Molecular identification of family 38 alpha-mannosidase of Bacillus sp. strain GL1, responsible for complete depolymerization of xanthan.
When cells of Bacillus sp. strain GL1 were grown in a medium containing xanthan as a carbon source, alpha-mannosidase exhibiting activity toward p-nitrophenyl-alpha-D-mannopyranoside (pNP-alpha-D-Man) was produced intracellularly. The 350-kDa alpha-mannosidase purified from a cell extract of the bacterium was a trimer comprising three identical subunits, each with a molecular mass of 110 kDa. The enzyme hydrolyzed pNP-alpha-D-Man (Km = 0.49 mM) and D-mannosyl-(alpha-1,3)-D-glucose most efficiently at pH 7.5 to 9.0, indicating that the enzyme catalyzes the last step of the xanthan depolymerization pathway of Bacillus sp. strain GL1. The gene for alpha-mannosidase cloned most by using N-terminal amino acid sequence information contained an open reading frame (3,144 bp) capable of coding for a polypeptide with a molecular weight of 119,239. The deduced amino acid sequence showed homology with the amino acid sequences of alpha-mannosidases belonging to glycoside hydrolase family 38.
Nankai
Hirokazu
H
Department of Basic and Applied Molecular Biotechnology, Division of Food and Biological Science, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan.
Hashimoto
Wataru
W
Murata
Kousaku
K
D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008361:Mannosidases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008670:Metals / Q000378:metabolism; D008970:Molecular Weight; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity; D013696:Temperature
D004269:DNA, Bacterial; D008670:Metals; D011135:Polysaccharides, Bacterial; D008361:Mannosidases; C002563:xanthan gum