Wednesday, February 5, 2025
2/5/2025
ABSTRACT Phosphosignaling provides the major conduit for bacterial adaptation. The two component systems (TCSs) have long been viewed as the canonical phosphosignaling systems in bacteria, but increasingly, O- phosphorylation mediated by Ser/Thr kinases is recognized as a relevant bacterial phosphosignaling mechanism as well. We now show that in fact, Mycobacterium tuberculosis (Mtb) has an expansive, distributed, and cooperative O-phosphorylation system of a size and complexity that is typically only associated with eukaryotes. By using a comprehensive STPK loss- and gain-of-function mutant panel and quantitative mass spectrometry, we show that >70% of Mtb proteins are phosphorylated on Ser/Thr/Tyr, identify thousands of individual Ser/Thr kinase substrates, and show that the Ser/Thr kinases collectively control the expression of ~30% of Mtb genes. Here, we will test a new and extensive regulatory connection between the Ser/Thr kinases and the His kinases of the TCSs and test the role of O-phosphorylation on the regulation of transcription factors. As a result of our exhaustive analysis of Mtb phosphorylation, we also obtained the first evidence of Arg phosphorylation in Mtb- the first bacterial Arg phosphoproteome outside of gram-positive bacteria. We will identify the relevant phosphoenzymes and test the idea that pArg functions as a degradation tag for ClpP- mediated proteolysis.
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