title: Influence of tyrosine-kinase Wzc activity on colanic acid production in Escherichia coli K12 cells.
abstract: Bacterial tyrosine-kinases have been demonstrated to participate in the regulation of capsule polysaccharides (CPS) and exopolysaccharides (EPS) production and export. However, discrepant data have been reported on the molecular mechanism responsible for this regulation depending on the bacterial species analyzed. Special attention was previously paid to the tyrosine-kinase Wzc(ca) of Escherichia coli K-12, which is involved in the production of the exopolysaccharide, colanic acid, and autophosphorylates by using a cooperative two-step process. In this work, we took advantage of these observations to investigate in further detail the effect of Wzc(ca) phosphorylation on the colanic acid production. First, it is shown that expression of the phosphorylated form of Wzc prevents production of colanic acid whereas expression of the non-phosphorylated form allows biosynthesis of this exopolysaccharide. However, we provide evidence that, in the latter case, the size distribution of the colanic acid polymer is less scattered than in the case of the wild-type strain expressing both phosphorylated and non-phosphorylated forms of Wzc. It is then demonstrated that colanic acid production is not merely regulated by an on/off mechanism and that, instead, both phosphorylated and non-phosphorylated forms of Wzc are required to promote colanic acid synthesis. Moreover, a series of data suggests that besides the involvement of phosphorylated and non-phosphorylated forms of Wzc in the production of colanic acid, two particular regions of this kinase play as such an important role in the synthesis of this exopolysaccharide: a proline-rich domain located in the N-terminal part of Wzc(ca), and a tyrosine cluster present in the C-terminal portion of the enzyme. Furthermore, considering that polysaccharides are known to facilitate bacterial resistance to certain environmental stresses, it is shown that the resistance of E. coli to desiccation is directly connected with the phosphorylation state of Wzc(ca).
authors.affiliation: Institute of Biology and Chemistry of Proteins, University of Lyon, CNRS, 69367 Lyon, France.
authors.forename: Brice
authors.initials: B
authors.lastname: Obadia
authors.forename: Soline
authors.initials: S
authors.lastname: Lacour
authors.forename: Patricia
authors.initials: P
authors.lastname: Doublet
authors.forename: Hélène
authors.initials: H
authors.lastname: Baubichon-Cortay
authors.forename: Alain J
authors.initials: AJ
authors.lastname: Cozzone
authors.forename: Christophe
authors.initials: C
authors.lastname: Grangeasse
mesh_terms: D048168:Escherichia coli K12 / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D008970:Molecular Weight; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011134:Polysaccharides / Q000096:biosynthesis*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011134:Polysaccharides; C004275:colanic acid; D011505:Protein-Tyrosine Kinases; C499615:wzc protein, E coli; D010744:Phosphoric Monoester Hydrolases