Nucleotide sequence of the <i>ugp genes of Escherichia coli</i> K‐12: homology to the maltose system

Overduin, Piet; Boos, Winfried; Tommassen, Jan

doi:10.1111/j.1365-2958.1988.tb00088.x

Cited by 100 publications

(68 citation statements)

References 40 publications

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“…The highly conserved lysine residue (K) is in boldface, and the amino acid residues of AmyE of T. thermosulfurigenes EM1 that match the signature sequence are boxed. Tt, T. thermosulfurigenes EM1 (this report); Ec., E. coli (11,31) In accordance with the results of the Northern blot experiments, two putative transcription start sites of the amyBEDC operon (Fig. 4) and one start site upstream of the monocistronic amyA operon (data not shown) were determined by primer extension analysis.…”

Section: Resultsmentioning

confidence: 51%

Molecular analysis of the amy gene locus of Thermoanaerobacterium thermosulfurigenes EM1 encoding starch-degrading enzymes and a binding protein-dependent maltose transport system

et al. 1996

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A gene of Thermoanaerobacterium thermosulfurigenes EM1 encoding a protein with similarity to the maltosebinding protein of Escherichia coli was cloned and sequenced. It was located in the amy gene region of the chromosome downstream of the pullulanase-encoding amyB gene and upstream of amyDC, encoding membrane components of an ABC transport system, and the ␣-amylase gene amyA. The gene was designated amyE. Analysis of mRNA by Northern (RNA) blotting revealed that expression of the amy gene region is repressed during growth on glucose. Maximum levels of mRNA were detected with maltose as a substrate. An operon which was transcribed in the order amyBEDC was identified. However, an additional transcription start point was found in front of amyE. The amyA gene represented a monocistronic operon. Putative ؊35 and ؊10 promoter sites were deduced from the three transcription start sites of the amy gene region, and possible regulatory regions mediating induction by maltose and catabolite repression by glucose were identified by sequence analysis and comparison. The biochemical characterization of maltose uptake in T. thermosulfurigenes EM1 revealed two transport systems with K m values of 7 M (high affinity) and 400 M (low affinity). We conclude that the high-affinity system, which is specific for maltose and maltotriose, is a binding-proteindependent transporter encoded by amyEDC. The gene for the putative ATP-binding protein has not yet been identified, and in contrast to similar systems in other bacteria, it is not located in the immediate vicinity of the chromosome.Starch-degrading enzymes from thermophilic microorganisms have been extensively studied in recent years. Several enzymes have been purified and characterized (21,26,37), and in many cases the corresponding genes have been cloned, analyzed, and expressed in Escherichia coli or Bacillus subtilis (2,7,24,27). On the other hand, regulation of gene expression and enzyme synthesis as well as transport of the soluble products of the depolymerases into the cell have received surprisingly little attention. It is clear that transport mechanisms are similar to those in other bacteria. To date, only a limited number of studies on carbohydrate transport in thermophiles have been published. A phosphotransferase system for glucose or cellobiose in thermophiles has not yet been found. Indirect evidence based on the effects of metabolic inhibitors and uncouplers on glucose transport in Clostridium thermocellum and C. thermohydrosulfuricum (now Thermoanaerobacter thermohydrosulfuricus) has suggested that transport is dependent on ATP rather than a proton or sodium gradient (15, 29). Recently, it has been proposed that glucose and xylose are taken up by Thermoanaerobacter thermohydrosulfuricus through a facilitated diffusion mechanism (8, 9). On the other hand, in C. thermosulfurogenes EM1 (now Thermoanaerobacterium thermosulfurigenes), two genes, amyC and amyD, which are homologous to two membrane components of the maltose and glycerol-3-phosphate transport systems of E. c...

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Section: Resultsmentioning

confidence: 51%

Molecular analysis of the amy gene locus of Thermoanaerobacterium thermosulfurigenes EM1 encoding starch-degrading enzymes and a binding protein-dependent maltose transport system

et al. 1996

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“…SMc02520 (glpD) encodes a glycerol-3-phosphate dehydrogenase. ABC-T SMb20416 has high identity to the glycerol-3-phosphate (UgpBAEC) system in E. coli (29) but was constitutively expressed, as measured by a plasmid fusion.…”

Section: Site the Results Are Shown In Full Inmentioning

confidence: 99%

Mapping the Sinorhizobium meliloti 1021 solute-binding protein-dependent transportome

