Molecular cloning of the gene encoding an outer-membrane-associated beta-N-acetylglucosaminidase involved in chitin degradation system of Alteromonassp strain O-7

The gene encoding beta -N-acetylglucosaminidase (GlcNAcaseA) was cloned usi ng PCR with degenerate oligonucleotide primers from the partial amino acid sequence of the enzyme. The gene encoded a polypeptide of 863 amino acids w ith a predicted molecular mass of 97 kDa. A characteristic signal peptide, which was present at the amino-terminus of the precursor protein, contained four amino acids (Ala-Gly-Cys-Ser) identical in sequence and location to t he processing and modification sites of the outer membrane lipoprotein of E scherichia coli, indicating that the mature GlcNAcaseA is a lipoprotein the N-terminal cysteine residue of which would be modified by the fatty acid t hat anchors the protein in the membrane. The predicted amino acid sequence of GlcNAcaseA showed similarity to bacterial beta -N-acetylglucosaminidases belonging to the family 20 glycosyl hydrolases.