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Publication Abstract from PubMed

The histidine brace (His-brace) is a copper-binding motif that is associated with both oxidative enzymes and proteinaceous copper chaperones. Here, we used biochemical and structural methods to characterize mutants of a His-brace-containing copper chaperone from Pseudomonas fluorescens (PfCopC). A total of 15 amino acid variants in primary and second-sphere residues were produced and characterized in terms of their copper binding and redox properties. PfCopC has a very high affinity for Cu(II) and also binds Cu(I). A high reorganization barrier likely prevents redox cycling and, thus, catalysis. In contrast, mutations in the conserved second-sphere Glu27 enable slow oxidation of ascorbate. The crystal structure of the variant E27A confirmed copper binding at the His-brace. Unexpectedly, Asp83 at the equatorial position was shown to be indispensable for Cu(II) binding in the His-brace of PfCopC. A PfCopC mutant that was designed to mimic the His-brace from lytic polysaccharide monooxygenase-like family X325 did not bind Cu(II), but was still able to bind Cu(I). These results highlight the importance of the proteinaceous environment around the copper His-brace for reactivity and, thus, the difference between enzyme and chaperone.

Copper binding and reactivity at the histidine brace motif: insights from mutational analysis of the Pseudomonas fluorescens copper chaperone CopC.,Ipsen JO, Hernandez-Rollan C, Muderspach SJ, Brander S, Bertelsen AB, Jensen PE, Norholm MHH, Lo Leggio L, Johansen KS FEBS Lett. 2021 Jun;595(12):1708-1720. doi: 10.1002/1873-3468.14092. Epub 2021, May 14. PMID:33896006^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.