Structure and function of yeast mannoprotein degrading enzymes

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To Clarify the structure of yeast mannoprotein degrading enzymes, at first, a gene (aman2) encoding 1, 2-α-D-mannosidase from Bacillus sp.M-90 was cloned. The putative aman2 was 5928 base pairs long and encoded a mature 1, 2-α-D-mannosidase protein of 1939 amino acids and a signal peptide of 37 amino acids. The deduced amino acid sequence exhibits no similarity to other 1, 2-α-D-mannosidases identified in various organisms. The recombinant protein was verified by immunoblotting with anti-1, 2-α-D-mannosidease antibodies and showed hydrolytic activity to 1, 2-α-D-mannobise and yeast mannan. Secondly, a gene (aman6) encoding endo-1, 6-α-mannanase, a yeast mannan backbone degrading enzyme from Bacilles circulans was cloned and the gene was expressed in Escherichis coli. The putative aman6 wa 1767 base pares long and encodes a mature 1, 6-α-mannanase protein of 589 amino acids and a signal peptide of 36 amino acids. The purified mature 1, 6-α-D-mannanase from E.coli transformant showed 61-kDa protein, and N-terminal amino acid sequense and other general properties of the recombinant enzyme were identical to those of 1, 6-α-D-mannanase from Bacillus circulans TN-31.A data base serch indicates both aman2 and aman6 were novel genes.