title: Suppression and synthetic-lethal genetic relationships of ΔgpsB mutations indicate that GpsB mediates protein phosphorylation and penicillin-binding protein interactions in Streptococcus pneumoniae D39.
abstract: GpsB regulatory protein and StkP protein kinase have been proposed as molecular switches that balance septal and peripheral (side-wall like) peptidoglycan (PG) synthesis in Streptococcus pneumoniae (pneumococcus); yet, mechanisms of this switching remain unknown. We report that ΔdivIVA mutations are not epistatic to ΔgpsB division-protein mutations in progenitor D39 and related genetic backgrounds; nor is GpsB required for StkP localization or FDAA labeling at septal division rings. However, we confirm that reduction of GpsB amount leads to decreased protein phosphorylation by StkP and report that the essentiality of ΔgpsB mutations is suppressed by inactivation of PhpP protein phosphatase, which concomitantly restores protein phosphorylation levels. ΔgpsB mutations are also suppressed by other classes of mutations, including one that eliminates protein phosphorylation and may alter division. Moreover, ΔgpsB mutations are synthetically lethal with Δpbp1a, but not Δpbp2a or Δpbp1b mutations, suggesting GpsB activation of PBP2a activity. Consistent with this result, co-IP experiments showed that GpsB complexes with EzrA, StkP, PBP2a, PBP2b and MreC in pneumococcal cells. Furthermore, depletion of GpsB prevents PBP2x migration to septal centers. These results support a model in which GpsB negatively regulates peripheral PG synthesis by PBP2b and positively regulates septal ring closure through its interactions with StkP-PBP2x.
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Britta E
authors.initials: BE
authors.lastname: Rued
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Jiaqi J
authors.initials: JJ
authors.lastname: Zheng
authors.affiliation: Dipartimento di Scienze Chirurgiche, Università di Cagliari, Cagliari, 09100, Italy.|Cell and Molecular Microbiology Division, Institute of Microbiology, v.v.i, Academy of Sciences of the Czech Republic, Prague 4, 142 20, Czech Republic.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mura
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Ho-Ching T
authors.initials: HT
authors.lastname: Tsui
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Boersma
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Mazny
authors.affiliation: Dipartimento di Scienze Chirurgiche, Università di Cagliari, Cagliari, 09100, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Corona
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Amilcar J
authors.initials: AJ
authors.lastname: Perez
authors.affiliation: Dipartimento di Scienze Chirurgiche, Università di Cagliari, Cagliari, 09100, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Fadda
authors.affiliation: Cell and Molecular Microbiology Division, Institute of Microbiology, v.v.i, Academy of Sciences of the Czech Republic, Prague 4, 142 20, Czech Republic.
authors.forename: Linda
authors.initials: L
authors.lastname: Doubravová
authors.affiliation: Cell and Molecular Microbiology Division, Institute of Microbiology, v.v.i, Academy of Sciences of the Czech Republic, Prague 4, 142 20, Czech Republic.
authors.forename: Karolína
authors.initials: K
authors.lastname: Buriánková
authors.affiliation: Cell and Molecular Microbiology Division, Institute of Microbiology, v.v.i, Academy of Sciences of the Czech Republic, Prague 4, 142 20, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Branny
authors.affiliation: Dipartimento di Scienze Chirurgiche, Università di Cagliari, Cagliari, 09100, Italy.
authors.forename: Orietta
authors.identifier: 0000-0001-8823-2372
authors.initials: O
authors.lastname: Massidda
authors.affiliation: Department of Biology, Indiana University Bloomington, Bloomington, IN 47405, USA.
authors.forename: Malcolm E
authors.identifier: 0000-0002-1482-2588
authors.initials: ME
authors.lastname: Winkler
mesh_terms: D019881:Aminoacyltransferases / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001482:Base Composition / Q000235:genetics; D002455:Cell Division / Q000235:genetics* / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D046915:Penicillin-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis*; D010766:Phosphorylation; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C000621702:GpsB protein, Streptococcus pneumoniae; D008565:Membrane Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan; D037521:Virulence Factors; D019881:Aminoacyltransferases; C478701:penicillin-binding protein 2b, Streptococcus