舍瓦内拉
电子转移
电子传输链
化学
细胞外
生物物理学
电子受体
黄素组
细胞色素
希瓦氏菌属
氧化还原
结晶学
生物化学
细菌
光化学
生物
无机化学
酶
遗传学
作者
Thomas A. Clarke,Marcus J. Edwards,Andrew J. Gates,Andrea Hall,Gaye F. White,Justin M. Bradley,Catherine L. Reardon,Liang Shi,Alex Beliaev,Matthew J. Marshall,Zheming Wang,Nicholas J. Watmough,James K. Fredrickson,John M. Zachara,Julea N. Butt,David J. Richardson
标识
DOI:10.1073/pnas.1017200108
摘要
Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves decaheme cytochromes that are located on the bacterial cell surface at the termini of trans-outer-membrane electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular intercytochrome electron exchange along “nanowire” appendages. We present a 3.2-Å crystal structure of one of these decaheme cytochromes, MtrF, that allows the spatial organization of the 10 hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65-Å octaheme chain transects the length of the protein and is bisected by a planar 45-Å tetraheme chain that connects two extended Greek key split β-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g., minerals), soluble substrates (e.g., flavins), and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface.
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