[31] Assay, genetics, proteins, and reconstitution of proton-linked galactose, arabinose, and xylose transport systems of Escherichia coli

Henderson, Peter J. F.; Macpherson, Andrew J.

doi:10.1016/s0076-6879(86)25033-8

Cited by 60 publications

(52 citation statements)

References 72 publications

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“…The uptake activity was profoundly affected by reaction pH and showed an optimum between pH 6 and 7 (Table 1). This is typical of a proton-linked energization mechanism (4,12,14).…”

Section: A Structural Model Of the Mhp Proteinmentioning

confidence: 86%

The Hydantoin Transport Protein from Microbacterium liquefaciens

Suzuki

Henderson

2006

J Bacteriol

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The gene hyuP from Microbacterium liquefaciens AJ 3912 with an added His 6 tag was cloned into the expression plasmid pTTQ18 in an Escherichia coli host strain. The transformed E. coli showed transport of radioisotope-labeled 5-substituted hydantoins with apparent K m values in the micromolar range. This activity exhibited a pH optimum of 6.6 and was inhibited by dinitrophenol, indicating the requirement of energy for the transport system. 5-Indolyl methyl hydantoin and 5-benzyl hydantoin were the preferred substrates, with selectivity for a hydrophobic substituent in position 5 of hydantoin and for the L isomer over the D isomer. Hydantoins with less hydrophobic substituents, cytosine, thiamine, uracil, allantoin, adenine, and guanine, were not effective ligands. The His-tagged hydantoin transport protein was located in the inner membrane fraction, from which it was solubilized and purified and its identity was authenticated.

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“…The uptake activity was profoundly affected by reaction pH and showed an optimum between pH 6 and 7 (Table 1). This is typical of a proton-linked energization mechanism (4,12,14).…”

Section: A Structural Model Of the Mhp Proteinmentioning

confidence: 86%

The Hydantoin Transport Protein from Microbacterium liquefaciens

Suzuki

Henderson

2006

J Bacteriol

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“…For maximal protection of sulfhydryl groups, substrate concentrations must be ‫ف‬ 10 to 20 times the K m value (Henderson and Macpherson, 1986). For the pGlcT, with a K m (Glc) of ‫ف‬ 20 mM, maximum protection requires Glc concentrations of 200 to 400 mM.…”

Section: Identification Of the Pglct By Differential Labeling With Nemmentioning

confidence: 99%

Identification, Purification, and Molecular Cloning of a Putative Plastidic Glucose Translocator

et al. 2000

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During photosynthesis, part of the fixed carbon is directed into the synthesis of transitory starch, which serves as an intermediate carbon storage facility in chloroplasts. This transitory starch is mobilized during the night. Increasing evidence indicates that the main route of starch breakdown proceeds by way of hydrolytic enzymes and results in glucose formation. This pathway requires a glucose translocator to mediate the export of glucose from the chloroplasts. We have reexamined the kinetic properties of the plastidic glucose translocator and, using a differential labeling procedure, have identified the glucose translocator as a component of the inner envelope membrane. Peptide sequence information derived from this protein was used to isolate cDNA clones encoding a putative plastidic glucose translocator from spinach, potato, tobacco, Arabidopsis, and maize. We also present the molecular characterization of a candidate for a hexose transporter of the plastid envelope membrane. This transporter, initially characterized more than 20 years ago, is closely related to the mammalian glucose transporter GLUT family and differs from all other plant hexose transporters that have been characterized to date. INTRODUCTIONIn plants, carbon fixed during the day is exported from the chloroplasts in the form of triose phosphate (trioseP), which is converted in the cytosol to sucrose. Sucrose often serves as the predominant photoassimilate being allocated to sink tissues. The export of trioseP from the chloroplasts is mediated by the trioseP/3-phosphoglycerate/phosphate translocator (TPT; Fliege et al., 1978; Flügge et al., 1989). Rather than being exported, a considerable amount of the fixed carbon is maintained within the chloroplasts and is involved in the biosynthesis of transitory starch, which could amount to approximately one-half of the carbon assimilated by photosynthesis during the day. During the next dark period, transitory starch is mobilized to sustain a continuous supply of carbon (i.e., sucrose) for export to growing sinks as well as for energy metabolism in leaves. Mutants lacking the ability to synthesize (Caspar et al., 1985; Hanson and McHale, 1988;Huber and Hanson, 1992; Geiger et al., 1995) or degrade transitory starch (Zeeman et al., 1998a(Zeeman et al., , 1998bCaspar et al., 1991) show reduced growth under conditions in which photosynthesis is restricted.Starch degradation could follow either the phosphorolytic pathway, yielding trioseP, or the amylolytic pathway, leading to free sugars, glucose (Glc), and maltose. There is evidence that the dominant pathway for the degradation of transitory starch is the amylolytic one. First, trioseP, the end product of the phosphorolytic pathway, must be exported from the chloroplasts and subsequently be converted to hexose phosphate (hexoseP) in the cytosol. This reaction is controlled by the regulatory metabolite fructose 2,6-bisphosphate, which is a strong inhibitor of the cytosolic fructosebisphosphate phosphatase (Stitt, 1990). During the transition from...

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“…(56). Membrane proteins were separated by sodium dodecyl sulfate--12% polyacrylamide gel electrophoresis (25) followed by staining (0.1% Coomassie blue R-250, 45% methanol, and 10% acetate) and then destaining (14% methanol and 10% acetate) procedures. Identification of the GusB and GusC proteins was achieved by N-terminal amino acid sequencing after transfer from sodium dodecyl sulfate-polyacrylamide gels to a polyvinylidene difluoride membrane (44).…”

mentioning

confidence: 99%

ThegusBCGenes ofEscherichia coliEncode a Glucuronide Transport System

et al. 2005

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Two genes, gusB and gusC, from a natural fecal isolate of Escherichia coli are shown to encode proteins responsible for transport of ␤-glucuronides with synthetic [14 C]phenyl-1-thio-␤-D-glucuronide as the substrate. These genes are located in the gus operon downstream of the gusA gene on the E. coli genome, and their expression is induced by a variety of ␤-D-glucuronides. Measurements of transport in right-side-out subcellular vesicles show the system has the characteristics of secondary active transport energized by the respirationgenerated proton motive force. When the genes were cloned together downstream of the tac operator-promoter in the plasmid pTTQ18 expression vector, transport activity was increased considerably with isopropylthiogalactopyranoside as the inducer. Amplified expression of the GusB and GusC proteins enabled visualization and identification by N-terminal sequencing of both proteins, which migrated at ca. 32 kDa and 44 kDa, respectively. Separate expression of the GusB protein showed that it is essential for glucuronide transport and is located in the inner membrane, while the GusC protein does not catalyze transport but assists in an as yet unknown manner and is located in the outer membrane. The output of glucuronides as waste by mammals and uptake for nutrition by gut bacteria or reabsorption by the mammalian host is discussed.

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[31] Assay, genetics, proteins, and reconstitution of proton-linked galactose, arabinose, and xylose transport systems of Escherichia coli

Cited by 60 publications

References 72 publications

The Hydantoin Transport Protein from Microbacterium liquefaciens

The Hydantoin Transport Protein from Microbacterium liquefaciens

Identification, Purification, and Molecular Cloning of a Putative Plastidic Glucose Translocator

ThegusBCGenes ofEscherichia coliEncode a Glucuronide Transport System

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