Mauchline

Fowler

East

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

137

146

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The number of solute-binding protein-dependent transporters in rhizobia is dramatically increased compared with the majority of other bacteria so far sequenced. This increase may be due to the high affinity of solute-binding proteins for solutes, permitting the acquisition of a broad range of growth-limiting nutrients from soil and the rhizosphere. The transcriptional induction of these transporters was studied by creating a suite of plasmid and integrated fusions to nearly all ATP-binding cassette (ABC) and tripartite ATP-independent periplasmic (TRAP) transporters of Sinorhizobium meliloti. In total, specific inducers were identified for 76 transport systems, amounting to Ϸ47% of the ABC uptake systems and 53% of the TRAP transporters in S. meliloti. Of these transport systems, 64 are previously uncharacterized in Rhizobia and 24 were induced by solutes not known to be transported by ABC-or TRAP-uptake systems in any organism. This study provides a global expression map of one of the largest transporter families (transportome) and an invaluable tool to both understand their solute specificity and the relationships between members of large paralogous families.ATP-binding cassette ͉ expression ͉ high throughput ͉ transport ͉ tripartite ATP-independent periplasmic

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“…Do mammalian cells express Pdr5-like proteins that can modulate cellular responses to glucocorticoids? The distinct substrate selectivity of ABC transporters that display sequence similarities in their transmembrane regions (21,22) discouraged us from probing for Pdr5-like proteins on the basis of sequence homology. We therefore took a pharmacological approach and sought drugs that might affect the function of a mammalian steroid exporter.…”

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confidence: 99%

An FK506-sensitive Transporter Selectively Decreases Intracellular Levels and Potency of Steroid Hormones

Kralli

Yamamoto

1996

Journal of Biological Chemistry

121

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Steroid hormones bind and activate intracellular receptors that are ligand-regulated transcription factors. Mammalian steroid receptors can confer hormone-dependent transcriptional enhancement when expressed in yeast, thereby enabling the genetic identification of nonreceptor proteins that function in the hormone signal transduction pathway. Pdr5p (Lem1/Sts1/Ydr1p), a yeast ATP-binding cassette transporter, selectively decreases the intracellular levels of particular steroid hormones, indicating that active processes can affect the passage of steroids across biological membranes. In yeast, the immunosuppressive drug FK506 inhibited Pdr5p, thereby potentiating activation of the glucocorticoid receptor by dexamethasone, a ligand that is exported by Pdr5p. In mammalian L929 cells but not in HeLa cells, FK506 potentiated dexamethasone responsiveness and increased dexamethasone accumulation, without altering the hormone-binding properties of the glucocorticoid receptor. We suggest that an FK506-sensitive transporter in L929 cells selectively decreases intracellular hormone levels and, consequently, the potency of particular steroids. Thus, steroid transporters may modulate, in a cell-specific manner, an initial step in signaling, the availability of hormone to the receptor.Cells use intracellular receptors to sense and respond to extracellular signals such as steroid, thyroid, retinoid, and vitamin D hormones (1). Responses to these hormones can be modulated by other signals and by cellular context. For example, activators of kinases can potentiate or abrogate glucocorticoid action in a cell-type specific manner (2, 3). Resistance to glucocorticoids or mineralocorticoids in patients with wild-type receptors for these steroids further demonstrates that factors in addition to the receptors can determine hormone response (4 -7). One step at which response could be modulated is the availability of hormone to the intracellular receptors. The levels of hormone that can interact with and activate the receptors could be determined by proteins affecting hormone influx, efflux, or metabolism.The existence of proteins that actively affect the influx or efflux of steroid ligands has been controversial. Although steroids are small lipophilic molecules that can diffuse freely in lipid bilayers, corticosterone uptake into liver membrane vesicles is saturable and produces elevated hormone concentration inside the vesicles (8). Studies in yeast, where expression of the mammalian glucocorticoid receptor (GR) 1 supports hormonedependent transcriptional regulation of appropriate reporter constructs (9, 10), have revealed a yeast ATP-binding cassette (ABC) transporter, Pdr5p (Lem1/Sts1/Ydr1p), that decreases intracellular accumulation of particular steroids (11), and of other non-steroid drugs (12-14). The identification of a steroid exporter in yeast raised the possibility that similar transporters might modulate steroid potencies in mammalian cells. In support of this notion, L929 mouse fibroblasts have been reported to export cortisol...

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Nucleotide sequence of the ugp genes of Escherichia coli K‐12: homology to the maltose system

Cited by 100 publications

References 40 publications

Molecular analysis of the amy gene locus of Thermoanaerobacterium thermosulfurigenes EM1 encoding starch-degrading enzymes and a binding protein-dependent maltose transport system

Molecular analysis of the amy gene locus of Thermoanaerobacterium thermosulfurigenes EM1 encoding starch-degrading enzymes and a binding protein-dependent maltose transport system

Mapping the Sinorhizobium meliloti 1021 solute-binding protein-dependent transportome

An FK506-sensitive Transporter Selectively Decreases Intracellular Levels and Potency of Steroid Hormones

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