The Role of A NifS-Like Protein in the Biogenesis of FeS Proteins in Cyanobacteria

Abstract

Proteins containing FeS centres are involved in many cellular processes such as electron transfer, catalysis and regulation, yet the mechanism of their biogenesis remains poorly understood. In Azotobacter vinelandii it has been shown that NifS is involved in the synthesis of the FeS centres of nitrogenase (1–4). NifS is a pyridoxal phosphate-dependent protein which transforms cysteine into alanine and elementary sulphur. This sulphur is transiently bound to a specific cysteine side chain and becomes then incorporated into FeS centres by an unknown mechanism (2–4). More recently, from the same organism and from E.coli proteins with a high homology to NifS have been isolated which are involved in FeS cluster synthesis of proteins other than nitrogenase (5, 6). Therefore, NifS-like proteins seem to be involved not only in the synthesis of FeS clusters of nitrogenase but also of other FeS proteins, even in organisms which do not fix nitrogen.