title: Evidence That Bacteriophage λ Kil Peptide Inhibits Bacterial Cell Division by Disrupting FtsZ Protofilaments and Sequestering Protein Subunits.
abstract: The effects of Kil peptide from bacteriophage λ on the assembly of Escherichia coli FtsZ into one subunit thick protofilaments were studied using combined biophysical and biochemical methods. Kil peptide has recently been identified as the factor from bacteriophage λ responsible for the inhibition of bacterial cell division during lytic cycle, targeting FtsZ polymerization. Here, we show that this antagonist blocks FtsZ assembly into GTP-dependent protofilaments, producing a wide distribution of smaller oligomers compared with the average size of the intact protofilaments. The shortening of FtsZ protofilaments by Kil is detectable at concentrations of the peptide in the low micromolar range, the mid-point of the inhibition being close to its apparent affinity for GDP-bound FtsZ. This antagonist not only interferes with FtsZ assembly but also reverses the polymerization reaction. The negative regulation by Kil significantly reduces the GTPase activity of FtsZ protofilaments, and FtsZ polymers assembled in guanosine-5'-[(α,β)-methyleno]triphosphate are considerably less sensitive to Kil. Our results suggest that, at high concentrations, Kil may use an inhibition mechanism involving the sequestration of FtsZ subunits, similar to that described for other inhibitors like the SOS response protein SulA or the moonlighting enzyme OpgH. This mechanism is different from those employed by the division site selection antagonists MinC and SlmA. This work provides new insight into the inhibition of FtsZ assembly by phages, considered potential tools against bacterial infection.
authors.affiliation: From the Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain and.
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Hernández-Rocamora
authors.affiliation: From the Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain and.
authors.forename: Carlos
authors.initials: C
authors.lastname: Alfonso
authors.affiliation: the Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, Texas 77030.
authors.forename: William
authors.initials: W
authors.lastname: Margolin
authors.affiliation: From the Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain and silvia@cib.csic.es.
authors.forename: Silvia
authors.initials: S
authors.lastname: Zorrilla
authors.affiliation: From the Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain and grivas@cib.csic.es.
authors.forename: Germán
authors.initials: G
authors.lastname: Rivas
mesh_terms: D001419:Bacteria / Q000166:cytology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D010582:Bacteriophage lambda / Q000737:chemistry*; D001704:Biopolymers / Q000737:chemistry; D002455:Cell Division / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000502:physiology; D010455:Peptides / Q000502:physiology*; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D010455:Peptides; D014764:Viral Proteins; D006160:Guanosine Triphosphate
keywords: Escherichia coli (E. coli); bacteriophage; biophysics; cell division; protein-protein interaction