The cell division protein FtsZ from Streptococcus pneumoniae exhibits a GTPase activity delay

© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.. The cell division protein FtsZ assembles in vitro by a mechanism of cooperative association dependent on GTP, monovalent cations, and Mg2+. We have analyzed the GTPase activity and assembly dynamics of Streptococcus pneumoniae FtsZ (Spn-FtsZ). SpnFtsZ assembled in an apparently cooperative process, with a higher critical concentration than values reported for other FtsZ proteins. It sedimented in the presence of GTP as a high molecular mass polymer with a well defined size and tended to form double-stranded filaments in electron microscope preparations. GTPase activity depended on K+ and Mg2+ and was inhibited by Na+. GTP hydrolysis exhibited a delay that included a lag phase followed by a GTP hydrolysis activation step, until reaction reached the GTPase rate. The lag phase was not found in polymer assembly, suggesting a transition from an initial non-GTP-hydrolyzing polymer that switches to a GTP-hydrolyzing polymer, supporting models that explain FtsZ polymer cooperativity.Spanish Government GrantsBIO2011-28941-C03 (to G. R. and C. A.) and BIO2011-28941-C01; Torres Quevedo Program Grant PTQ-11-05049 to Biomol Informatics S.L.Peer Reviewe