The relA protein of B. subtilis is physically and functionally similar to the relA protein of E. coli . B.subtilis- relA were found to share high homology. Thus we are now focusing on the conserved regions between them, in attempt to define and characterize the regions that are important for relA activity and control in E. coli and B. subtilis . The E. coli relA gene is part of an operon in which a pair of genes called mazE and mazF are located downstream from the relA gene. Sequence analysis revealed that the predicted protein products of mazE and mazF are partially homologous to these of the addiction module which is borne by plasmid R100.
Addiction modules are genetic systems which mediate programmed cell death in bacteria.
Research Projects 1. This suggests a model for programmed cell death in E. coli . Under conditions of nutritional starvation, the level of ppGpp increases. Because mazE is a labile protein, its cellular concentration is decreased more rapidly then that of mazF , and thereby mazF can exerts its toxic effect and cause cell death. Our results support this model.