Abstract
It is reported that IscS (a homolog of NifS) and IscU protein in Azotobacter vinelandii and Escherichia coli are involved in assembly of iron sulfur (FeS) proteins. It is thought that mobilizing sulfur from free cystein is incorporated into apo-FeS protein to form FeS cluster by IscS and that IscU play a role as scaffold protein. IscS and IscU homolog were also reported from oxygenic photosyntetic bacteria, cyanobacteria Synechosystis PCC 6803. Whole genome sequence of Green sulfur Bacterium Chlorobium tepidum revealed that the putative iscS iscU are present on the genome. Phylogenetic analysis indicated that the iscS of C. tepidum is classified with different from that of E. coli and cyanobacteria. To investigate the function of iscS and iscU of C. tepidum, we over-expressed this genes in E. coli. The biochemical function of purified proteins from E. coli will be reported.
