title: The Kil peptide of bacteriophage λ blocks Escherichia coli cytokinesis via ZipA-dependent inhibition of FtsZ assembly.
abstract: Assembly of the essential, tubulin-like FtsZ protein into a ring-shaped structure at the nascent division site determines the timing and position of cytokinesis in most bacteria and serves as a scaffold for recruitment of the cell division machinery. Here we report that expression of bacteriophage λ kil, either from a resident phage or from a plasmid, induces filamentation of Escherichia coli cells by rapid inhibition of FtsZ ring formation. Mutant alleles of ftsZ resistant to the Kil protein map to the FtsZ polymer subunit interface, stabilize FtsZ ring assembly, and confer increased resistance to endogenous FtsZ inhibitors, consistent with Kil inhibiting FtsZ assembly. Cells with the normally essential cell division gene zipA deleted (in a modified background) display normal FtsZ rings after kil expression, suggesting that ZipA is required for Kil-mediated inhibition of FtsZ rings in vivo. In support of this model, point mutations in the C-terminal FtsZ-interaction domain of ZipA abrogate Kil activity without discernibly altering FtsZ-ZipA interactions. An affinity-tagged-Kil derivative interacts with both FtsZ and ZipA, and inhibits sedimentation of FtsZ filament bundles in vitro. Together, these data inspire a model in which Kil interacts with FtsZ and ZipA in the cell to prevent FtsZ assembly into a coherent, division-competent ring structure. Phage growth assays show that kil+ phage lyse ∼30% later than kil mutant phage, suggesting that Kil delays lysis, perhaps via its interaction with FtsZ and ZipA.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, United States of America.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Haeusser
authors.affiliation: National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: Marina
authors.initials: M
authors.lastname: Hoashi
authors.affiliation: National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: Anna
authors.initials: A
authors.lastname: Weaver
authors.affiliation: National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: Nathan
authors.initials: N
authors.lastname: Brown
authors.affiliation: National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Pan
authors.affiliation: National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: James A
authors.initials: JA
authors.lastname: Sawitzke
authors.affiliation: Frederick National Laboratory for Cancer Research, Leidos Biomedical, Inc., Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Thomason
authors.affiliation: National Cancer Institute at Frederick, Gene Regulation and Chromosome Biology Laboratory, Frederick, Maryland, United States of America.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Court
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, United States of America.
authors.forename: William
authors.initials: W
authors.lastname: Margolin
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics*; D048749:Cytokinesis / Q000235:genetics*; D003598:Cytoskeletal Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics*; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; C071525:FtsZ protein, Bacteria; D010455:Peptides; D014764:Viral Proteins; C103795:ZipA protein, E coli; C121561:kil protein, bacteriophage P4