Phosphorylation of the juxta-membrane domain of the membrane serine/threonine-kinase StkP and characterization of the impact on the cell cycle of Streptococcus pneumoniae

ABSTRACT: StkP is the single membrane serine/threonine kinase encoded by the human bacterial pathogen Streptococcus pneumoniae. This protein-kinase is considered to be a key regulator of pneumococcal cell division and morphogenesis. In particular, it phosphorylates and/or interacts with several key cell division proteins to control cell elongation, cell constriction and the final separation of daughter cells. A long-standing question concerns the mode of activation of StkP. Even if, it is proposed that StkP activity could be triggered by an extracellular stimulus from the bacterial cell wall, how StkP carries out the phosphorylation of its substrates in response to this stimulus remains enigmatic. It is proposed that the flexible and intrinsically disordered juxta-membrane domain (JMD) of StkP, which connects the cytoplasmic catalytic domain to the transmembrane span, plays a critical role in StkP activation. Our preliminary experiments showed that when the JMD is deleted, StkP is inactive and unable to phosphorylate its cellular targets in vivo. Importantly, several phosphoproteomic studies performed in other bacterial models have shown that some amino acids of the JMD are phosphorylated, suggesting that StkP JMD phosphorylation could also be key for StkP activation. To test this, we wanted to perform a comprehensive identification of the potential phosphorylation sites within the JMD. For that, we purified StkP from Streptococcus pneumoniae and characterized all the amino acids phosphorylated inside de JMD by mass spectrometry. We will then evaluate the impact of the phosphorylation sites on the activation of StkP and its ability to regulate cell division.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Streptococcus Pneumoniae (strain Atcc Baa-255 / R6)

SUBMITTER: Vaishnavi Ravikumar  

LAB HEAD: Ivan Mijakovic

PROVIDER: PXD052685 | Pride | 2025-03-20

REPOSITORIES: Pride