Mutational dissection of the S/T-kinase StkP reveals crucial roles in cell division of Streptococcus pneumoniae.
Eukaryotic-like serine/threonine-kinases are involved in the regulation of a variety of physiological processes in bacteria. In Streptococcus pneumoniae, deletion of the single serine/threonine-kinase gene stkP results in an aberrant cell morphology suggesting that StkP participates in pneumococcus cell division. To understand the function of StkP, we have engineered various pneumococcus strains expressing truncated or kinase-dead forms of StkP. We show that StkP kinase activity, but also its extracellular and cytoplasmic domains per se, are required for pneumococcus cell division. Indeed, we observe that mutant cells show round or elongated shapes with non-functional septa and a chain phenotype, delocalized sites of peptidoglycan synthesis and diffused membrane StkP localization. To gain understanding of the underlying StkP-mediated regulatory mechanism, we show that StkP specifically phosphorylates in vivo the cell division protein DivIVA on threonine 201. Pneumococcus cells expressing non-phosphorylatable DivIVA-T201A possess an elongated shape with a polar bulge and aberrant spatial organization of nascent peptidoglycan. This brings the first evidence of the importance of StkP in relationship to the phosphorylation of one of its substrates in cell division. It is concluded that StkP is a multifunctional protein that plays crucial functions in pneumococcus cell shape and division.
Bases Moléculaires et Structurales des Systèmes Infectieux, IBCP, Université Lyon 1, CNRS, Université de Lyon, UMR 5086, 7 passage du Vercors, 69367 Lyon, France.
Aurore
A
Fleurie
Caroline
C
Cluzel
Sébastien
S
Guiral
Céline
C
Freton
Frédéric
F
Galisson
Isabelle
I
Zanella-Cleon
Anne-Marie
AM
Di Guilmi
Christophe
C
Grangeasse
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D004252:DNA Mutational Analysis; D008853:Microscopy; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; C104636:DivIVA protein, bacteria; D050505:Mutant Proteins; D017346:Protein Serine-Threonine Kinases