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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of colicin genes is controlled by the SOS-system (Lex A repressor) and the adenylate-cyclase system (cAMP-CAP complex). The effect of plasmid DNA supercoiling on the expression of the operons of colicins E1, E2, and E3 has been studied by using E. coli minicells. It has been shown for the colicin E1 operon that it is the promoter that is influenced by supercoiling: an increase in negative supercoiling elevates the expression and, vice versa, DNA relaxation reduces the expression. The effect of supercoiling on gene activity of the colicin E1 immunity protein has not been observed, which may be due to the specific orientation of this gene. With the two other colicins supercoiling affects the expression of all genes which constitute the operon. The regulation of the colicin operon expression has been confirmed to occur at three levels: by the LexA protein, by the cAMP-CAP complex, and by the plasmid DNA supercoiling.
Mol Biol (Mosk)
PMID:[The effect of supercoiling of DNA from colicinogenic plasmids on the expression of col, imm and lys genes]. 269 78

The binding of the cyclic adenosine 3',5' monophosphate receptor protein (CRP or CAP) of Escherichia coli to non-specific DNA and to a specific lac recognition sequence has been investigated by circular dichroism (c.d.) spectroscopy. The effect of cAMP and cGMP on the co-operative non-specific binding was also studied. For the non-specific binding in the absence of cAMP a c.d. change (decrease of the intensity of the positive band with a shift of its maximum to longer wavelength) indicates that the DNA undergoes a conformational change upon CRP binding. This change might reflect the formation of the solenoidal coil previously observed by electron microscopy. The amplitude of the c.d. change increases linearly with the degree of saturation of the DNA and does not depend on the size of the clusters of CRP bound. From the variation of the c.d. effect as a function of the ionic strength, the product K omega (K, the intrinsic binding constant and omega, the co-operativity parameter) could be determined. The number of ion pairs involved in complex formation between CRP and DNA was found to be six to seven. Experiments performed with several DNAs, including the alternating polymers poly[d(A-T)] and poly[d(G-C)], demonstrated that the conformational change does not depend on the DNA sequence. However, in the presence of cAMP the c.d. spectrum of the DNA shows only a small variation upon binding CRP. In contrast, in the presence of cGMP the conformational change of the DNA is similar to that observed when non-liganded CRP binds. For the specific lac operon binding, the c.d. change is different from those observed for non-specific binding in the presence or absence of cAMP. These results emphasize the high variability of the DNA structure upon binding the same protein.
J Mol Biol 1987 May 05
PMID:Interaction between the cyclic AMP receptor protein and DNA. Conformational studies. 282 Dec 69

We have isolated a new class of mutations in rpoD, the gene encoding the sigma 70 subunit of Escherichia coli RNA polymerase, that alter the transcription initiation properties of RNA polymerase holoenzyme. The rpoD(Lac) mutations increase expression of the lac operon in the absence of CAP-cAMP, allowing a strain lacking adenyl cyclase to grow on lactose. Four of the six alleles isolated have three- to fivefold increases in the amount of lac mRNA and beta-galactosidase per cell. We show that these four mutations increase transcription initiation from the same promoter used by wild-type RNA polymerase. The mutations were mapped and sequenced. One mutation occurs in the codon for amino acid 389 of the sigma 70 polypeptide. The remaining five mutations are clustered, affecting residues 570, 571 and 575. These five mutations are within or near a proposed helix-turn-helix motif in the C terminus of sigma 70.
J Mol Biol 1988 Sep 05
PMID:Mutations in rpoD, the gene encoding the sigma 70 subunit of Escherichia coli RNA polymerase, that increase expression of the lac operon in the absence of CAP-cAMP. 284 53

