4xwj
From Proteopedia
Histidine-containing phosphocarrier protein (HPr) and antisigma factor Rsd complex
Structural highlights
Function[RSD_ECOLI] Binds RpoD and negatively regulates RpoD-mediated transcription activation by preventing the interaction between the primary sigma factor RpoD with the catalytic core of the RNA polymerase and with promoter DNA. May be involved in replacement of the RNA polymerase sigma subunit from RpoD to RpoS during the transition from exponential growth to the stationary phase.[1] [2] [PTHP_ECOLI] General (non sugar-specific) component of the phosphoenolpyruvate-dependent sugar phosphotransferase system (sugar PTS). This major carbohydrate active-transport system catalyzes the phosphorylation of incoming sugar substrates concomitantly with their translocation across the cell membrane. The phosphoryl group from phosphoenolpyruvate (PEP) is transferred to the phosphoryl carrier protein HPr by enzyme I. Phospho-HPr then transfers it to the permease (enzymes II/III). Publication Abstract from PubMedHistidine-containing phosphocarrier protein (HPr) is a general component of the bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) involved in the phosphorylation-coupled transport of numerous sugars called PTS sugars. HPr mainly exists in a dephosphorylated form in the presence of PTS sugars in the medium, while its phosphorylation increases in the absence of PTS sugars. A recent study revealed that the dephosphorylated form of HPr binds and antagonizes the function of the antisigma factor Rsd. This anti-sigma factor sequesters the housekeeping sigma factor sigma(70) to facilitate switching of the sigma subunit on RNA polymerase from sigma(70) to the stress-responsive sigma factor sigma(S) in stationary-phase cells. In this study, the structure of the complex of Rsd and HPr was determined at 2.1 A resolution and revealed that the binding site for HPr on the surface of Rsd partly overlaps with that for sigma(70). The localization of the phosphorylation site on HPr at the binding interface for Rsd explains why phosphorylation of HPr abolishes its binding to Rsd. The mutation of crucial residues involved in the HPr-Rsd interaction significantly influenced the competition between HPr and sigma(70) for binding to Rsd both in vitro and in vivo. The results provide a structural basis for the linkage of global gene regulation to nutrient availability in the external environment. Structural basis for the sequestration of the anti-sigma(70) factor Rsd from sigma(70) by the histidine-containing phosphocarrier protein HPr.,Park YH, Um SH, Song S, Seok YJ, Ha NC Acta Crystallogr D Biol Crystallogr. 2015 Oct;71(Pt 10):1998-2008. doi:, 10.1107/S1399004715013759. Epub 2015 Sep 26. PMID:26457424[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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