Characterization of metalloprotease of Slr0643 and Sll0862，the S2P homologs from Synechocystis sp．PCC6803

Abstract:

Abstract:［Objective］It is a conserved mechanism in bacteria that metalloprotease site-2 protease (S2P) cleaves transmembrane anti-sigma factor to release sequestered sigma factor in response to extracytoplasmic stress． However，the function of site-2 protease homologs in cyanobacteria remains elusive，so we investigated the metalloprotease activity of Slr0643 and Sll0862，the site-2 protease homologs from Synechocystis sp． PCC6803. ［Methods］Recombinant Slr0643 and Sll0862 were constructed and overexpressed in Escherichia coli BL21 (CE3)．Their protease activities were tested against β-casein and then resolved on SDS-PAGE．［Results］Results from caseinolytic assay indicated that Slr0643 and Sll0862 have proteolytic activity which is blocked by o-phenanthroline，a metalloprotease inhibitor． These metalloprotease activity of Slr0643 and Sll0862 in vitro provide the foundation for futher analysis of their substrates in vivo．［Conclusion］The site-2 protease homologs in Synechocystis sp． PCC6803 have metalloprotease activity．