Structural highlights
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 PubMedCircular permutation of Candida antarctica lipase B yields several enzyme variants with substantially increased catalytic activity. To better understand the structural and functional consequences of protein termini reorganization, we have applied protein engineering and x-ray crystallography to cp283, one of the most active hydrolase variants. Our initial investigation has focused on the role of an extended surface loop, created by linking the native N- and C-termini, on protein integrity. Incremental truncation of the loop partially compensates for observed losses in secondary structure and the permutants' temperature of unfolding. Unexpectedly, the improvements are accompanied by quaternary-structure changes from monomer to dimer. The crystal structures of one truncated variant (cp283 Delta 7) in the apo-form determined at 1.49 A resolution and with a bound phosphonate inhibitor at 1.69 A resolution confirmed the formation of a homodimer by swapping of the enzyme's 35-residue N-terminal region. Separately, the new protein termini at amino acid positions 282/283 convert the narrow access tunnel to the catalytic triad into a broad crevice for accelerated substrate entry and product exit while preserving the native active-site topology for optimal catalytic turnover. Structural redesign of lipase B from Candida antarctica by circular permutation and incremental truncation.,Qian Z, Horton JR, Cheng X, Lutz S J Mol Biol. 2009 Oct 16;393(1):191-201. Epub 2009 Aug 13. PMID:19683009[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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