The [NiFe]-hydrogenase accessory chaperones HypC and HybG of Escherichia coli are iron- and carbon dioxide-binding proteins

Abstract[NiFe]-hydrogenase accessory proteins HypC and HypD form a complex that binds a Fe–(CN)2CO moiety and CO2. In this study two HypC homologues from Escherichia coli were purified under strictly anaerobic conditions and both contained sub-stoichiometric amounts of iron (approx. 0.3molFe/mol HypC). Infrared spectroscopic analysis identified a signature at 2337cm−1 indicating bound CO2. Aerobically isolated HypC lacked both Fe and CO2. Exchange of either of the highly conserved amino acid residues Cys2 or His51 abolished both Fe- and CO2-binding. Our results suggest that HypC delivers CO2 bound directly to Fe for reduction to CO by HypD.Structured summary of protein interactionsHypC and HypC bind by comigration in sds page (View interaction)HybG and HybG bind by comigration in sds page (View interaction