3tpd
From Proteopedia
Structure of pHipA, monoclinic form
Structural highlights
Function[HIPA_ECOLI] Toxic component of a toxin-antitoxin (TA) module. Autophosphorylates (Ser-150) and phosphorylates EF-Tu in vitro (on 'Thr-383'), may act on other proteins as well. The hipA7 mutation leads to increased generation of persister cells, cells that survive antibiotic treatment probably by entering into a dormant state. Wild-type cells produce persisters at a frequency of 10-6 to 10-5 whereas mutant hipA7 cells produce persisters at a frequency of 10-2. Generation of persister cells requires (p)ppGpp as cells lacking relA or relA/spoT generate fewer or no persister cells respectively compared to hipA7. Low level expression of HipA causes cell filamentation and depending on the protein level is toxic enough to reduce cell growth or even kill cells. Expression of wild-type HipA also leads to high antibiotic tolerance of the survivor cells. The toxic effect of HipA is neutralized by its cognate antitoxin HipB. With HipB acts as a corepressor for transcription of the hipBA promoter.[1] [2] [3] [4] [5] Publication Abstract from PubMedHipA is a bacterial serine/threonine protein kinase that phosphorylates targets, bringing about persistence and multidrug tolerance. Autophosphorylation of residue Ser150 is a critical regulatory mechanism of HipA function. Intriguingly, Ser150 is not located on the activation loop, as are other kinases; instead, it is in the protein core, where it forms part of the ATP-binding "P loop motif." How this buried residue is phosphorylated and regulates kinase activity is unclear. Here, we report multiple structures that reveal the P loop motif's exhibition of a remarkable "in-out" conformational equilibrium, which allows access to Ser150 and its intermolecular autophosphorylation. Phosphorylated Ser150 stabilizes the "out state," which inactivates the kinase by disrupting the ATP-binding pocket. Thus, our data reveal a mechanism of protein kinase regulation that is vital for multidrug tolerance and persistence, as kinase inactivation provides the critical first step in allowing dormant cells to revert to the growth phenotype and to reinfect the host. Role of Unusual P Loop Ejection and Autophosphorylation in HipA-Mediated Persistence and Multidrug Tolerance.,Schumacher MA, Min J, Link TM, Guan Z, Xu W, Ahn YH, Soderblom EJ, Kurie JM, Evdokimov A, Moseley MA, Lewis K, Brennan RG Cell Rep. 2012 Sep 27;2(3):518-25. doi: 10.1016/j.celrep.2012.08.013. Epub 2012, Sep 20. PMID:22999936[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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