Mu d1(Ap lac)-generated operon fusions were used in the identification of genes Escherichia coli whose transcriptional expression is altered by changes osmolarity growth medium. One such osmoresponsive gene, designated osrA, was induced 400-fold when medium increased with addition either ionic or neutral impermeable solutes but not glycerol, which freely permeable across cell membrane. osrA mapped to 57.5 min and shown be transcribed clockwise on E. chromosome. The ability small...

Two pathways of transcription termination, factor-independent and -dependent, exist in bacteria. The latter pathway operates on nascent transcripts that are not simultaneously translated requires factors Rho, NusG, NusA, each which is essential for viability WT Escherichia coli . NusG NusA also involved antitermination at the ribosomal RNA operons, as well regulating rates elongation all genes. We have used a bisulfite-sensitivity assay to demonstrate genome-wide increase occurrence RNA-DNA...

Salt-induced overexpression of genes cloned downstream the phage T7 phi10 promoter was demonstrated in an Escherichia coli strain (GJ1158) which carries a single chromosomally integrated copy gene for RNA polymerase under transcriptional control cis-regulatory elements osmoresponsive proU operon. Plasmids that have been constructed to obtain overproduction individual target products BL21(DE3) (by addition isopropyl-beta-D-thiogalactopyranoside as inducer) can directly be transformed into...

The sequence of 4,362 nucleotides encompassing the proU operon Escherichia coli was determined. Three open reading frames were identified whose orientation, order, location, and sizes in close accord with genetic evidence for three cistrons (proV, proW, proX) this operon. Similarities primary structure observed between (i) deduced ProV membrane-associated components other binding-protein-dependent transport systems, nucleotide-binding region each latter proteins, (ii) that ProW integral...

The endonuclease RNase E of Escherichia coli is essential for viability, but deletion its C-terminal half (CTH) not lethal. preferentially acts on 5'-monophosphorylated RNA whose generation from primary transcripts catalysed by RppH, ΔRppH strains are viable. Here we show that the E-ΔCTH combination lethal, and lethality suppressed rho or nusG mutations impairing Rho-dependent transcription termination. Lethality was correlated with defects in bulk mRNA decay tRNA processing, which were...

Nascent untranslated transcripts in bacteria are prone to generating RNA-DNA hybrids (R-loops); Rho-dependent transcription termination acts reduce their prevalence. Here we discuss the mechanisms of R-loop formation and growth inhibition bacteria.

The anonymous open reading frame yggA of Escherichia coli was identified in this study as a gene that is under the transcriptional control argP (previously called iciA), which encodes LysR-type regulator protein. Strains with null mutations either or were supersensitive to arginine analog canavanine, and yggA-lac expression vivo exhibited argP(+)-dependent induction by arginine. Lysine supplementation phenocopied mutation it virtually abolished expression, even argP+ strain. dipeptides...

Kdp, an inducible high-affinity K+ transporter in Escherichia coli, is encoded by genes of the kdpABC operon, and its expression regulated products kdpD kdpE. Loss cell turgor has been proposed to be signal which induces kdp (L. A. Laimins, D. B. Rhoads, W. Epstein, Proc. Natl. Acad. Sci. USA 78:464-468, 1981). We reexamined during steady-state growth under a variety conditions were able confirm earlier observations had indicated that it primarily affected concentration medium mutations...

Transcription of the proU operon in Escherichia coli is induced several hundredfold upon growth cells media elevated osmolarity. A low-copy-number promoter-cloning plasmid vector, with lacZ as reporter gene, was used for assaying osmoresponsive promoter activity each various lengths DNA, generated by cloning discrete restriction fragments and an exonuclease III-mediated deletion approach. The results indicate that expression E. directed from two promoters, one (P2) characterized earlier...

The Dam DNA methylase of Escherichia coli is required for methyl-directed mismatch repair, regulation chromosomal replication initiation from oriC (which DnaA-dependent), and gene expression. Here, we show that suppresses aberrant oriC-independent (also called constitutive stable replication, or cSDR). deficiency conferred cSDR and, in presence additional mutations (Δtus, rpoB*35) facilitate retrograde fork progression, rescued the lethality ΔdnaA mutants. DinG helicase was rescue...

