Home. Bioenergetics and Metabolism; Cell Biology; Development and Disease; Genes; Molecular Struc... more Home. Bioenergetics and Metabolism; Cell Biology; Development and Disease; Genes; Molecular Structure and Function; Signal Transduction. About: Mission statement; Aims and scope; Honorary Editor; Advisory Panel; COPE; News; Portland Press: Biochemical Journal: Current Issue; Reviews. Clinical Science. Contact; Terms and conditions of usage; Rights and permissions; Disclaimer. Gateways: Bioenergetics and Metabolism; Cell Biology; Development ...
ABSTRACT Thiamine enhances growth of the meat spoilage organism, Brochothrix thermosphacta. It fu... more ABSTRACT Thiamine enhances growth of the meat spoilage organism, Brochothrix thermosphacta. It fulfils some, but not all, of the yeast-extract requirement of this organism. Oxythiamine acts as a growth inhibitor at high concentrations and the inhibition is readily reversed by thiamine. The possible roles of thiamine in the metabolism of Br. thermosphacta are discussed.
... 710 April 1992. Communication. Nucleoside transporters in human placenta. L. FELIPE BARROS,... more ... 710 April 1992. Communication. Nucleoside transporters in human placenta. L. FELIPE BARROS, NICK BEAUMONT, SIMON M. JARVIS#, JAMES D ... School of Medicine (University of London), Rowland Hill Street, London NW3 2PF, UK, #University of Kent, Canterbury, Kent ...
Summary l‐Fucose (6‐deoxy‐l‐galactose) is used as sole carbon source by many microorganisms, and ... more Summary l‐Fucose (6‐deoxy‐l‐galactose) is used as sole carbon source by many microorganisms, and its transport into Escherichia coli is mediated by An l‐fucose‐H+ symport activity, in order to determine the nature of a putative transporter encoded by the E. coli fucP gene and Identify its protein product it was cloned downstream of the inducible T7 RNA polymerase and lambda Ol Pl promoters, induction of the T7 promoter resulted in the expression of [14C]‐l‐fucose uptake activity and the concomitant expression of a [35S]‐Met‐labelled 32 kDa protein at levels too tow for detection by staining with Coomassie briiiiant blue or for protein sequencing, induction of the lambda Ol Pl promoter caused the appearance of l‐fucose‐H+ symport activity and of a Coomassie brilliant blue‐stained 32 kDa membrane protein expressed at high levels sufficient for identification as FucP by N‐terminal protein sequencing. The FucP protein is, therefore, a sugar‐H+ symporter different in amino acid sequence from any other known transporter. These and other results illustrate the general unpredictability of cloning strategies for attempting the amplified expression of membrane transport proteins.
The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH chang... more The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH change which failed to appear in the presence of uncoupling agents. Accumulation of [14C]xylose by energy-replete cells was also inhibited by uncoupling agents, but not by fluoride or arsenate. Subcellular vesicles of E. coli accumulated [14C]xylose provided that ascorbate plus phenazine methosulfate were present for respiration, and this accumulation was inhibited by uncoupling agents or valinomycin. Therefore, the transport of xylose into E. coli appears to be energized by a proton-motive force, rather than by a phosphotransferase or directly energized mechanism. Its specificity for xylose as inducer and substrate and the genetic location of a xylose-H+ transport-negative mutation near mtl showed that the xylose-H+ system is distinct from other proton-linked sugar transport systems of E. coli.
Proceedings of the National Academy of Sciences, 2019
Significance Multidrug efflux pumps are highly promiscuous determinants of antimicrobial resistan... more Significance Multidrug efflux pumps are highly promiscuous determinants of antimicrobial resistance in bacterial pathogens. Since efflux pumps evolved long before the widespread use of antimicrobials, drug transport is likely to be a side reaction in many pumps, fortuitously beneficial to bacteria in hospitals. The AceI efflux protein from Acinetobacter baumannii is the prototype for the proteobacterial antimicrobial compound efflux (PACE) family. AceI was only known to transport the synthetic biocide chlorhexidine, which was incongruous with its ancient origin. Here we demonstrate that short-chain diamines are the physiological substrates of AceI and other PACE members, and that transport is energized by an electrochemical gradient of protons. These observations are important, because diamines play vital roles in bacterial physiology and virulence and have significant commercial uses.
