Phosphoenolpyruvate-dependent sugar phosphotransferase activity in Megasphaera elsdenii

1981 ◽  
Vol 27 (9) ◽  
pp. 949-952 ◽  
Author(s):  
Steven S. Dills ◽  
Catherine A. Lee ◽  
Milton H. Saier Jr.
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Enteric Bacteria ◽  
Cross Reactivity ◽  
Physical Characteristics ◽  
Sugar Uptake ◽  
Phosphotransferase System ◽  
Substrate Specificities ◽  
Megasphaera Elsdenii

Megasphaera elsdenii was found to possess an inducible phosphoenolpyruvate:sugar phosphotransferase system for glucose and fructose but not for other hexoses, hexosamines, or hexitols. The complexity of the Megasphaera phosphoenolpyruvate:sugar phosphotransferase system lies intermediate to systems found in photoautotrophic bacteria and enteric bacteria. Megasphaera elsdenii phosphotransferase proteins exhibited enzymatic cross-reactivity with those from Escherichia coli; however, differences were found in substrate specificities and the physical characteristics of the proteins from these organisms. Sugar uptake was reduced in M. elsdenii stationary-phase as compared with log-phase cells and this loss correlated with a reduction in enzyme II function.

scholarly journals Stationary-Phase Regulation of RpoS Translation in Escherichia coli

2005 ◽  
Vol 187 (21) ◽  
pp. 7204-7213 ◽  
Author(s):  
Matthew Hirsch ◽  
Thomas Elliott
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Osmotic Shock ◽  
Transcriptional Response ◽  
Enteric Bacteria ◽  
Protein Activity ◽  
E Coli ◽  
Phase Regulation ◽  
Shine Dalgarno Sequence ◽  
Necessary And Sufficient

ABSTRACT In enteric bacteria, adaptation to a number of different stresses is mediated by the RpoS protein, one of several sigma factors that collectively allow a tailored transcriptional response to environmental cues. Stress stimuli including low temperature, osmotic shock, nutrient limitation, and growth to stationary phase (SP) all result in a substantial increase in RpoS abundance and activity. The mechanism of regulation depends on the specific signal but may occur at the level of transcription, translation, protein activity, or targeted proteolysis. In both Escherichia coli and Salmonella enterica, SP induction of RpoS in rich medium is >30 fold and includes effects on both transcription and translation. Recently, we found that SP control of rpoS transcription in S. enterica involves repression of the major rpoS promoter during exponential phase by the global transcription factor Fis. Working primarily with E. coli, we now show that 24 nucleotides of the rpoS ribosome-binding site (RBS) are necessary and sufficient for a large part of the increase in rpoS translation as cells grow to SP. Genetic evidence points to an essential role for the leader nucleotides just upstream of the Shine-Dalgarno sequence but is conflicted on the question of whether sequence or structure is important. SP regulation of rpoS is conserved between E. coli and S. enterica. When combined with an fis mutation to block transcriptional effects, replacement of the rpoS RBS sequence by the lacZ RBS eliminates nearly all SP induction of RpoS.

scholarly journals Role of rpoS in the regulation of glyoxalase III in Escherichia coli.

2004 ◽  
Vol 51 (3) ◽  
pp. 857-860 ◽  
Author(s):  
Ludmil Benov ◽  
Fatima Sequeira ◽  
Anees F Beema
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Enteric Bacteria ◽  
Glyoxalase I ◽  
Aldehyde Reductase ◽  
E Coli ◽  
Rpos Mutant ◽  
Phosphorylated Sugars ◽  
Glyoxalase Iii

Methylglyoxal is an endogenous electrophile produced in Escherichia coli by the enzyme methylglyoxal synthase to limit the accumulation of phosphorylated sugars. In enteric bacteria methylglyoxal is detoxified by the glutathione-dependent glyoxalase I/II system, by glyoxalase III, and by aldehyde reductase and alcohol dehydrogenase. Here we demonstrate that glyoxalase III is a stationary-phase enzyme. Its activity reached a maximum at the entry into the stationary phase and remained high for at least 20 h. An rpoS- mutant displayed normal glyoxalase I and II activities but was unable to induce glyoxalase III in stationary phase. It thus appears that glyoxalase III is regulated by rpoS and might be important for survival of non-growing E. coli cultures.

scholarly journals Suppression of the ptsH Mutation inEscherichia coli and Salmonella typhimurium by a DNA Fragment from Lactobacillus casei

1998 ◽  
Vol 180 (19) ◽  
pp. 5247-5250
Author(s):  
Vicente Monedero ◽  
Pieter W. Postma ◽  
Gaspar Pérez-Martínez
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Lactobacillus Casei ◽  
Protein A ◽  
Constitutive Expression ◽  
Enteric Bacteria ◽  
Inescherichia Coli ◽  
Phosphotransferase System ◽  
Dna Fragment ◽  
General Component

ABSTRACT A DNA fragment from Lactobacillus casei that restores growth to Escherichia coli and Salmonella typhimurium ptsH mutants on glucose and other substrates of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) has been isolated. These mutants lack the HPr protein, a general component of the PTS. Sequencing of the cloned fragment revealed the absence ofptsH homologues. Instead, the complementation ability was located in a 120-bp fragment that contained a sequence homologue to the binding site of the Cra regulator from enteric bacteria. Experiments indicated that the reversion of the ptsH phenotype was due to a titration of the Cra protein, which allowed the constitutive expression of the fructose operon.

scholarly journals Adaptive reversion of a frameshift mutation in Escherichia coli.

Genetics ◽  
1991 ◽  
Vol 128 (4) ◽  
pp. 695-701 ◽  
Author(s):  
J Cairns ◽  
P L Foster
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Frameshift Mutation ◽  
Rare Event ◽  
Lacz Fusion ◽  
Mutation Rates ◽  
Classical Studies ◽  
Selective Forces

Abstract Mutation rates are generally thought not to be influenced by selective forces. This doctrine rests on the results of certain classical studies of the mutations that make bacteria resistant to phages and antibiotics. We have studied a strain of Escherichia coli which constitutively expresses a lacI-lacZ fusion containing a frameshift mutation that renders it Lac-. Reversion to Lac+ is a rare event during exponential growth but occurs in stationary cultures when lactose is the only source of energy. No revertants accumulate in the absence of lactose, or in the presence of lactose if there is another, unfulfilled requirement for growth. The mechanism for such mutation in stationary phase is not known, but it requires some function of RecA which is apparently not required for mutation during exponential growth.

scholarly journals 31phospho-NMR demonstration of phosphocysteine as a catalytic intermediate on the Escherichia coli phosphotransferase system EIIMtl.

1991 ◽  
Vol 266 (11) ◽  
pp. 6690-6692
Author(s):  
H H Pas ◽  
G H Meyer ◽  
W H Kruizinga ◽  
K S Tamminga ◽  
R P van Weeghel ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Phosphotransferase System
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