Abstract
Several strains of the genus Sphingomonas produce sphingans, extracellular polysaccharides used as thickeners, emulsifiers and gelling agents. The pgmG gene from Sphingomonas sanxanigenens, which encodes a bifunctional protein with phosphoglucomutase and phosphomannomutase activities, was cloned and sequenced. The predicted amino acid sequence of the PgmG protein possessed 460 amino acids and a calculated molecular mass of 49.8 kDa, and it was 80 % identical to PGM/PMM from S. elodea. We overexpressed pgmG in Escherichia coli, and the purified protein displayed a K m of 0.2 mM and a V max of 1.3 μmol min(-1) mg(-1) with glucose 1-phosphate as substrate. The catalytic efficiency (K cat/K m) of PgmG was about 15-fold higher for glucose 1-phosphate than for mannose 1-phosphate. Overexpression of pgmG in S. sanxanigenens resulted in a 17 ± 0.3 % increase in sphingan production to ~12.5 g l(-1).
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cloning, Molecular
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DNA, Bacterial / chemistry
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DNA, Bacterial / genetics
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Escherichia coli / genetics
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Gene Expression
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Kinetics
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Molecular Sequence Data
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Molecular Weight
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Phosphoglucomutase / chemistry
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Phosphoglucomutase / genetics*
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Phosphoglucomutase / isolation & purification
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Phosphoglucomutase / metabolism*
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Phosphotransferases (Phosphomutases) / chemistry
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Phosphotransferases (Phosphomutases) / genetics*
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Phosphotransferases (Phosphomutases) / isolation & purification
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Phosphotransferases (Phosphomutases) / metabolism*
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Polysaccharides, Bacterial / metabolism
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Sequence Analysis, DNA
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Sphingomonas / enzymology*
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Sphingomonas / metabolism
Substances
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DNA, Bacterial
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Polysaccharides, Bacterial
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Recombinant Proteins
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sphingan
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Phosphotransferases (Phosphomutases)
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Phosphoglucomutase
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phosphomannomutase