title: Microcin PDI regulation and proteolytic cleavage are unique among known microcins.
abstract: Microcin PDI inhibits a diversity of pathogenic Escherichia coli through the action of an effector protein, McpM. In this study we demonstrated that expression of the inhibitory phenotype is induced under low osmolarity conditions and expression is primarily controlled by the EnvZ/OmpR two-component regulatory system. Functional, mutagenesis and complementation experiments were used to empirically demonstrate that EnvZ is required for the inhibitory phenotype and that regulation of mcpM is dependent on binding of the phosphorylated OmpR to the mcpM promoter region. The phosphorylated OmpR may recognize three different binding sites within this promoter region. Site-directed mutagenesis revealed that the McpM precursor peptide includes two leader peptides that undergo sequential cleavage at positions G17/G18 and G35/A36 during export through the type I secretion system. Competition assays showed that both cleaved products are required for the PDI phenotype although we could not distinguish loss of function from loss of secretion in these assays. McpM has four cysteines within the mature peptide and site-directed mutagenesis experiments demonstrated that the first two cysteines are necessary for McpM to inhibit susceptible cells. Together these data combined with previous work indicate that MccPDI is unique amongst the microcins that have been described to date.
authors.affiliation: College of Oceanography, Hohai University, Nanjing, 210098, P.R.China.|Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Orfe
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Jinxin
authors.initials: J
authors.lastname: Liu
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Shao-Yeh
authors.initials: SY
authors.lastname: Lu
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA.|Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Besser
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, 99164, USA.|Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, 99164, USA.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Call
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001430:Bacteriocins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D009097:Multienzyme Complexes / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021381:Protein Transport; D059748:Proteolysis; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001430:Bacteriocins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D010446:Peptide Fragments; D015534:Trans-Activators; C112177:osmolarity response regulator proteins; C020411:microcin; C057843:envZ protein, E coli