The topoisomerase IV ParE is a target of multiple Fic proteins    
C. LU (1), E. Nakayasu (2), A. McCloskey (3), L. Zhang (4), Z. Luo (3) (1) Chian Agurictural University; Purdue University, U.S.A.; (2) Biological Sciences Division, Pacific Northwest National Laboratory, U.S.A.; (3) Purdue Institute for Inflammation, Immunology and Infectious Disease and Department of Biological Sciences, Purdue University, U.S.A.; (4) Department of Plant Pathology, China Agricultural University, China

       The Fic (filamentation induced by cyclic AMP) domain is a widely distributed motif with a conserved sequence of HPFx[D/E]GN[G/K]R, many of which catalyze the transfer of the AMP moiety of ATP to substrates that often contain an ATPase or GTPase domain. Three putative fic genes are present in the genome of the biocontrol Pseudomonas fluorescens strain 2P24. Recently we showed that Fic-1 from this strain inhibits bacterial DNA replication by AMPylating the subunit B of gyrase at Tyr111, inducing the SOS response and cell filamentation. Fic-1 also induced cell elongation in strains defective in the SOS pathway, suggesting that it may target other proteins involved in this aspect of bacterial morphology. Further analysis found that Fic-1 interacts with the topoisomerase IV ParE, which was AMPylated at residue Tyr109, a position that corresponds to Tyr105 of its Escherichia coli counterpart. Interestingly, a constitutively active mutant of Fic-2 from P. fluorescens defective in the inhibitory motif also AMPylates ParE but not GyrB. Furthermore, when Fic proteins from phylogenetically diverse bacteria were tested, those from Yersinia pseudotuberculosis, Staphylococcus aureus modified ParE by AMPylation. In contrast, Fic proteins from Pseudomonas aeruginosa, Mycobacterium or Streptococcus pneumoniae modified neither GyrB nor ParE. The canonical par phenotypes featured by the assembly of nucleoid in the middle of the cells and cell elongation were induced by these ParE-targeting Fic proteins or by the ParEY109A mutants. Our results suggest that Fic proteins target the topoisomerase IV ParE to regulate processes such as DNA replication, chromosome division and cell separation.

Abstract Number: P5-124
Session Type: Poster