Home. Bioenergetics and Metabolism; Cell Biology; Development and Disease; Genes; Molecular Struc... more Home. Bioenergetics and Metabolism; Cell Biology; Development and Disease; Genes; Molecular Structure and Function; Signal Transduction. About: Mission statement; Aims and scope; Honorary Editor; Advisory Panel; COPE; News; Portland Press: Biochemical Journal: Current Issue; Reviews. Clinical Science. Contact; Terms and conditions of usage; Rights and permissions; Disclaimer. Gateways: Bioenergetics and Metabolism; Cell Biology; Development ...
ABSTRACT Thiamine enhances growth of the meat spoilage organism, Brochothrix thermosphacta. It fu... more ABSTRACT Thiamine enhances growth of the meat spoilage organism, Brochothrix thermosphacta. It fulfils some, but not all, of the yeast-extract requirement of this organism. Oxythiamine acts as a growth inhibitor at high concentrations and the inhibition is readily reversed by thiamine. The possible roles of thiamine in the metabolism of Br. thermosphacta are discussed.
... 710 April 1992. Communication. Nucleoside transporters in human placenta. L. FELIPE BARROS,... more ... 710 April 1992. Communication. Nucleoside transporters in human placenta. L. FELIPE BARROS, NICK BEAUMONT, SIMON M. JARVIS#, JAMES D ... School of Medicine (University of London), Rowland Hill Street, London NW3 2PF, UK, #University of Kent, Canterbury, Kent ...
Summary l‐Fucose (6‐deoxy‐l‐galactose) is used as sole carbon source by many microorganisms, and ... more Summary l‐Fucose (6‐deoxy‐l‐galactose) is used as sole carbon source by many microorganisms, and its transport into Escherichia coli is mediated by An l‐fucose‐H+ symport activity, in order to determine the nature of a putative transporter encoded by the E. coli fucP gene and Identify its protein product it was cloned downstream of the inducible T7 RNA polymerase and lambda Ol Pl promoters, induction of the T7 promoter resulted in the expression of [14C]‐l‐fucose uptake activity and the concomitant expression of a [35S]‐Met‐labelled 32 kDa protein at levels too tow for detection by staining with Coomassie briiiiant blue or for protein sequencing, induction of the lambda Ol Pl promoter caused the appearance of l‐fucose‐H+ symport activity and of a Coomassie brilliant blue‐stained 32 kDa membrane protein expressed at high levels sufficient for identification as FucP by N‐terminal protein sequencing. The FucP protein is, therefore, a sugar‐H+ symporter different in amino acid sequence from any other known transporter. These and other results illustrate the general unpredictability of cloning strategies for attempting the amplified expression of membrane transport proteins.
The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH chang... more The addition of xylose to energy-depleted cells of Escherichia coli elicited an alkaline pH change which failed to appear in the presence of uncoupling agents. Accumulation of [14C]xylose by energy-replete cells was also inhibited by uncoupling agents, but not by fluoride or arsenate. Subcellular vesicles of E. coli accumulated [14C]xylose provided that ascorbate plus phenazine methosulfate were present for respiration, and this accumulation was inhibited by uncoupling agents or valinomycin. Therefore, the transport of xylose into E. coli appears to be energized by a proton-motive force, rather than by a phosphotransferase or directly energized mechanism. Its specificity for xylose as inducer and substrate and the genetic location of a xylose-H+ transport-negative mutation near mtl showed that the xylose-H+ system is distinct from other proton-linked sugar transport systems of E. coli.
Proceedings of the National Academy of Sciences, 2019
Significance Multidrug efflux pumps are highly promiscuous determinants of antimicrobial resistan... more Significance Multidrug efflux pumps are highly promiscuous determinants of antimicrobial resistance in bacterial pathogens. Since efflux pumps evolved long before the widespread use of antimicrobials, drug transport is likely to be a side reaction in many pumps, fortuitously beneficial to bacteria in hospitals. The AceI efflux protein from Acinetobacter baumannii is the prototype for the proteobacterial antimicrobial compound efflux (PACE) family. AceI was only known to transport the synthetic biocide chlorhexidine, which was incongruous with its ancient origin. Here we demonstrate that short-chain diamines are the physiological substrates of AceI and other PACE members, and that transport is energized by an electrochemical gradient of protons. These observations are important, because diamines play vital roles in bacterial physiology and virulence and have significant commercial uses.
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