Dataset Information

Discovery and characterization of a distinctive exo-1,3/1,4-{beta}-glucanase from the marine bacterium Pseudoalteromonas sp. strain BB1.

ABSTRACT: Marine bacteria residing on local red, green, and brown seaweeds were screened for exo-1,3-?-glucanase (ExoP) activity. Of the 90 bacterial species isolated from 32 seaweeds, only one, a Pseudoalteromonas sp., was found to display such activity. It was isolated from a Durvillaea sp., a brown kelp known to contain significant amounts of the storage polysaccharide laminarin (1,3-?-D-glucan with some 1,6-? branching). Four chromatographic steps were utilized to purify the enzyme (ExoP). Chymotryptic digestion provided peptide sequences for primer design and subsequent gene cloning. The exoP gene coded for 840 amino acids and was located just 50 bp downstream from a putative lichenase (endo-1,3-1,4-?-glucanase) gene, suggesting possible cotranscription of these genes. Sequence comparisons revealed ExoP to be clustered within a group of bacterial glycosidases with high similarity to a group of glycoside hydrolase (GH3) plant enzymes, of which the barley exo-1,3/1,4-?-glucanase (ExoI) is the best characterized. The major difference between the bacterial and plant proteins is an extra 200- to 220-amino-acid extension at the C terminus of the former. This additional sequence does not correlate with any known functional domain, but ExoP was not active against laminarin when this region was removed. Production of recombinant ExoP allowed substrate specificity studies to be performed. The enzyme was found to possess similar levels of exoglucanase activity against both 1,4-? linkages and 1,3-? linkages, and so ExoP is designated an exo-1,3/1,4-?-exoglucanase, the first such bacterial enzyme to be characterized. This broader specificity could allow the enzyme to assist in digesting both cell wall cellulose and cytoplasmic laminarin.

SUBMITTER: Nakatani Y

PROVIDER: S-EPMC2953027 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

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Discovery and characterization of a distinctive exo-1,3/1,4-{beta}-glucanase from the marine bacterium Pseudoalteromonas sp. strain BB1.

Nakatani Yoshio Y Lamont Iain L IL Cutfield John F JF

Applied and environmental microbiology 20100820 20

Marine bacteria residing on local red, green, and brown seaweeds were screened for exo-1,3-β-glucanase (ExoP) activity. Of the 90 bacterial species isolated from 32 seaweeds, only one, a Pseudoalteromonas sp., was found to display such activity. It was isolated from a Durvillaea sp., a brown kelp known to contain significant amounts of the storage polysaccharide laminarin (1,3-β-D-glucan with some 1,6-β branching). Four chromatographic steps were utilized to purify the enzyme (ExoP). Chymotrypti ...[more]

PMID: 20729316

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Project description:The Pseudoalteromonas genus marine bacteria have attracted increasing interest because of their abilities to produce bioactive metabolites. The pigmented Pseudoalteromonas group encodes more secondary metabolite biosynthetic gene clusters (BGCs) than the non-pigmented group. Here, we report a yellow pigmented bacterium Pseudoalteromonas sp. strain T1lg65, which was isolated from a mangrove forest sediment. We showed that the yellow pigments of T1lg65 belong to the group of lipopeptide alterochromides. Further genetic analyses of the alterochromide BGC revealed that the yellow pigments are biosynthesized by aryl-polyene synthases and nonribosomal peptide synthases. Within the gene cluster, altA encodes a tyrosine ammonia acid lyase, which catalyzes synthesis of the precursor 4-hydroxycinnamic acid (4-HCA) from tyrosine in the alterochromide biosynthetic pathway. In addition, altN, encoding a putative flavin-dependent halogenase, was proven to be responsible for the bromination of alterochromides based on gene deletion, molecular docking, and site mutagenesis analyses. In summary, the biosynthetic pathway, precursor synthesis, and bromination mechanism of the lipopeptide alterochromides were studied in-depth. Our results expand the knowledge on biosynthesis of Pseudoalteromonas pigments and could promote the development of active pigments in the future.IMPORTANCEThe marine bacteria Pseudoalteromonas spp. are important biological resources because they are producers of bioactive natural products, including antibiotics, pigments, enzymes, and antimicrobial peptides. One group of the microbial pigments, alterochromides, holds a great value for their novel lipopeptide structures and antimicrobial activities. Previous studies were limited to the structural characterization of alterochromides and genome mining for the alterochromide biosynthesis. This work focused on the biosynthetic mechanism for alterochromide production, especially revealing functions of two key genes within the gene cluster for the alterochromide biosynthesis. On the one hand, our study provides a target for metabolic engineering of the alterochromide biosynthesis; on the other hand, the 4-HCA synthase AltA and brominase AltN show potential in the biocatalyst industry.

Dataset Information

Discovery and characterization of a distinctive exo-1,3/1,4-{beta}-glucanase from the marine bacterium Pseudoalteromonas sp. strain BB1.

Publications

Discovery and characterization of a distinctive exo-1,3/1,4-{beta}-glucanase from the marine bacterium Pseudoalteromonas sp. strain BB1.

Similar Datasets

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