Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

S. tyrphimurium strain BY324 is temperature sensitive due to a mutation (rpo C32) in the gene for the RNA polymerase beta' subunit. Transcription of T7 DNA by RNA polymerase purified from this strain is temperature sensitive in vitro. The enzyme is slightly defective in template binding and RNA chain initiation, but the major defect is in RNA chain elongation. The rate of RNA chain elongation is reduced 4-5 fold relative to wild-type. RNA chain termination does not appear to be affected by the beta' mutation. While the elongation defect is suppressed by glycerol or dimethylsulfoxide, the initiation defect is not. Possible roles for the beta' subunit in enzyme function are discussed in light of these results.
Mol Gen Genet 1977 Oct 20
PMID:Multiple effects of an RNA polymerase beta' mutation on in vitro transcription. 33 27

Specific transformation of a rifampicin sensitive strain of Escherichia coli to rifampicin resistance has been performed by a single, defined DNA restriction fragment carrying the genetic information for the beta subunit of E. coli RNA polymerase. In this transformation the transforming genetic character has been substituted for the corresponding recipient gene locus by recombination. The value of the described transformation system for locating genetic markers on DNA restriction fragments is discussed in comparison to previously reported in vitro systems.
Mol Gen Genet 1977 Oct 20
PMID:Transformation of Escherichia coli by a specific DNA restriction fragment. 33 30

The genome of virulent coliphage T5 contains about 30 sites which form stable complexes with E. coli RNA polymerase. Some of these sites bind RNA polymerase with high rates, others form extremely stable complexes as compared with promotors of other E. coli systems. The transcriptional activity of these promotors in vivo and in vitro reflects the rate of complex formation with RNA polymerase rather than the stability of the enzyme/promotor complex. The fastest, i.e. the most active promotors are found in the "early" region of gene expression followed by promotors of the "preearly" class. The few binding sites for the E. coli holoenzyme within the "late" region react more slowly with the enzyme.
Mol Gen Genet 1977 Dec 09
PMID:Interaction of E. coli RNA polymerase with promotors of coliphage T5: the rates of complex formation and decay and their correlation with in vitro and in vivo transcriptional activity. 34 Sep 27

The operon rpoB,C of Escherichia coli codes for the RNA polymerase subunits beta and beta'. rpoB procedes rpoC in the direction of transcription. The nearest characterised gene to rpoB on the chromosome is rplL, which codes for the ribosomal proteins L7/12. rplL appears to be transcribed in the same direction as rpoB,C, and it has been suggested that all three genes may lie in a single operon. The drug rifampicin induces increased production of beta and beta' in suitable strains of E. coli. We show here that alpha and sigma are also induced, whereas synthesis of L7/12 is not detectably affected.
Mol Gen Genet 1978 Mar 20
PMID:Non-coordinate expression of the neighbouring genes rplL and rpoB,C of Escherichia coli. 34 50

When transcription of the E. coli trp operon is blocked as a result of inhibition of ribosomal activities by chloramphenicol, nascent trp mRNA but not RNA polymerase molecules seem to detach from the template DNA. The continued association of RNA polymerase with DNA is inferred because RNA synthesis resumes at or near the sites of transcription blockage after removal of the antibiotic. When E. coli cells infected with lambdatrp phage are incubated with chloramphenicol under the "Ptrp-promoted" conditions (Imamoto and Tani, 1972; Segawa and Imamoto, 1974), the trp mRNA molecules synthesized after removal of the antibiotic contain only promoter-distal information. They are usually small in size, in spite of the fact that chloramphenicol inhibition does not lead to the degradation of trp mRNA. On the other hand, PL-promoted trp transcription, which is non-polar and insensitive to chloramphenicol action, does not show such a premature release of nascent trp mRNA in chloramphenicol-treated cells.
Mol Gen Genet 1978 Apr 25
PMID:Release of nascent trp mRNA from the operon DNA in chloramphenicol-treated cells of Escherichia coli. 35 98

