Hereditary Defects in Galactose Metabolism in Escherichia Coli Mutants, Ii. Galactose-Induced Sensitivity

Yarmolinsky, Michael B.; Wiesmeyer, Herbert; Kalckar, Herman Μ.; Jordan, Elizabeth

doi:10.1073/pnas.45.12.1786

Cited by 98 publications

(76 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result suggests that the enzyme is primarily involved in biosynthetic pathways rather than in the metabolism of galactose from external or internal sources. Bacterial and yeast mutants deficient in UDP-Glc epimerase are highly sensitive to galactose (Douglas and Hawthorne, 1964;Yarmolinsky et al, 1959). It has also long been known that many plants are sensitive to external application of galactose (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Mutants of Escherichia coli or yeast affected in galE or gal10, respectively, are characterized by their inability to grow on media containing galactose (Douglas and Hawthorne, 1964;Yarmolinsky et al, 1959). In humans, certain forms of galactosaemia, a pathological increase of galactose content in the blood, are caused by a defect in the UDP-Glc epimerase gene (Daude et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The role of UDP‐glucose epimerase in carbohydrate metabolism of Arabidopsis

Dörmann

Benning

1998

The Plant Journal

View full text Add to dashboard Cite

SummaryUridine 5Ј-diphospho-glucose-4-epimerase (UDP-Glc epimerase) catalyses the reversible epimerization of UDPgalactose and UDP-glucose. In contrast to bacteria and yeast, expression of the UDP-Glc epimerase gene in Arabidopsis was found not to be induced by galactose. To elucidate the metabolic role of this enzyme, transgenic Arabidopsis plants expressing the respective cDNA in sense or antisense orientation were constructed, leading to a range of plant lines with different UDP-Glc epimerase activities. No alterations in morphology were observed and the relative amounts of different galactose-containing compounds were not affected if the plants were raised on soil. However, on agar plates in the presence of galactose, the growth of different lines was increasingly repressed with decreasing enzyme activity, and an increase in the UDP-Gal content was observed in parallel, whereas the UDP-Glc content was nearly constant. The amount of galactose in the cell wall was increased in plants with low UDP-Glc epimerase activity grown on galactose, whereas the cellulose content in the leaves was not altered. Furthermore, starch determined at different times of the day was highly abundant in plants with low UDP-Glc epimerase activity in the presence of galactose. It is proposed that low endogenous UDP-Glc epimerase activity is responsible for the galactose toxicity of the wild-type. Possible mechanisms by which the starch content might be modulated are discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of UDP‐glucose epimerase in carbohydrate metabolism of Arabidopsis

Dörmann

Benning

1998

The Plant Journal

View full text Add to dashboard Cite

show abstract

“…Second, an h8-derived triple mutant, with mutations in fda gnd pgi, which does not convert glucose into fructose-6-phosphate because of blocks in the glucose-6-phosphate isomerase and the 6-phosphogluconate dehydrogenase, and therefore does not accumulate fructose-1,6-diphosphate, can grow on glucose at 42°C (50 diphosphate is toxic to cells. Accumulation of phosphorylated metabolic intermediates following growth on galactose, arabinose, or glycerol can be toxic to growing cells (9,14,15,18,31,61). The mode of action of toxic intermediates has not been determined for these systems.…”

Section: Jxci Of L-[35slmethionine-l-[35slcysteine Trans Labelmentioning

confidence: 99%

“…Thus, ppGpp is not an obligatory component of this control system. Although the effector for growth rate regulation is unknown, the fraction of ribosomes involved in active translation seems to be one element in this internal signal transduction pathway (8,29,61). Both the growth-rate and stringent responses are regulated at the level of transcription initiation (6,13,24,34,42,49,54).…”

mentioning

confidence: 99%

Physiological effects of the fructose-1,6-diphosphate aldolase ts8 mutation on stable RNA synthesis in Escherichia coli

