title: An essential tyrosine phosphatase homolog regulates cell separation, outer membrane integrity, and morphology in Caulobacter crescentus.
abstract: Although reversible phosphorylation on tyrosine residues regulates the activity of many eukaryotic proteins, there are few examples of this type of regulation in bacteria. We have identified the first essential tyrosine phosphatase homolog in a bacterium, Caulobacter crescentus CtpA. ctpA mutants with altered active-site residues are nonviable, and depletion of CtpA yields chains of cells with blebbed outer membranes, linked by unresolved peptidoglycan. CtpA overexpression reduces cell curvature in a manner similar to deleting the intermediate filament protein crescentin, but it does not disrupt crescentin localization or membrane attachment. Although it has no obvious signal sequence or transmembrane-spanning domains, CtpA associates with the Caulobacter inner membrane. Immunolocalization experiments suggest that CtpA accumulates at the division site during the last quarter of the cell cycle. We propose that CtpA dephosphorylates one or more proteins involved in peptidoglycan biosynthesis or remodeling, which in turn affect cell separation, cell envelope integrity, and vibrioid morphology.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Elaine B
authors.initials: EB
authors.lastname: Shapland
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Reisinger
authors.forename: Amrita K
authors.initials: AK
authors.lastname: Bajwa
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Ryan
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000201:enzymology / Q000235:genetics*; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D020043:Genes, Essential; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism; D050296:Microbial Viability; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation; D010457:Peptidoglycan / Q000096:biosynthesis; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D001425:Bacterial Outer Membrane Proteins; D007381:Intermediate Filament Proteins; D010457:Peptidoglycan; D017027:Protein Tyrosine Phosphatases