Nucleoids were isolated from Escherichia coli B/r cells in steady-stage growth at different rates. The number of RNA chains growing on each nucleoid was estimated from the amount and size of RNAs synthesized by endogenous RNA polymerase. This figure represents the number of RNA polymerase molecules that are functioning in transcription and thus serves to indicate the frequency of transcription in the cells. With an increase in the growth rate from 0.27 to 1.73 (h-1), (a) the number of total RNA chains per genome increases from about 252 to 838, (b) the number of ribosomal RNA (rRNA) chains per genome increases as a function of the second power of the growth rate from about 19 to 255, and (c) the number of non-rRNA chains per genome increases linearly from about 233 to 538.
Mol Gen Genet 1978 Aug 04
PMID:Control of ribosomal RNA synthesis in Escherichia coli. IV. Frequency of transcription of ribosomal RNA genes as a function of growth rate. 36 39

A structural gene for sigma factor (rpoD) of DNA-dependent RNA polymerase (RNA nucleotidyltransferase; nucleoside-triphosphate: RNA nucleotidyltransferase, E.C. 2.7.7.6) was mapped precisely by a set of F' factors including those already published (Proc. Natl. Acad. Sci. USA. 74, 1831-1835 (1977)). Based on the result that rpoD is located at the dnaG-uxaAC region, a number of mutants containing a temperature-sensitive mutation at or near the uxaA gene were isolated by localized mutagenesis. One of these mutants was found to produce RNA polymerase altered in both thermostability and optimum salt concentration as a result of structural alteration of sigma factor. This mutation, U303, maps at 66 min on the genetic map of E. coli, near the dnaG locus, and affects normal growth of cells.
Mol Gen Genet 1978 Sep 20
PMID:RNA polymerase mutant with altered sigma factor in Escherichia coli. 36 59

Upon addition of excess one carbon metabolites (including serine)bacteria stop growing because of isoleucine starvation. After such treatment stringent bacteria rapidly resume normal growth whereas relaxed mutants remain unable for some time to grow. We show here that this is due to a lack of derepressibility of ilv genes after the starvation period. Results are also presented which show that RNA polymerase structural mutants may be selected among the clones resistant to a mixture of serine, methionine and glycine, in relA- strains. Finally circumstancial evidence suggests that the one carbon metabolism may be involved in a process controlling isoleucine metabolism.
Mol Gen Genet 1978 Sep 20
PMID:Correlation between the serine sensitivity and the derepressibility of the ilv genes in Escherichia coli relA- mutants. 36 63

The antibiotic rifampicin inhibits transcription initiation, but not the elongation and completion of nascent RNA transcripts. Addition of low concentrations of rifampicin only partially blocks initiation but at the same time specifically alters the general pattern of transcription in the culture. The transcription of genes specifying the beta and beta' subunits of RNA polymerase, and to a lesser extent of the genes specifying the RNA and protein components of the ribosome, was specifically stimulated relative to total transcription. In contrast, the transcription of the lactose operon was selectively reduced. These results are consistent with the ideas that the level of expression of the genes specifying the beta and beta' subunits is sensitive to the general rate of RNA synthesis in the culture, and that the expression of the beta and beta' RNA polymerase genes is related to the expression of ribosome component genes.
Mol Gen Genet 1978 Sep 20
PMID:Gene expression in Escherichia coli B/r during partial rifampicin-mediated restrictions of transcription initiation. 36 68

Oc mutations in the operators of bacteriophage lambda have been used to analyze the functional organization of the operators. In each operator, repressor binding sites 1 and 2, as identified biochemically, were found to be primarily responsible for the repressor affinity of the operators in vitro and for the repression of lytic functions in vivo. In addition, both sites were shown to be involved in the action of cro product at the operators. The data obtained have been used to estimate the repressor affinities of the individual binding sites. These affinities suggest that repressor bound at OR1 and OR2 interacts cooperatively. The results obtained support a model for repression of the early lambda operons where repressor bound at binding sites 1 and 2 interferes with RNA polymerase binding to the promotor sites.
Mol Gen Genet 1978 Oct 25
PMID:Mutational analysis of the operators of bacteriophage lambda. 36 70


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