Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

AraC protein from Escherichia coli has been further stabilized and characterized. pH is a critical variable in conferring stability. araC protein has a sedimentation coefficient of 4.0 +/- 0.2s on standardized 5%-20% glycerol gradients. Its isoelectric point is at a pH of 7.1.
Mol Gen Genet 1976 Apr 23
PMID:Stabilization and size of araC protein. 77 15

The hrp gene cluster of Pseudomonas solanacearum GMI1000 strain encodes functions that are essential for pathogenicity on tomato and for the elicitation of the hypersensitive response on tobacco. In this study, we present the nucleotide sequence of one of the hrp genes (hrpB) located at the left-hand end of the cluster and we show that hrpB encodes a positive regulator controlling the expression of hrp genes. hrpB has a coding capacity for a 477-amino-acid polypeptide, which shows significant similarity to several prokaryotic transcriptional activators including the AraC protein of Escherichia coli, the XylS protein of Pseudomonas putida and the VirF protein of Yersinia enterocolitica. The predicted hrpB gene product belongs to a family of bacterial regulators different from the previously described HrpS protein of the hrp gene cluster of Pseudomonas syringae pv. phaseolicola. Genetic evidence demonstrates that the hrpB gene product acts as a positive regulator of the expression in minimal medium of all but one of the putative transcription units of the hrp gene cluster and also controls the expression of genes located outside this cluster. We also show in this paper that the transcription of hrpB is induced in minimal medium and is partly autoregulated.
Mol Microbiol 1992 Oct
PMID:Evidence that the hrpB gene encodes a positive regulator of pathogenicity genes from Pseudomonas solanacearum. 147 94

DNA looping between the araO2 and araI sites holds the uninduced or basal level of expression of the araBAD genes from the pBAD promoter at a low level. Despite the presence of another and closer site potentially capable of mediating looping to araI, no repression from this site, called araO1, is observed. Here we show, using both in vivo and in vitro experiments, that the araO1 site is not normally occupied by AraC protein under repressing conditions, but that if AraC protein is overproduced and the araO2 site is absent, araO1 is then occupied and repression of pBAD can be observed.
J Mol Biol 1992 Mar 20
PMID:Repression of the araBAD promoter from araO1. 156 Apr 56

Evolution of complex regulatory pathways that control virulence factor expression in pathogenic bacteria indicates the importance to these organisms of being able to distinguish time and place. In the human intestinal pathogen Vibrio cholerae, control over many virulence genes identified to date is the responsibility of the ToxR protein. ToxR, in conjunction with a second regulatory protein called ToxS, directly activates the genes encoding the cholera toxin; other ToxR regulated genes are not activated directly by ToxR. For some of these genes, ToxR manifests its control through another activator called ToxT. Expression of toxT, which encodes a member of the AraC family of bacterial transcriptional activators, is ToxR dependent and is modulated by in vitro growth conditions that modulate expression of the ToxR virulence regulon. Thus, as in other regulatory circuits, co-ordinate expression of several genes in V. cholerae results from the activity of a cascading system of regulatory factors.
Mol Microbiol 1992 Feb
PMID:Co-ordinate expression of virulence genes by ToxR in Vibrio cholerae. 156 Jul 73

The arabinose operon promoter, pBAD, is negatively regulated in the absence of arabinose by AraC protein, which forms a DNA loop by binding to two sites separated by 210 base-pairs, araO2 and araI1. pBAD is also positively regulated by AraC-arabinose and the cyclic AMP receptor protein, CRP. We provide evidence that CRP breaks the araO2-araI1 repression loop in vitro. The ability of CRP to break the loop in vitro and to activate pBAD in vivo is dependent upon the orientation and distance of the CRP binding site relative to araI1. An insertion of one DNA helical turn, 11 base-pairs, between CRP and araI only partially inhibits CRP loop breaking and activation of pBAD, while an insertion of less than one DNA helical turn, 4 base-pairs, not only abolishes CRP activation and loop breaking, but actually causes CRP to stabilize the loop and increases the araO2-mediated repression of pBAD. Both integral and non-integral insertions of greater than one helical turn completely abolish CRP activation and loop breaking in vitro.
J Mol Biol 1991 Mar 05
PMID:AraC-DNA looping: orientation and distance-dependent loop breaking by the cyclic AMP receptor protein. 184 2