et al. 1991

View full text Add to dashboard Cite

The conditional lethal mutations ts8 and h8 are located in fda, the gene encoding aldolase, and they inhibit RNA synthesis upon shift to the nonpermissive temperature. We demonstrate that both mutations preferentially inhibit stable RNA synthesis and that this inhibition occurs at the level of trapstription initiation. The susceptibility of a promoter to the inhibitory effects of ts8 is correlated with the ability of the promoter to be growth rate regulated. This effect is independent of relA and spoT function. Inhibition is dependent upon glucose metabolism past the generation of glucose-6-phosphate; however, the mechanism of this effect is unknown.The seven rRNA operons, which encode both tRNAs and rRNAs, are intricately regulated to ensure that the rate of ribosome synthesis is responsive to the nutritional state of the cells. The rate of stable RNA synthesis is tightly coupled both to amino acid availability and to the growth rate of the cells. Upon amino acid deprivation, the stringent response ensues, and stable RNA synthesis is immediately inhibited, probably because of a rise in the intracellular concentration of the phosphorylated nucleotide ppGpp (reviewed in references 7 and 21). In addition, the rate of stable RNA synthesis varies with the square of the growth rate, a phenomenon termed growth rate-dependent regulation (38, 39). Although circumstantial evidence has linked the intracellular concentration of ppGpp to growth rate regulation, recent studies indicate that growth rate control is manifest even in strains lacking the capacity to synthesize this nucleotide (20). Thus, ppGpp is not an obligatory component of this control system. Although the effector for growth rate regulation is unknown, the fraction of ribosomes involved in active translation seems to be one element in this internal signal transduction pathway (8,29,61). Both the growth-rate and stringent responses are regulated at the level of transcription initiation (6,13,24,34,42,49,54).The regulatory regions controlling the seven rRNA (rrn) operons are highly conserved and very complex (Fig. 1). Transcription initiation occurs from two tandem promoters. At high growth rates, ribosomal transcripts initiate primarily at the upstream promoter, termed P1, which is sensitive to both stringent and growth rate regulation. The downstream promoter, termed P2, is constitutive (47, 49). The structure of the P1 promoter has been intensively studied. The regulatory upstream activation region (UAR) is located just upstream of the P1 promoter and is required for the maximal transcription from P1 both in vivo (24) and in vitro (45,46 (24) and, in the tyrT system, the stringent response (54). A great deal of work has been devoted to defining the sequences involved in these two responses. A region located downstream of the -10 region of the promoter, termed the discriminator, has been implicated in the stringent control (54-56); however, this region is insufficient by itself to confer stringent regulation on a promoter (33,63). Several positions in the pr...

show abstract

“…Although it has been the subject of decades of research, knowledge of the mechanisms controlling glycolytic flux are still incomplete, even in the well studied model organism Escherichia coli. Numerous studies have noted that bacterial strains with an impaired capacity to metabolize phosphorylated sugars (including some of the substrates of glycolysis) often show strong phenotypes of growth inhibition or in some cases cell lysis (1)(2)(3). However, until recently, little was known about the mechanisms used by bacterial cells to deal with metabolic stress associated with intracellular phosphosugar accumulation.…”

mentioning

confidence: 99%

A dual function for a bacterial small RNA: SgrS performs base pairing-dependent regulation and encodes a functional polypeptide

Wadler

Vanderpool

2007

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

279

288

View full text Add to dashboard Cite

SgrS is a 227-nt small RNA that is expressed in Escherichia coli during glucose-phosphate stress, a condition associated with intracellular accumulation of glucose-6-phosphate caused by disruption of glycolytic flux. Under stress conditions, SgrS negatively regulates translation and stability of the ptsG mRNA, encoding the major glucose transporter, by means of a base pairing-dependent mechanism requiring the RNA chaperone Hfq. SgrS activity mitigates the effects of glucose-phosphate stress, and the present study has elucidated a function of SgrS that is proposed to contribute to the stress response. The 5 end of SgrS, upstream of the nucleotides involved in base pairing with the ptsG mRNA, contains a 43-aa ORF, sgrT, that is conserved in most species that contain SgrS-like small RNAs. The sgrT gene is translated in E. coli under conditions of glucose-phosphate stress. Analysis of alleles that separate the base pairing function of SgrS from the sgrT coding sequence revealed that either of these functions alone are sufficient for previously characterized SgrS phenotypes. SgrSdependent down-regulation of ptsG mRNA stability does not require SgrT and SgrT by itself has no effect on ptsG mRNA stability. Cells expressing sgrT alone had a defect in glucose uptake even though they had nearly wild-type levels of PtsG (IICB Glc ). Together, these data suggest that SgrS represents a previously unrecognized paradigm for small RNA (sRNA) regulators as a bifunctional RNA that encodes physiologically redundant but mechanistically distinct functions contributing to the same stress response.riboregulation ͉ RNA stability ͉ small proteins ͉ phosphoenolpyruvate phosphotransferase system ͉ glycolytic flux

show abstract

Hereditary Defects in Galactose Metabolism in Escherichia Coli Mutants, Ii. Galactose-Induced Sensitivity

Abstract: 26 The composition per liter volume is as follows: galactose, 10 gm.; casein digest, 8 gm.; yeast extract, 1 gm.; sodium chloride, 5 gm.; K3HPO4, 2 gm.; eosin Y, 0.4 gm.; methylene blue, 0.065 gm. and agar 15 gm.; 20 to 25 ml. was used for a Petri plate, according to Lederberg, J.

Cited by 98 publications

References 6 publications

The role of UDP‐glucose epimerase in carbohydrate metabolism of Arabidopsis

The role of UDP‐glucose epimerase in carbohydrate metabolism of Arabidopsis

Physiological effects of the fructose-1,6-diphosphate aldolase ts8 mutation on stable RNA synthesis in Escherichia coli

A dual function for a bacterial small RNA: SgrS performs base pairing-dependent regulation and encodes a functional polypeptide

Contact Info

Product

Resources

About