Abstract The essential homotetrameric endoribonuclease RNase E of Escherichia coli participates in global RNA turnover as well stable maturation. protomer’s N-terminal half (residues 1–529) bears the catalytic, allosteric, and tetramerization domains, including active site residues D303 D346. C-terminal (CTH, 530–1061) is dispensable for viability. We have previously described a phenomenon recessive resurrection that requires CTH, wherein wild-type homotetramer apparently displays nearly...

The proU locus in Escherichia coli encodes an osmotically inducible transport system for two substrates, glycine betaine and L-proline, whose intracellular accumulation represents important component the physiology of osmoregulation. Several osmoresponsive proU::lac mutants were isolated tested complementation with plasmids carrying different functional regions proU. Three classes mutations identified which physically mapped to distinct DNA from this locus. Tn1000-insertion mutagenesis...

Bacteriophage lambda ppheA-lac was used to obtain strains of Escherichia coli K-12 in which pheA and lacZ are each transcribed from a separate promoter. Mutants both beta-galactosidase chorismate mutase P-prephenate dehydratase (the gene product) were derepressed isolated, transacting (pheR) identified. pheR mapped at min 93 on the E. chromosome; mutants acquired wild-type phenotype when either F117 (which covers 93-min region) or F116 59 65) introduced into cell. A rifampin resistance...

Nascent transcripts in Escherichia coli that fail to be simultaneously translated are subject a factor-dependent mechanism of termination (also termed polarity) involves the proteins Rho and NusG. In this study, we found overexpression YdgT suppressed polarity relief phenotypes restored efficiency rho or nusG mutants. Hha belong H-NS StpA family repress large number genes Gram-negative bacteria. Variants defective one other its two dimerization domains, but not those DNA binding alone, also...

Transcription termination by Rho is essential for viability in various bacteria, including some major pathogens. Since acts targeting nascent RNAs that are not simultaneously translated, it also regulates antisense transcription. Here we show RNase H-deficient mutants of Escherichia coli exhibit heightened sensitivity to the inhibitor bicyclomycin, and deficiency provokes increased formation RNA-DNA hybrids (R-loops) which ameliorated expression phage T4-derived R-loop helicase UvsW. We...

Transcription of the proU operon Escherichia coli is induced several hundred-fold upon growth at elevated osmolarity, but underlying mechanisms are incompletely understood. Three cis elements appear to act additively mediate osmoresponsivity: (i) sequences around a promoter, P1, which situated 250 bp upstream first structural gene proV; (ii) another (sigma 70-dependent) P2, 60 and (iii) negative regulatory element present within proV coding region. These three designated, respectively, P1R,...

The growth of Escherichia coli strains in media having elevated osmolarity was promoted the presence low concentrations L-proline analog 5-hydroxy-L-pipecolic acid. osmoprotective ability this compound correlated with these a functional proP+ gene. results suggest that proP-mediated transport (in addition to by proU) is important osmoregulation. proP::lac operon fusions were used demonstrate gene shows limited induction expression upon and it transcribed clockwise on chromosome.

We have used supercoiled DNA templates in this study to demonstrate that transcription vitro from the P1 and P2 promoters of osmoresponsive proU operon Escherichia coli is preferentially mediated by sigma(s) sigma70-bearing RNA polymerase holoenzymes, respectively. Addition potassium glutamate resulted activation both also led a pronounced enhancement selectivity at promoter. Transcription P2, lesser extent P1, was inhibited nucleoid protein H-NS but only absence glutamate. This validates...

The radiation sensitivity of Escherichia coli B was first described more than 50 years ago, and the genetic locus responsible for trait subsequently identified as lon (encoding Lon protease). We now show that both E. reported K-12 mutant, AB1899, carry IS186 insertions in opposite orientations at a single site promoter region this represents natural hot spot transposition insertion sequence (IS) element. Our analysis deposited data number other sites permitted deductions (i) consensus target...

The proU locus in Escherichia coli encodes an important osmoregulatory function which mediates the growth-promoting effect of L-proline and glycine betaine high-osmolarity media. This was cloned, contiguity with a closely linked Tn10 insertion, onto multicopy plasmid directly from E. chromosome. For given level osmotic stress, magnitude osmoresponsive induction single-copy proU::lac fusion reduced strains multiple copies proU+ genes; comparison haploid strains, plasmids also exhibited...