The repression of trehalose transport and metabolism in Escherichia coli by high osmolarity is mediated by trehalose-6-phosphate phosphatase

Klein, W.; Ehmann, U; Boos, Winfried

doi:10.1016/0923-2508(91)90105-j

Cited by 27 publications

(25 citation statements)

References 14 publications

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“…At high osmolarity, OtsA and OtsB are present at high levels and synthesize internal trehalose from UDPglucose and glucose 6-phosphate (46). At the same time, the TreB-mediated uptake of trehalose as trehalose-6-phosphate and its TreC-mediated hydrolysis to glucose and glucose 6-phosphate are prevented by the OtsB-mediated removal of internal trehalose-6-phosphate, this compound being the inducer of the treB-treC operon (28) …”

Section: Discussionmentioning

confidence: 99%

“…Thus, the activity of OtsB that eliminates trehalose-6-phosphate nonproductively (forming nonmetabolizable internal trehalose) will greatly affect growth on trehalose. We have demonstrated previously that the high activity of this enzyme under high-osmolarity growth conditions is responsible for the reduction of treB-treC expression at high osmolarity because of the lack of induction of treB-treC by internal trehalose-6-phosphate (28).…”

Section: Discussionmentioning

confidence: 99%

“…Glucose 6-phosphate and glucose (after being phosphorylated by glucokinase) then enter glycolysis. TreB (EII re) and TreC are both induced by trehalose-6-phosphate (28). The genes treB and treC form an operon, treB being the promoter-proximal gene of the operon.…”

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Trehalose-6-phosphate hydrolase of Escherichia coli

1994

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The disaccharide trehalose acts as an osmoprotectant as well as a carbon source in Escherichia coli. At high osmolarity of the growth medium, the cells synthesize large amounts of trehalose internally as an osmoprotectant. However, they can also degrade trehalose as the sole source of carbon under both high-and low-osmolarity growth conditions. The modes of trehalose utilization are different under the two conditions and have to be well regulated (W. Boos, U. Ehmann, H. Forkl, W. Klein, M. Rimmele, and P. Postma, J. Bacteriol. 172:3450-3461, 1990). At low osmolarity, trehalose is transported via a trehalose-specific enzyme II of the phosphotransferase system, encoded by treB. The trehalose-6-phosphate formed internally is hydrolyzed to glucose and glucose 6-phosphate by the key enzyme of the system, trehalose-6-phosphate hydrolase, encoded by treC. We have cloned treC, contained in an operon with treB as the promoter-proximal gene. We have overproduced and purified the treC gene product and identified it as a protein consisting of a single polypeptide with an apparent molecular weight of 62,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme hydrolyzes trehalose-6-phosphate with a Km of 6 mM and a V.. of at least 5.5iimol of trehalose-6-phosphate hydrolyzed per min per mg of protein. The enzyme also very effectively hydrolyzes p-nitrophenyl-a-D-glucopyranoside, but it does not recognize trehalose, sucrose, maltose, isomaltose, or maltodextrins. treC was sequenced and found to encode a polypeptide with a calculated molecular weight of 63,781. The amino acid sequence deduced from the DNA sequence shows homology (50%6 identity) with those of oligo-1,6-glucosidases (sucrase-isomaltases) of Bacilus spp. but not with those of other disaccharide phosphate hydrolases. This report corrects our previous view on the function of the treC gene product as an amylotrehalase, which was based on the analysis of the metabolic products of trehalose metabolism in whole cells.The disaccharide trehalose serves as an osmoprotectant in many different organisms. Its two glucose molecules are linked 1-1 oa-glycosidically. Thus, the sugar is nonreducing and has the unique quality of maintaining the fluidity of membranes under conditions of dryness and desiccation (16,17). In Escherichia coli, trehalose is synthesized internally as an answer to osmotic stress (23,45,48). Among other, more prominent osmoprotectants such as glycine betaine or proline (11,36), trehalose can contribute up to 20% of the entire capacity for osmotic protection of the cell (21, 32). To synthesize the osmoprotectant trehalose at high osmolarity, UDP-glucose and glucose 6-phosphate are used to form trehalose-6-phosphate, regardless of the carbon source. Trehalose-6-phosphate is subsequently dephosphorylated to give free trehalose. Trehalose-6-phosphate synthase is encoded by otsA (osmotic trehalose synthesis), and trehalose-6-phosphate phosphatase is encoded by otsB. The two genes are localized at 42 min on the chromosome, otsB...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Trehalose-6-phosphate hydrolase of Escherichia coli

1994

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“…Third, in case of prolonged osmotic stress, E. coli can take up the osmoprotectants glycine betaine and proline from the environment via the proVWX-encoded ABC transporter or synthesize glycine betaine from the extracellular precursor choline 2,9,10 . Fourth, if no extracellular compatible solutes are available, E. coli induces expression of trehalose-6-phosphate synthase (OtsA) and phosphatase (OtsB) to produce high intracellular concentrations of the nonreducing disaccharide trehalose from the precursors UDP-glucose and glucose 6-phosphate, conveying long-term resistance to sustained osmotic stress [11][12][13] . Quantitative studies indicated, however, that the amounts of compatible solutes produced by E. coli may not be sufficient to maintain cell turgor exclusively based on increasing intracellular osmolality, implying accompanying effects such as molecular crowding 14 .…”

