期刊
STRUCTURE
卷 21, 期 1, 页码 184-190出版社
CELL PRESS
DOI: 10.1016/j.str.2012.11.010
关键词
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资金
- Agence National de la Recherche
- CEA
- CNRS
- Biological and Biotechnological Sciences Research Council [H003878-1]
- Merton College, Oxford, UK
- BBSRC [BB/H003878/1, BB/I022309/1, BB/H001190/1] Funding Source: UKRI
- EPSRC [EP/H019480/1] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BB/H003878/1, BB/I022309/1, BB/H001190/1] Funding Source: researchfish
- Engineering and Physical Sciences Research Council [EP/H019480/1] Funding Source: researchfish
We report the 3.3 angstrom resolution structure of dimeric membrane-bound O-2-tolerant hydrogenase 1 from Escherichia coli in a 2:1 complex with its physiological partner, cytochrome b. From the short distance between distal [Fe4S4] clusters, we predict rapid transfer of H-2-derived electrons between hydrogenase heterodimers. Thus, under low O-2 levels, a functional active site in one heterodimer can reductively reactivate its O-2-exposed counterpart in the other. Hydrogenase 1 is maximally expressed during fermentation, when electron acceptors are scarce. These conditions are achieved in the lower part of the host's intestinal tract when E. coli is soon to be excreted and undergo an anaerobic-to-aerobic metabolic transition. The apparent paradox of having an O-2-tolerant hydrogenase expressed under anoxia makes sense if the enzyme functions to keep intracellular O-2 levels low by reducing it to water, protecting O-2-sensitive enzymes during the transition. Cytochrome b's main role may be anchoring the hydrogenase to the membrane.
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