Cloning and Sequencing of Alginate Lyase Genes from Deep-Sea Strains of Vibrio and Agarivorans and Characterization of a New Vibrio Enzyme |
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Authors: | Kohsuke Uchimura Masayuki Miyazaki Yuichi Nogi Tohru Kobayashi Koki Horikoshi |
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Institution: | (1) Institute of Biogeoscience, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka Japan, 237-0061; |
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Abstract: | Four alginate lyase genes were cloned and sequenced from the genomic DNAs of deep-sea bacteria, namely members of Vibrio and Agarivorans. Three of them were from Vibrio sp. JAM-A9m, which encoded alginate lyases, A9mT, A9mC, and A9mL. A9mT was composed of 286 amino acids and 57% homologous
to AlxM of Photobacterium sp. A9mC (221 amino acids) and A9mL (522 amino acids) had the highest degree of similarity to two individual alginate lyases
of Vibrio splendidus with 74% and 84% identity, respectively. The other gene for alginate lyase, A1mU, was shotgun cloned from Agarivorans sp. JAM-A1m. A1mU (286 amino acids) showed the highest homology to AlyVOA of Vibrio sp. with 76% identity. All alginate lyases belong to polysaccharide lyase family 7, although, they do not show significant
similarity to one another with 14% to 58% identity. Among the above lyases, the recombinant A9mT was purified to homogeneity
and characterized. The molecular mass of A9mT was around 28 kDa. The enzyme was remarkably salt activated and showed the highest
thermal stability in the presence of NaCl. A9mT favorably degraded mannuronate polymer in alginate. We discussed substrate
specificities of family 7 alginate lyases based on their conserved amino acid sequences. |
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