Mycobacterium smegtatis phosphoproteomics LC-MS/MS

ABSTRACT: Protein phosphatase PstP is conserved throughout the Actinobacteria in a genetic locus related to cell wall synthesis and cell division. In many Actinobacteria it is the sole annotated serine threonine protein phosphatase to counter the activity of multiple serine threonine protein kinases. We used transcriptional knockdown, electron microscopy and comparative phosphoproteomics to investigate the putative dual functions of PstP as a specific regulator of cell division and as a global regulator of protein phosphorylation. pstP knockdown in Mycobacterium smegmatis led to thickening of the cell wall and septum, changes in cell morphology, and eventual cell lysis. Comparative phosphoproteomics in the early stages of PstP depletion showed hyperphosphorylation of protein kinases and their substrates, confirming PstP as a negative regulator of kinase activity and global serine and threonine phosphorylation. Analysis of the 838 phosphorylation sites that changed significantly, suggested that PstP may have broad specificity, with preference for phosphothreonine, phosphosites near acidic residues, near the protein termini, and within membrane associated proteins. Increased phosphorylation of the activation loop of protein kinase B (PknB) and of the essential PknB substrate CwlM offer possible explanations for the essentiality of pstP and the cell wall defects when PstP was depleted.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Mycolicibacterium Smegmatis Mkd8

SUBMITTER: Helen O'Hare  

LAB HEAD: Dr Helen O'Hare

PROVIDER: PXD011805 | Pride | 2019-11-12

REPOSITORIES: Pride