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Molecular insights into the mechanism of thermal stability of actinomycete mannanase
Author(s) -
Kumagai Yuya,
Uraji Misugi,
Wan Kun,
Okuyama Masayuki,
Kimura Atsuo,
Hatanaka Tadashi
Publication year - 2016
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.12322
Subject(s) - subfamily , thermal stability , chemistry , hydrolysis , glycoside hydrolase , mutant , hydrogen bond , hydrolase , binding site , biochemistry , stereochemistry , enzyme , function (biology) , biophysics , crystallography , biology , organic chemistry , molecule , genetics , gene
Streptomyces thermolilacinus mannanase (StMan), which requires Ca 2+ for its enhanced thermal stability and hydrolysis activity, possesses two Ca 2+ ‐binding sites in loop6 and loop7. We evaluated the function of the Ca 2+ ‐binding site in loop7 and the hydrogen bond between residues Ser247 in loop6 and Asp279 in loop7. The Ca 2+ ‐binding in loop7 was involved only in thermal stability. Mutations of Ser247 or Asp279 retained the Ca 2+ ‐binding ability; however, mutants showed less thermal stability than StMan. Phylogenetic analysis indicated that most glycoside hydrolase family 5 subfamily 8 mannanases could be stabilized by Ca 2+ ; however, the mechanism of StMan thermal stability was found to be quite specific in some actinomycete mannanases.