EVOLUTION OF HYDROGENASE GENES

This chapter discusses the evolution of hydrogenase genes. All hydrogenases studied with molecular biological techniques to date consist of at least two subunits. The structural genes encoding these subunits are organized in an operon with the gene order (5' → 3'). Nucleotide sequencing has indicated the presence of additional genes in the operon—for example, hydrogenase 1 of Escherichia coli (E. coli) is encoded by an operon encoding six open reading frames. Two of these (hyaA and hyaB) encode the small and large subunits that constitute this hydrogenase as it is isolated from E. coli. The function of the products of the other four genes (hyaC–hyaF) has not yet been established. They could function in anchoring the two-subunit hydrogenase to the membrane and in conducting electrons to the membrane-bound electron transport chain. © 1992, Academic Press, Inc.