A human transient expression system was used to measure the influence of simian virus 40 T antigen and adenovirus E1a proteins on the activation of alpha interferon subtype 1 (IFN-alpha 1) and IFN-beta promoters linked to the reporter chloramphenicol acetyltransferase gene. Large T-antigen production, amplified by expression plasmid replication in transfected 293 cells, was able to trans activate the IFN-beta promoter 5- to 10-fold, increasing both the constitutive and Sendai virus-induced levels of expression. Surprisingly, the previously quiescent transfected IFN-alpha 1 promoter in T-antigen-expressing cells displayed a level of inducibility similar to IFN-beta. The endogenous IFN-alpha 1 gene was also inducible to a limited extent in cells expressing T antigen. A truncated IFN-beta promoter deleted to position -37 relative to the CAP site was neither inducible nor trans activated by T antigen, suggesting that sequences required for efficient induction were also needed for trans activation. Since 293 cells express adenoviral E1a proteins, experiments were also performed in HeLa cells to assess the relative contribution of T antigen and E1a proteins to IFN trans activation. In HeLa cells, T-antigen coexpression increased the constitutive level of IFN-beta and IFN-alpha 1 promoter activity without augmenting relative inducibility. Coexpression of T antigen and E1a proteins did not have a cooperative effect on type 1 IFN expression.
Mol Cell Biol 1988 Aug
PMID:trans activation of type 1 interferon promoters by simian virus 40 T antigen. 285 Apr 92

Digestion of canine and bovine intercalated disks with a calcium-activated protease (CAF) removes the electron-dense material similar to that found at the Z-line and presumably consisting primarily of alpha-actinin. The major filaments exposed by CAF are actin, and the polarity is away from the intercalated disk, as was confirmed by decoration with heavy meromyosin. The length of actin filaments associated with the fascia adherens region at the concave region is 1.2- to 2.2-fold that of actin filaments (I-filaments) in the sarcomere and varies depending on the interdigitation of the membrane at the cell junction. Actin filaments at the intercalated disk seem to be attached (or very close) to the membrane in a direct, rather than looping, manner.
J Ultrastruct Mol Struct Res 1988 Sep
PMID:Polarity and length of actin filaments at the fascia adherens of the cardiac intercalated disk. 285 47

The Escherichia coli lac promoter has been shown to contain an RNA polymerase binding site (P2) that overlaps with, and is shifted 22 base-pairs upstream from the normal lac promoter (P1). In this paper, we provide RNA polymerase protection data obtained in vitro that show that, in the absence of CAP-cAMP, in vitro P2 is the preferred polymerase binding site on the P+ template. In the presence of CAP-cAMP, polymerase binding to P2 is reduced and more polymerase is bound at P1. Two lac P1 "-35 region" mutations, L157 and 4, which increase the homology between this region and the consensus "-10 region" sequence, are both shown to have an increased affinity for polymerase binding at P2. CAP-cAMP is also able to decrease the amount of polymerase bound to P2 and to increase the amount bound to P1 on these mutant promoter fragments. P2 does not initiate transcription efficiently in vivo. Nuclease S1 mapping experiments detect only a low level of transcription from one of the P2 "up" mutations, but no beta-galactosidase synthesis is directed by this mutant. Mutations such as L157 and 4, which alter the P2-10 region, also alter lac P sensitivity to CAP-cAMP in vivo, suggesting that the P2 sequence plays a role in CAP-cAMP regulation of lac P. Possible roles for P2 in vivo are discussed.
J Mol Biol 1985 Oct 05
PMID:Properties of lac P2 in vivo and in vitro. An overlapping RNA polymerase binding site within the lactose promoter. 299 53

Kline et al. (1980) have reported that indole-3-acetic acid (IAA) and four other indole derivatives are able to substitute for cAMP in activating expression of the ara regulon of E. coli. We have examined this phenomenon in detail, utilizing fusions between the structural gene for beta-galactosidase and the promoters for the araBAD, araE, and araFG operons. We confirm that IAA potently stimulates transcription from the araBAD promoter. The effect is highly specific to araBAD, as IAA has no, or only slight, effects on the araE and araFG operons. However, contrary to the results of Kline et al., we find that the action of IAA does not require CAP. Thus, IAA fully stimulates the transcription of araBAD in a strain which bears a complete deletion of the crp gene.
Mol Gen Genet 1985
PMID:The catabolite gene activator protein (CAP) is not required for indole-3-acetic acid to activate transcription of the araBAD operon of Escherichia coli K-12. 299 82

