Abstract
We have previously reported that the chitin catabolic cascade in Vibrio furnissii involves multiple signal transducing systems, and that mono- and disaccharide chemoreceptors/transporters are essential components of some of these systems. This and the accompanying papers (Bouma, C. L., and Roseman, S. (1996) J. Biol. Chem 271, 33457-33467; Keyhani, N. O., Wang, L.-X., Lee, Y. C., and Roseman, S. (1996) J. Biol. Chem. 271, 33409-33413) describe some of the sugar transporters. A 13-kilobase pair fragment of V. furnissii DNA was found to impart a Glc+, Man+ phenotype to Escherichia coli ptsG ptsM mutants, and encodes the mannose transporter, ptsM, of the phosphoenolpyruvate:glycose phosphotransferase system. Unlike the E. coli mannose permease, V. furnissii IIMan is inactive with GlcNAc and Fru, and is encoded by four genes rather than three. The gene order is manXYZW, where the product of manY corresponds to IIPMan, manZ to the mannose receptor IIBMan, and manX and manW to the single E. coli gene, manX (which encodes IIIMan, viz. IIAMan). Thus, in V. furnissii, the E. coli manX equivalent comprises two genes, which are separated in the genome by two other genes of the ptsM complex. Two additional open reading frames were detected in the V. furnissii DNA fragment. One encodes a GlcNAc-6-P deacetylase, and the other is similar to aldolase.
Highlights
We have previously reported that the chitin catabolic cascade in Vibrio furnissii involves multiple signal transducing systems, and that mono- and disaccharide chemoreceptors/transporters are essential components of some of these systems
We report here that V. furnissii ptsM differs from its E. coli homolog in the number of polypeptides required for its function, the gene order, and in its substrate specificity
Restriction fragments of the plasmid p3H1 were subcloned to determine the minimum size of V. furnissii DNA that would complement the GlcϪ defect in E. coli SR423, and a 5.1-kb SalI fragment met this requirement
Summary
We have previously reported that the chitin catabolic cascade in Vibrio furnissii involves multiple signal transducing systems, and that mono- and disaccharide chemoreceptors/transporters are essential components of some of these systems. A 13kilobase pair fragment of V. furnissii DNA was found to impart a Glc؉, Man؉ phenotype to Escherichia coli ptsG ptsM mutants, and encodes the mannose transporter, ptsM, of the phosphoenolpyruvate:glycose phosphotransferase system. Unlike the E. coli mannose permease, V. furnissii IIMan is inactive with GlcNAc and Fru, and is encoded by four genes rather than three. We report here that V. furnissii ptsM differs from its E. coli homolog in the number of polypeptides required for its function, the gene order, and in its substrate specificity
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