2lhs

Structure of the chitin binding protein 21 (CBP21)

spinqualitylabelsall models 2lhs Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2lhs is a 1 chain structure with sequence from Serratia marcescens. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR, 20 models Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function LP10_SERMA Lytic polysaccharide monooxygenase (LPMO) that oxidatively cleaves alpha- and beta-chitin with C1 regioselectivity (PubMed:23112164). Catalysis by LPMOs requires the reduction of the active-site copper from Cu(II) to Cu(I) by a reducing agent and H(2)O(2) or O(2) as a cosubstrate (PubMed:23112164). Publication Abstract from PubMed Lytic polysaccharide monooxygenases currently classified as carbohydrate binding module family 33 (CBM33) and glycoside hydrolase family 61 (GH61) are likely to play important roles in future biorefining. However, the molecular basis of their unprecedented catalytic activity remains largely unknown. We have used NMR techniques and isothermal titration calorimetry to address structural and functional aspects of CBP21, a chitin-active CBM33. NMR structural and relaxation studies showed that CBP21 is a compact and rigid molecule, and the only exception is the catalytic metal binding site. NMR data further showed that His28 and His114 in the catalytic center bind a variety of divalent metal ions with a clear preference for Cu(2+) (K(d) = 55 nM; from isothermal titration calorimetry) and higher preference for Cu(1+) (K(d) approximately 1 nM; from the experimentally determined redox potential for CBP21-Cu(2+) of 275 mV using a thermodynamic cycle). Strong binding of Cu(1+) was also reflected in a reduction in the pK(a) values of the histidines by 3.6 and 2.2 pH units, respectively. Cyanide, a mimic of molecular oxygen, was found to bind to the metal ion only. These data support a model where copper is reduced on the enzyme by an externally provided electron and followed by oxygen binding and activation by internal electron transfer. Interactions of CBP21 with a crystalline substrate were mapped in a (2)H/(1)H exchange experiment, which showed that substrate binding involves an extended planar binding surface, including the metal binding site. Such a planar catalytic surface seems well-suited to interact with crystalline substrates. NMR structure of a lytic polysaccharide monooxygenase provides insight into copper binding, protein dynamics, and substrate interactions.,Aachmann FL, Sorlie M, Skjak-Braek G, Eijsink VG, Vaaje-Kolstad G Proc Natl Acad Sci U S A. 2012 Nov 13;109(46):18779-84. doi:, 10.1073/pnas.1208822109. Epub 2012 Oct 29. PMID:23112164 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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