4K6H

Crystal structure of CALB mutant L278M from Candida antarctica

Summary for 4K6H

• Entry DOI: 10.2210/pdb4k6h/pdb
• Related: 4K5Q 4K6G 4K6K
• Descriptor: Lipase B, 1,2-ETHANEDIOL (3 entities in total)
• Functional Keywords: lipase, hydrolase
• Biological source: Candida antarctica (Yeast)
• Total number of polymer chains: 2
• Total formula weight: 68835.47

Authors

An, J.,Xie, Y.,Feng, Y.,Wu, G. (deposition date: 2013-04-15, release date: 2014-01-29, Last modification date: 2024-10-30)

Primary citation

Xie, Y.,An, J.,Yang, G.,Wu, G.,Zhang, Y.,Cui, L.,Feng, Y.
Enhanced enzyme kinetic stability by increasing rigidity within the active site.
J.Biol.Chem., 289:7994-8006, 2014

PubMed Abstract: Enzyme stability is an important issue for protein engineers. Understanding how rigidity in the active site affects protein kinetic stability will provide new insight into enzyme stabilization. In this study, we demonstrated enhanced kinetic stability of Candida antarctica lipase B (CalB) by mutating the structurally flexible residues within the active site. Six residues within 10 Å of the catalytic Ser(105) residue with a high B factor were selected for iterative saturation mutagenesis. After screening 2200 colonies, we obtained the D223G/L278M mutant, which exhibited a 13-fold increase in half-life at 48 °C and a 12 °C higher T50(15), the temperature at which enzyme activity is reduced to 50% after a 15-min heat treatment. Further characterization showed that global unfolding resistance against both thermal and chemical denaturation also improved. Analysis of the crystal structures of wild-type CalB and the D223G/L278M mutant revealed that the latter formed an extra main chain hydrogen bond network with seven structurally coupled residues within the flexible α10 helix that are primarily involved in forming the active site. Further investigation of the relative B factor profile and molecular dynamics simulation confirmed that the enhanced rigidity decreased fluctuation of the active site residues at high temperature. These results indicate that enhancing the rigidity of the flexible segment within the active site may provide an efficient method for improving enzyme kinetic stability.

PubMed: 24448805
DOI: 10.1074/jbc.M113.536045

Experimental method

X-RAY DIFFRACTION (1.6 Å)