2x9k
From Proteopedia
Structure of a E.coli porin
Structural highlights
FunctionOMPG_ECOLI Forms channels functionally larger than those of classical porins.[1] May act as a regulator of the RCS-phosphorelay signal transduction pathway.[2] Publication Abstract from PubMedThe channel activity of the outer-membrane protein G (OmpG) from Escherichia coli is pH-dependent. To investigate the role of the histidine pair His231/His261 in triggering channel opening and closing, we mutated both histidines to alanines and cysteines. Fourier transform infrared spectra revealed that the OmpG mutants stay-independent of pH-in an open conformation. Temperature ramp experiments indicate that the mutants are as stable as the open state of wild-type OmpG. The X-ray structure of the alanine-substituted OmpG mutant obtained at pH 6.5 confirms the constitutively open conformation. Compared to previous structures of the wild-type protein in the open and closed conformation, the mutant structure shows a difference in the extracellular loop L6 connecting beta-strands S12 and S13. A deletion of amino acids 220-228, which are thought to block the channel at low pH in wild-type OmpG, indicates conformational changes, which might be triggered by His231/His261. Correlation between the OmpG secondary structure and its pH-dependent alterations monitored by FTIR.,Korkmaz-Ozkan F, Koster S, Kuhlbrandt W, Mantele W, Yildiz O J Mol Biol. 2010 Aug 6;401(1):56-67. Epub 2010 Jun 16. PMID:20561532[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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