The importance of the Abn2 calcium cluster in the endo-1,5-arabinanase activity from Bacillus subtilis

作者：McVey C E; Ferreira M J; Correia B; Lahiri S; de Sanctis D; Carrondo Maria Armenia^*; Lindley P F; Nogueira Isabel de Sa; Soares Claudio Manuel; Bento Isabel

来源：Journal of Biological Inorganic Chemistry, 2014, 19(4-5): 505-513.

DOI：10.1007/s00775-014-1105-x

• Endo-alpha-L-arabinanase
• Catalytic mechanism
• X-ray crystallography
• Glycosyl hydrolase family 43
• Simulations of equilibrium protonation
• Site-directed mutagenesis

Arabinanase is a glycosyl hydrolase that is able to cleave the glycosidic bonds of alpha-1,5-l-arabinan, releasing arabino-oligosaccharides and l-arabinose. The enzyme has two domains, an N-terminal catalytic domain with a characteristic beta-propeller fold and a C-terminal domain whose function is unknown. A calcium ion, located near the catalytic site, serves to stabilize the N-terminal domain, but it has also been proposed to play a key role in the enzyme mechanism. The present work describes the structure of an inactive mutant of the wild-type enzyme (H318Q) and in which the calcium ion has been adventitiously replaced by nickel. These structural studies, together with functional and modelling studies, clearly support the role of the calcium ion in the overall reaction mechanism.

• 出版日期2014-6