1ajk

File:1ajk.gif

spinqualitylabelsall models 1ajk, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CIRCULARLY PERMUTED (1-3,1-4)-BETA-D-GLUCAN 4-GLUCANOHYDROLASE CPA16M-84

OverviewOverview

The 1,3-1,4-beta-glucanases from Bacillus macerans and Bacillus, licheniformis, as well as related hybrid enzymes, are stable proteins, comprised of one compact jellyroll domain. Their structures are studied in, an effort to reveal the degree of redundancy to which the, three-dimensional structure of protein domains is encoded by the amino, acid sequence. For the hybrid 1,3-1,4-beta-glucanase H(A16-M), it could be, shown recently that a circular permutation of the sequence giving rise to, the variant cpA16M-59 is compatible with wildtype-like enzymatic activity, and tertiary structure (Hahn et al., Proc. Natl. Acad. Sci. USA, 91:10417-10421, 1994). Since the circular permutation yielding cpA16M-59, mimicks that found in the homologous enzyme from Fibrobacter succinogenes, the question arose whether de novo circular permutations, not guided by, molecular evolution of the 1,3-1,4-beta-glucanases, could also produce, proteins with native-like fold. The circularly permuted variants, cpA16M-84, cpA16M-127, and cpA16M-154 were generated by PCR mutagenesis of, the gene encoding H(A16-M), synthesized in Escherichia coli and shown to, be active in beta-glucan hydrolysis. CpA16M-84 and cpA16M-127 were, crystallized in space groups P2(1) and P1, respectively, and their crystal, structures were determined at 1.80 and 2.07 A resolution. In both proteins, the main parts of the beta-sheet structure remain unaffected by the, circular permutation as is evident from a root-mean-square deviation of, main chain atoms from the reference structure within the experimental, error. The only major structural perturbation occurs near the novel chain, termini in a surface loop of cpA16M-84, which becomes destabilized and, rearranged. The results of this study are interpreted to show that: (1), several circular permutations in the compact jellyroll domain of the, 1,3-1,4-beta-glucanases are tolerated without radical change of enzymatic, activity or tertiary structure, (2) the three-dimensional structures of, simple domains are encoded by the amino acid sequence with sufficient, redundancy to tolerate a change in the sequential order of secondary, structure elements along the sequence, and (3) the native N-terminal, region is not needed to guide the folding polypeptide chain toward its, native conformation.

About this StructureAbout this Structure

1AJK is a Single protein structure of sequence from Paenibacillus macerans with CA, PO4 and EPE as ligands. Active as Licheninase, with EC number 3.2.1.73 Structure known Active Sites: CAA and CAB. Full crystallographic information is available from OCA.

ReferenceReference

Crystal structures and properties of de novo circularly permuted 1,3-1,4-beta-glucanases., Ay J, Hahn M, Decanniere K, Piotukh K, Borriss R, Heinemann U, Proteins. 1998 Feb 1;30(2):155-67. PMID:9489923

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