| Type: | Family | Name: | [NiFe]-hydrogenase maturation factor, HypX/HoxX type |
| Description: | [NiFe] hydrogenases function in H2 metabolism in a variety of microorganisms, enabling them to use H2 as a source of reducing equivalent under aerobic and anaerobic conditions [NiFe]hydrogenases consist of two subunits, hydrogenase large and hydrogenase small. The large subunit contains the binuclear [NiFe] active site, while the small subunit binds at least one [4Fe-4S]cluster [].The large subunit of [NiFe]-hydrogenase--as well as other nickel metalloenzymes--is synthesized as a precursor devoid of the metalloenzyme active site. This precursor then undergoes a complex post-translational maturation process that requires a number of accessory proteins [, ].Members of this family, which includes HypX and HoxX, have been shown to be involved in this process [, ], and have been proposed to participate in the generation and transport of the CO and CN ligands [, ]. Interestingly, HypX/HoxX is not present in all hydrogen-metabolizing bacteria. Furthermore, hypX deletion mutants have a reduced but detectable level of hydrogenase activity [, , ].Members of this group have an unusual domain combination: an N-terminal formyl transferase domain and a C-terminal enoyl-CoA hydratase/isomerase domain. So far, no enzymatic reaction is known to combine N10-formyltetrahydrofolate as a C1 donor and acyl-CoA as a substrate [, ].For more information about maturation factors/accessory proteins known to be involved in CN/CO delivery, please see , which describes HypF. | Short Name: | NiFe-hyd_mat_HypX/HoxX |
