":null,"abstract":"","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 3","pages":"Article 149558"},"PeriodicalIF":3.4,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144163501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential effects of the D1/S264V mutation in photosystem II with either PsbA1 or PsbA3 on QB, non-heme Iron, and the associated hydrogen-bond network","authors":"Kosuke Tada ,&nbsp;Kaho Yamagata ,&nbsp;Kazumi Koyama ,&nbsp;Julien Sellés ,&nbsp;Alain Boussac ,&nbsp;Miwa Sugiura","doi":"10.1016/j.bbabio.2025.149557","DOIUrl":"10.1016/j.bbabio.2025.149557","url":null,"abstract":"<div><div>The role of the D1/S264 residue and the role of its environment in the proton-coupled electron transfer reaction on the acceptor side of Photosystem II were investigated. To this end, D1/S264V mutants were constructed in the thermophilic cyanobacterium <em>Thermosynechococcus elongatus</em>, with D1 being either PsbA1 or PsbA3. The PSII mutants were investigated using EPR spectroscopy, thermoluminescence, (time-resolved) absorption changes measurements, and oximetry. While the mutation had minor effects in PsbA1-PSII, the S264V mutation in PsbA3-PSII had significant consequences: <em>i</em>) thermoluminescence data show inefficient electron transfer from Q_A⁻ to Q_B; <em>ii</em>) re-oxidation of Q_A⁻ was slowed, by at least a factor of 10; <em>iii</em>) the herbicides inhibit weakly O₂ evolution; <em>iv</em>) no Fe²⁺Q_B⁻ EPR signal was detected in dark-adapted PSII; instead, <em>v</em>) a large Fe³⁺ signal was present with <em>vi</em>) modified EPR properties; <em>vii</em>) no Q_A⁻Fe²⁺Q_B⁻ biradical signal was observed after illumination at 198 K following a flash illumination, confirming the inefficient formation of Q_B⁻; <em>viii</em>) either no proton uptake coupled to non-heme iron reduction occurred or with a very slow rate compared to PsbA3-PSII; <em>ix</em>) changes were noted in the electrochromic response associated with Q_A⁻ formation; and <em>x</em>) increased production of singlet oxygen, both with and without herbicides. The S264V mutation in PsbA3-PSII leads to a significant decrease in the energy gap between the Q_A⁻Q_B and Q_AQ_B⁻ states. The effects listed above are discussed regarding the differences between PsbA1-PSII and PsbA3-PSII as those related to the sulfoquinovosyldiacylglycerol, the water molecules and the H-bond network.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 3","pages":"Article 149557"},"PeriodicalIF":3.4,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144116512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of retinal chromophore photoisomerization in enhanced inward proton-pumping activity of xenorhodopsin from Nanosalina","authors":"Yuma Ito ,&nbsp;Tatsuro Nishikino ,&nbsp;Hideki Kandori ,&nbsp;Yuji Furutani","doi":"10.1016/j.bbabio.2025.149556","DOIUrl":"10.1016/j.bbabio.2025.149556","url":null,"abstract":"<div><div>Xenorhodopsin (XeR) is the first identified light-driven inward proton pump, exhibiting proton translocation vectoriality opposite to that of bacteriorhodopsin (BR)—a well-characterized outward proton pump rhodopsin. The molecular mechanism governing this vectoriality remains a fundamental question. A distinguishing feature of XeRs is the substitution of the second counterion (Asp212 in BR) with a proline residue located near the protonated retinal Schiff base (PRSB). The absence of a negatively charged residue in XeRs may hinder proton transfer from the Schiff base to the primary counterion (Asp85 in BR), a key determinant of vectoriality. Several studies have reported that XeR from <em>Nanosalina</em> (<em>Ns</em>XeR) exhibits higher inward proton-pumping activity than other XeRs, although the underlying molecular mechanism remains unclear. In this study, we analyzed the early photointermediate (K) of <em>Ns</em>XeR using light-induced difference Fourier transform infrared spectroscopy, revealing two characteristic features. First, the distinct hydrogen out-of-plane (HOOP) vibrations—indicative of retinal distortion—were absent, suggesting a minimally distorted retinal chromophore post-photoisomerization in <em>Ns</em>XeR. Second, the PRSB exhibited a weaker hydrogen bond in the dark state. Interestingly, substituting Pro209 at the second counterion position with alanine or glycine (P209A and P209G) restored HOOP band intensity and strengthened the PRSB hydrogen bond. Importantly, the P209A and P209G mutants demonstrated reduced inward proton-pumping activity and slower recovery in the final thermal isomerization process compared to the wild type. These findings suggest that photoisomerization without retinal distortion enhances inward proton transport in <em>Ns</em>XeR.</div></div>","PeriodicalId":50731,"journal":{"name":"Biochimica et Biophysica Acta-Bioenergetics","volume":"1866 3","pages":"Article 149556"},"PeriodicalIF":3.4,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}