2h1b
ResA E80Q
Structural highlights
FunctionRESA_BACSU Thiol-disulfide oxidoreductase which is required in disulfide reduction during c-type cytochrome synthesis. May accept reducing equivalents from CcdA, leading to breakage of disulfide bonds in apocytochrome c; following this reduction heme can be covalently attached. Does not play a role in sporulation.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedResA, an extracytoplasmic thioredoxin from Bacillus subtilis, acts in cytochrome c maturation by reducing the disulfide bond present in apocytochromes prior to covalent attachment of heme. This reaction is (and has to be) specific, as broad substrate specificity would result in unproductive shortcircuiting with the general oxidizing thioredoxin(s) present in the same compartment. Using mutational analysis and subsequent biochemical and structural characterization of active site variants, we show that reduced ResA displays unusually low reactivity at neutral pH, consistent with the observed high pKa values>8 for both active site cysteines. Residue Glu80 is shown to play a key role in controlling the acid-base properties of the active site. A model in which substrate binding dramatically enhances the reactivity of the active site cysteines is proposed to account for the specificity of the protein. Such a substratemediated activation mechanism is likely to have wide relevance for extracytoplasmic thioredoxins. Molecular basis for specificity of the extracytoplasmic thioredoxin ResA.,Lewin A, Crow A, Oubrie A, Le Brun NE J Biol Chem. 2006 Nov 17;281(46):35467-77. Epub 2006 Sep 13. PMID:16971393[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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