The biodegradative threonine dehydratase gene (tdc) of Escherichia coli was cloned by isolating a dehydratase negative mutant after Tn5 mutagenesis, cloning the tdc::Tn5 DNA into pBR322 and then replacing the Tn5 element on the plasmid in vivo. Subcloning and nucleotide sequence data revealed two distinct procaryotic promoter-like elements each containing a potential CAP-binding site and AT-rich regions, and a Shine-Dalgarno sequence. One of these putative promoters, P2, was located immediately upstream from the tdc coding region, and a second, P1, was approximately 1 kilobase upstream from P2. Deletion of the potential CAP-binding site from P1 prevented tdc gene expression. However, removal of P2 and a large segment of the upstream DNA had no discernible effect on dehydratase synthesis. A 936-base pair open reading frame was found between P1 and the tdc coding region, which produced a polypeptide of about 32 kilodaltons. The data suggest that P1, and not P2, is necessary for tdc gene expression, and that the DNA sequences coding for the 32 KD polypeptide and threonine dehydratase are part of a single transcriptional unit.
Mol Gen Genet 1985
PMID:Molecular cloning and expression of the biodegradative threonine dehydratase gene (tdc) of Escherichia coli K12. 300 33

A soybean gene (Gmhsp17.5-E) encoding a small heat shock protein was introduced into primary sunflower tumors via T-DNA-mediated transformation. RNA blot hybridizations and S1-nuclease hybrid protection studies indicated that the heat shock gene containing 3.25 kilobases of 5'-flanking sequences was strongly transcribed in a thermoinducible (40 degrees C) manner. Transcriptional induction also occurred to a lesser extent upon treatment of whole tumors with sodium arsenite and CdCl2. Basal (26 degrees C) transcription was not detected in soybean seedlings, but it was quite evident in transformed tumor tissue. A 5' deletion to -1,175 base pairs with respect to the CAP site had no effect on the levels of thermoinducible transcription, but it resulted in a large increase in basal transcription. Further removal of DNA sequences (including the TATA-distal heat shock consensus element) to -95 base pairs reduced thermoinducible transcription by 95% and also greatly decreased basal transcription. The termini of the Gmhsp17.5-E RNA in the tumor were generally the same as those present in soybean RNA, with the exception of several additional 3' termini.
Mol Cell Biol 1986 Feb
PMID:Upstream sequences required for efficient expression of a soybean heat shock gene. 302 55

The sigma subunits of eubacterial RNA polymerases determine the site selectivity of initiation of transcription at promoters. Mutations in rpoD, the gene that encodes sigma 70, the major sigma factor in Escherichia coli, should be useful in determining the molecular details of the process of transcription initiation. However, such mutations are likely to be deleterious or lethal, since sigma70 is an essential gene product. We designed a system for the rapid isolation and fine structure mapping of mutations in rpoD, which allows selection of mutations that would otherwise be deleterious to the cell. We used this system to isolate a new class of mutations in rpoD, mutations that relieve the requirement for CAP-cAMP for initiation at promoters in the mal regulon. These mutations, which we designate rpoD(Mal) mutations, occur in two clusters in the rpoD gene within regions previously suggested by amino acid sequence comparisons to be important for sigma structure or function. We cannot distinguish whether the rpoD(Mal) mutations affect mal expression by altering interaction between RNA polymerase and mal promoters or between RNA polymerase and the accessory transcription factor MalT. However, the effects of the mutations on activator-independent transcription from the lac promoter (4 rpoD(Mal) mutations decrease CAP-independent expression of the lac promoter in vivo) suggest that the regions of sigma identified by our mutations may be directly involved in promoter recognition.
J Mol Biol 1988 Sep 05
PMID:Mutations in rpoD that increase expression of genes in the mal regulon of Escherichia coli K-12. 305 19


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