Structures of mitochondrial ubihydroquinone:cytochrome c oxidoreductase (bc1 complex) from several animal sources have provided a basis for understanding the functional mechanism at molecular level. Using structures chicken complex with and without inhibitors, we analyze effects mutation on quinol oxidation Qo site complex. We suggest reaction that incorporates two features revealed by structures, movement iron sulfur protein between separate domains cytochrome c1 b bifurcated volume site....

Quinol oxidation by the bc 1 complex of Rhodobacter sphaeroides occurs from an enzyme–substrate formed between quinol bound at Q o site and iron–sulfur protein (ISP) docked interface on cytochrome b . From structure stigmatellin-containing mitochondrial complex, we suggest that hydrogen bonds to two hydroxyl groups, Glu-272 His-161 ISP, help stabilize aid proton release. Reduction oxidized ISP involves H transfer quinol. Release when acceptor chain reoxidizes reduced after domain movement c...

The sodium -pumping NADH: ubiquinone oxidoreductase (Na+-NQR) is the main ion pump and primary entry site for electrons into respiratory chain of many different types pathogenic bacteria. This enzymatic complex creates a transmembrane gradient that used by cell to sustain ionic homeostasis, nutrient transport, ATP synthesis, flagellum rotation other essential processes. Comparative genomics data demonstrate nqr operon, which encodes all Na+-NQR subunits, found in large variety bacterial...

The nqr operon from Vibrio cholerae, encoding the entire six-subunit, membrane-associated, Na+-translocating NADH:quinone oxidoreductase (Na+-NQR), was cloned under regulation of PBAD promoter. enzyme successfully expressed in V. cholerae. To facilitate molecular genetics studies this sodium-pumping enzyme, a host strain cholerae constructed which genomic copy deleted. By using vector containing six-histidine tag on carboxy terminus NqrF subunit, last subunit operon, recombinant readily...

Bacteroides species are abundant in the human intestine and provide numerous beneficial properties to their hosts. The ability of convert host dietary glycans polysaccharides energy is paramount success gut. We know a great deal about molecules that these bacteria extract from gut but much less how they those into energy. Here, we show B. fragilis has complex respiratory pathway with two different enzymes transfer electrons NADH quinone third enzyme may use an electron donor other than NADH....

The Na+-translocating NADH: ubiquinone oxidoreductase (Na+-NQR) generates an electrochemical Na+ potential driven by aerobic respiration. Previous studies on the enzyme from Vibrio alginolyticus have shown that Na+-NQR has six subunits, and it is known to contain FAD FeS center as redox cofactors. In current work, marine bacterium harveyi been purified characterized. addition FAD, a second flavin, tentatively identified FMN, was discovered be covalently attached NqrC subunit. V....

Enzymes of the Rnf family are believed to be bacterial redox-driven ion pumps, coupling an oxidoreduction process translocation Na+ across cell membrane. Here we show for first time that is a flavoprotein, with FMN covalently bound threonine-175 in RnfG and second flavin threonine-187 RnfD. subunits D G homologous B C Na+-NQR, respectively. Each these Na+-NQR includes conserved S(T)GAT motif, final threonine. RnfD both contain same suggesting they bind flavins similar way. In order...

Na + -NQR is a unique respiratory enzyme that couples the free energy of electron transfer reactions to electrogenic pumping sodium across cell membrane. This found in many marine and pathogenic bacteria where it plays an analogous role H -pumping complex I. It has generally been assumed pump operates on basis thermodynamic coupling between reduction single redox cofactor binding at nearby site. In this study, we have defined translocation individual steps reaction -NQR. Sodium uptake takes...

The Na+-pumping NADH:quinone oxidoreductase (Na+-NQR) is the only respiratory enzyme that operates as a Na+ pump. This redox-driven pump amenable to experimental approaches not available for H+ pumps, providing an excellent system mechanistic studies of ion translocation. An understanding internal electron transfer steps and their dependence essential prerequisite such studies. To this end, we analyzed reduction kinetics wild type Na+-NQR, well site-directed mutants enzyme, which lack...

A ferredoxin:NAD(+) oxidoreductase was recently discovered as a redox-driven ion pump in the anaerobic, acetogenic bacterium Acetobacterium woodii. The enzyme is assumed to be encoded by rnf genes. Since these genes are present genomes of many bacteria, we tested for activity cytoplasmic membranes from several different Gram-positive and Gram-negative bacteria that have annotated We found this Clostridium tetanomorphum, ljungdahlii, Bacteroides fragilis, Vibrio cholerae but not Escherichia...

Mechanistic studies of anaerobic gut bacteria have been hindered by the lack a fluorescent protein system to track and visualize proteins dynamic cellular processes in actively growing bacteria. Although underappreciated, many "anaerobes" are able respire using oxygen as terminal electron acceptor. The continually released from epithelial cells creates an gradient mucus layer lumen [L. Albenberg et al., Gastroenterology 147, 1055-1063.e8 (2014)], with available at layer. Here, we show that

Abstract The Na + -pumping NADH-ubiquinone oxidoreductase (Na -NQR) couples electron transfer from NADH to ubiquinone with -pumping, generating an electrochemical gradient that is essential for energy-consuming reactions in bacteria. Since -NQR exclusively found prokaryotes, it a promising target highly selective antibiotics. However, the molecular mechanism of inhibition not well-understood lack atomic structural information about inhibitor-bound state. Here we present cryo-electron...

DNA transfer is ubiquitous in the human gut microbiota, especially among species of order Bacteroidales. In silico analyses have revealed hundreds mobile genetic elements shared between these species, yet little known about phenotypes they encode, their effects on fitness, or pleiotropic consequences for recipient's genome. this work, we show that acquisition a integrative conjugative element (ICE) encoding type VI secretion system (T6SS) shuts down native T6SS

Na+-translocating NADH-ubiquinone oxidoreductase (Na+-NQR) is a unique redox-driven Na+-pump. Since this enzyme exclusively found in prokaryotes, including the human pathogens Vibrio cholerae and Neisseria gonorrhoeae, it promising target for highly selective antibiotics. Korormicin A, natural product, specific potent inhibitor of V. Na+-NQR, may become lead compound relevant drug design. We previously showed that G141A mutation NqrB subunit (NqrB-G141A) confers moderate resistance to...

Na+-NQR is the entry point for electrons into respiratory chain of Vibrio cholerae. It oxidizes NADH, reduces ubiquinone, and uses free energy this redox reaction to translocate sodium across cell membrane. The enzyme a membrane complex six subunits that accommodates 2Fe−2S center several flavins. Both oxidized reduced forms exhibit radical EPR signal. Here, we present ENDOR data demonstrate that, in both enzyme, flavin semiquinone. In neutral flavin, but an anionic where N(5) deprotonated....