Publications

• Sequence of the gat operon for galactitol utilization from a wild-type strain EC3132 of Escherichia coli.

  Nobelmann B., Lengeler J.W.

  The sequence of the gat operon for galactitol (Gat) utilization from a wild-type isolate of Escherichia coli, strain EC3132, is presented. The operon comprises 7 open reading frames (ORFs) called gatYZABCDR. The genes are transcribed from a promoter located upstream of gatY. Genes gatABC encode th ... >> More

  The sequence of the gat operon for galactitol (Gat) utilization from a wild-type isolate of Escherichia coli, strain EC3132, is presented. The operon comprises 7 open reading frames (ORFs) called gatYZABCDR. The genes are transcribed from a promoter located upstream of gatY. Genes gatABC encode the substrate-specific domains IIA, IIB and IIC of a galactitol-specific Enzyme II (EIIGat) of the phospho enol pyruvate-dependent carbohydrate:phosphotransferase system (PTS); gatD encodes an NAD-dependent Gat 1-phosphate dehydrogenase; and gatY an enzyme which hydrolyses tagatose 1,6-bisphosphate; gene gatZ is required in a cell to show a Gat+ phenotype, but its physiological function has not yet been identified; gatR encodes a repressor for the gat operon. All genes are highly similar to the gat genes from E. coli K-12; in this organism they map at 46.70 min of the gene map, equivalent to about 2180-2186 kbp. << Less

  Biochim. Biophys. Acta 1262:69-72(1995) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Molecular analysis of the gat genes from Escherichia coli and of their roles in galactitol transport and metabolism.

  Nobelmann B., Lengeler J.W.

  In enteric bacteria, the hexitol galactitol (Gat) (formerly dulcitol) is taken up through enzyme II (II(Gat)) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS), and accumulated as galactitol 1-phosphate (Gat1P). The gat genes involved in galactitol metabolism have been isolated ... >> More

  In enteric bacteria, the hexitol galactitol (Gat) (formerly dulcitol) is taken up through enzyme II (II(Gat)) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS), and accumulated as galactitol 1-phosphate (Gat1P). The gat genes involved in galactitol metabolism have been isolated from the wild-type isolate Escherichia coli EC3132 and cloned on a 7.8-kbp PstI DNA fragment. They comprise six complete open reading frames and one truncated open reading frame in the order gatYZABCDR'. The genes gatABC code for the proteins GatA (150 residues) and GatB (94 residues), which correspond to the hydrophilic domains IIA(Gat) and IIB(Gat), and GatC, which represents a membrane-bound transporter domain IIC(Gat) (35 kDa, 427 residues). The three polypeptides together constitute a II(Gat) of average size (671 residues). Gene gatD codes for a Gat1P-specific NAD-dependent dehydrogenase (38 kDa, 346 residues), gatZ codes for a protein (42 kDa, 378 residues) of unknown function, and gatY (31 kDa, 286 residues) codes for a D-tagatose-1,6-bisphosphate aldolase with similarity to other known ketose-bisphosphate aldolases. The truncated gatR' gene, whose product shows similarity to the glucitol repressor GutR, closely resembles a gatR gene fragment from E. coli K-12. The gat genes map in both organisms at similar positions, in E. coli K-12, where they are transcribed counterclockwise at precisely 46.7 min or 2,173 to 2,180 kbp. The genes are expressed constitutively in both strains, probably due to a mutation(s) in gatR. Transcription initiation sites for the gatYp and the gatRp promoters were determined by primer extension analysis. << Less

  J. Bacteriol. 178:6790-6795(1996) [PubMed] [EuropePMC]

• Nature and properties of hexitol transport systems in Escherichia coli.

  Lengeler J.

  In Escherichia coli K-12 the naturally occurring hexitols D-mannitol, D-glucitol, and galactitol are taken up and phosphorylated via three distinct transport systems by a mechanism called either group translocation or vectorial phosphorylation. For every system, a membrane-bound enzyme II-complex ... >> More

  In Escherichia coli K-12 the naturally occurring hexitols D-mannitol, D-glucitol, and galactitol are taken up and phosphorylated via three distinct transport systems by a mechanism called either group translocation or vectorial phosphorylation. For every system, a membrane-bound enzyme II-complex of the phosphoenolpyruvate-dependent phosphotransferase system has been found, each requiring phosphoenolpyruvate, enzyme I, and HPr or alternatively P-HPr as the phosphate donor. Cells with a constitutive synthesis of all hexitol transport systems but with low P-HPr levels have very low transport and phosphorylating activities in vivo, although 40 to 90% of the enzyme II-complex activities are detected in cell extracts of such mutants. No indications for additional hexitol transport systems, especially for systems able to transport and accumulate free hexitols as in Klebsiella aerogenes, have been found. Substrate Km, and Vmax of the three transport systems for several hexitols and hexitol analogues have been determined by growth rates, transport activities, and in vitro phosphorylating activities. Each system was found to take up several hexitols, but only one hexitol serves as the inducer. This inducer invariably is the substrate with the highest affinity. Since bacterial transport systems, as a general rule, seem to have a relatively broad substrate specificity, in contrast to a more restricted inducer specificity, we propose to name the system inducible by D-mannitol and coded by the gene mtlA the D-mannitol transport system, the system inducible by D-glucitol and coded by gutA the D-glucitol transport system, and the system inducible by galactitol and coded by gatA the galactitol transport system. << Less

  J. Bacteriol. 124:39-47(1975) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.