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confidence: 99%

Ubiquinone accumulation improves osmotic-stress tolerance in Escherichia coli

2014

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Bacteria are thought to cope with fluctuating environmental solute concentrations primarily by adjusting the osmolality of their cytoplasm. To obtain insights into underlying metabolic adaptions, we analyzed the global metabolic response of Escherichia coli to sustained hyperosmotic stress using non-targeted mass spectrometry. We observed that 52% of 1,071 detected metabolites, including known osmoprotectants, changed abundance with increasing salt challenge. Unexpectedly, unsupervised data analysis revealed a substantial increase of most intermediates in the ubiquinone-8 (Q8) biosynthesis pathway and a 110-fold accumulation of Q8 itself, as confirmed by quantitative lipidomics. We then demonstrate that Q8 is necessary for acute and sustained osmotic stress tolerance using Q8 mutants and tolerance rescue through feeding non-respiratory Q8 analogues. Finally, in vitro experiments with artificial liposomes reveal mechanical membrane stabilization as a principal mechanism of Q8-mediated osmoprotection. Thus, we find that besides regulating intracellular osmolality, E. coli enhances its cytoplasmic membrane stability to withstand osmotic stress. AbstractBacteria are thought to cope with fluctuating environmental solute concentrations primarily by adjusting the osmolality of their cytoplasm. To obtain insights into underlying metabolic adaptions, we analyzed the global metabolic response of Escherichia coli to sustained hyperosmotic stress using non-targeted mass spectrometry. We observed that 52% of 1,071 detected metabolites, including known osmoprotectants, changed abundance with increasing salt challenge. Unexpectedly, unsupervised data analysis revealed a substantial increase of most intermediates in the ubiquinone-8 (Q8) biosynthesis pathway and a 110-fold accumulation of Q8 itself, as confirmed by quantitative lipidomics. We then demonstrate that Q8 is necessary for acute and sustained osmotic stress tolerance using Q8 mutants and tolerance rescue through feeding non-respiratory Q8 analogues.Finally, in vitro experiments with artificial liposomes reveal mechanical membrane stabilization as a principal mechanism of Q8-mediated osmoprotection. Thus, we find that besides regulating intracellular osmolality, E. coli enhances its cytoplasmic membrane stability to withstand osmotic stress.

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“…Their internal inducer is trehalose-6-phosphate; therefore, these genes are not expressed under osmotic stress when the osmoregulatory trehalose-6-phosphate phosphatase is operative (27). A mutation which seems to influence expression of otsA, otsP (otsB), and treC, but not treB, has been mapped to 84 min, but the nature of this gene remains unclear (27).…”

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Molecular cloning and physical mapping of the otsBA genes, which encode the osmoregulatory trehalose pathway of Escherichia coli: evidence that transcription is activated by katF (AppR)

Kaasen¹,

Falkenberg²,

Styrvold³

et al. 1992

J Bacteriol

198

155

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It has been shown previously that the otsA and otsB mutations block osmoregulatory trehalose synthesis in Escherichia coli. We report that the transcription of these osmoregulated ots genes is dependent on KatF (AppR), a putative sigma factor for certain stationary phase-and starvation-induced genes. The transcription of the osmoregulated bet and proU genes was not katF dependent. Our genetic analysis showed that katF carries an amber mutation in E. coli K-12 and many of its derivatives but that katF has reverted to an active form in the much-used strain MC4100. This amber mutation in katF leads to strain variations in trehalose synthesis and other katF-dependent functions of E. coli. We have performed a molecular cloning of the otsBA genes, and we present evidence that they constitute an operon encoding trehalose-6-phosphate phosphatase and trehalose-6-phosphate synthase. A cloning and restriction site analysis, performed by comparing the cloned fragments with the known physical map of the E. coli chromosome, revealed that the otsBA genes are situated on a 2.9-kb HindIII fragment located 8 to 11 kb clockwise of tar (41.6 min).Trehalose, a nonreducing disaccharide of glucose, is a stress metabolite in various organisms (29). Saccharomyces cerevisiae accumulates trehalose when exposed to an elevated temperature of growth (3,24) or to hazardous chemical agents such as ethanol, copper sulfate, or hydrogen peroxide (3). Rhizobia accumulate trehalose when stressed with lowoxygen (e.g., 1%) tension, regardless of the composition of the growth medium (23). Many phototrophic and heterotrophic bacteria, including Escherichia coli, accumulate trehalose in response to osmotic stress (18,31,45,50). Trehalose is shown to preserve the function and integrity of biological membranes exposed to conditions of low water activity (14) and to confer desiccation tolerance to yeasts (24), to spores of Streptomyces sp. (36), and to nematodes (14); frost tolerance to insects (2) and yeasts (22); and osmotic tolerance to E. coli (19). In yeasts, trehalose accumulation during growth in liquid culture coincides with an increased plating efficiency on agar plates of low water activity (34).In E. coli, the osmoregulatory trehalose pathway consists of a trehalose-6-phosphate synthase which converts UDPglucose and glucose-6-phosphate to trehalose-6-phosphate and a phosphatase which dephosphorylates this metabolic intermediate (reference 19 and this study). Two insertion mutations, named otsA and otsB, which block the synthesis of the synthase, have previously been mapped to 42 min, but the trehalose-6-phosphate phosphatase activity of these mutants was not reported (19). However, a point mutation named otsP which causes accumulation of trehalose-6-phosphate in stressed cells, presumably because of a defective phosphatase, was mapped near otsA (27). This mutation appears to be allelic with otsB (reference 27 and this study).Trehalose accumulation in stressed cells of E. coli is regulated at several levels. Experiments with lac fusions have show...

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The repression of trehalose transport and metabolism in Escherichia coli by high osmolarity is mediated by trehalose-6-phosphate phosphatase

Cited by 27 publications

References 14 publications

Trehalose-6-phosphate hydrolase of Escherichia coli

Trehalose-6-phosphate hydrolase of Escherichia coli

Ubiquinone accumulation improves osmotic-stress tolerance in Escherichia coli

Molecular cloning and physical mapping of the otsBA genes, which encode the osmoregulatory trehalose pathway of Escherichia coli: evidence that transcription is activated by katF (AppR)

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