The anti-human immunodeficiency virus (-HIV) nucleoside analogs azidothymidine (AZT), dideoxycytidine (ddC), dideoxyinosine (ddl), dideoxydidehydrothymidine (D4T), and dideoxydidehydrocytidine (D4C) and the anticancer drug cytosine arabinoside (AraC) were compared for their effects on the mitochondrial DNA (mtDNA) content in a human lymphoblastoid cell line, CEM. The potency of these compounds in reducing mtDNA content was in the order of ddC greater than D4C greater than D4T greater than AZT greater than ddl. AraC did not have a significant effect on mtDNA content. All of the compounds tested, except AraC, stimulated lactic acid production at concentrations that inhibited mtDNA synthesis. The action of ddC and ddl occurred at concentrations that did not affect cell growth significantly in 4 days but retarded cell growth by day 6. D4T and D4C decreased mtDNA content by 50% at doses lower than those that inhibited cell growth by 50% in 4 days (ID50). However, AZT required a dose higher than the ID50 to exert similar effects on mtDNA content. The decrease of mtDNA content caused by ddC also occurred in nerve growth factor-treated PC12 cells, which differentiate to neuron-like cells upon treatment with nerve growth factor. The preferential inhibition of mtDNA, compared with cell growth, by some of these anti-HIV nucleoside analogs correlates well with their ability to cause drug-limiting delayed toxicity, such as peripheral neuropathy, in patients. These data suggest that the selective mitochondrial toxicity could be responsible for the delayed toxicity caused by these anti-HIV analogs.
Mol Pharmacol 1991 May
PMID:Effect of anti-human immunodeficiency virus nucleoside analogs on mitochondrial DNA and its implication for delayed toxicity. 185 60

Expression of the 987P gene cluster is activated by the adjacent IS1 element of an STpa transposon. Nucleotide sequence analysis of the 987P-DNA region contiguous with this IS1 element revealed the presence of an open reading frame designated fapR, encoding a basic protein of 260 amino acid residues with a molecular mass of 30,349 Daltons. The gene product, FapR, possesses similarity to a number of positive regulators of gene expression: VirF, Rns, AppY and EnvY. Moreover, a 43-amino-acid residue sequence in the C-terminal part of FapR is similar to the C-terminal domain of AraC, RhaR, and RhaS. Expression of fapR is dependent on the adjacent IS1 element. The FapR protein appears to be required for activation of the silent promoter of the fimbrial subunit gene, fapC.
Mol Microbiol 1990 Oct
PMID:Characterization of FapR, a positive regulator of expression of the 987P operon in enterotoxigenic Escherichia coli. 207 60

The identities of two cloned, arabinose-inducible promoters were tested by hybridizing promoter DNA fragments with restriction digests of chromosomal DNA containing Mudlac phage inserted in either araFGH or in araE transport operons. One promoter, thought to be araE, is within 10(3) base-pairs of a Mudlac insertion in the araE gene. The second promoter was not found within several thousand base-pairs of either of the known transport genes. This promoter is now named araPJ (araJ). The DNA sequence of the fragment containing the araFGH promoter was determined. The start site of transcription in vivo was located to within +/- 1 base-pair (bp) by S1 nuclease mapping. DNase 1 footprinting revealed that, in comparison with the araBAD and araE promoters, the locations of the AraC and cyclic AMP receptor protein (CRP) binding sites are reversed with CRP lying between AraC and RNA polymerase. The central location of the CRP binding site may explain why the araFGH promoter is more catabolite sensitive than the other ara promoters. AraC and CRP were both required for maximal transcription in vitro, although a low level of transcription was detected with CRP alone. S1 nuclease mapping of mRNA-DNA hybrids from the araJ promoter located the transcription start point to within #/- 3 bp, and demonstrates that the promoter is dependent upon AraC protein and CRP in vivo. DNase footprinting showed that the location of the AraC protein binding site on araJ is adjacent to the RNA polymerase site, as seen at the araBAD and araE promoters. Two CRP sites were observed; one is upstream from the AraC site and one is downstream from the transcription start site.
J Mol Biol 1990 Oct 20
PMID:Characterization of the Escherichia coli araFGH and araJ promoters. 223 17

This study reports a genetic analysis of the interactions between a positive regulator of gene expression and its effector molecules. Transcription of the TOL plasmid meta-cleavage pathway operon is specifically stimulated by the XylS protein positive regulator either through activation of this regulator by benzoate effectors or through its hyperproduction. One xylS mutant that exhibits constitutive expression of the operon promoter has been characterized, together with six mutants encoding altered XylS proteins that recognize as effectors benzoate analogues that are non-effectors for the XylS wild-type protein. The changes in two mutant regulators are located at the N-terminal end of the protein, within a putative beta-pleated domain. These mutant proteins exhibit a markedly increased affinity for normal benzoate effectors, with K's values fivefold to 60-fold lower than those of the wild-type XylS protein. They are additionally activated by new effectors having certain substituents at position 2, 3 and 4 of the aromatic ring. Two other mutant proteins recognize new effectors having substituents at position 4 and 5 of the aromatic ring, and contain mutations at their C-terminal end within a putative alpha-helix-rich domain. Three other mutations, one of which leads to constitutive expression from Pm, each result in an amino acid change in the central region of the regulator. These findings suggest but do not prove that the effector binding pocket of the XylS protein may be composed of two or more non-contiguous segments of its primary structure. The XylS protein exhibits homology with the AraC protein of Escherichia coli, a protein that stimulates transcription from ara promoters when it is activated by arabinose or benzoate. Mutations influencing effector activation of the XylS protein characterized in this study are all located in regions exhibiting a high degree of homology with the corresponding aligned sequence of AraC protein.
J Mol Biol 1990 Jan 20
PMID:Signal-regulator interactions. Genetic analysis of the effector binding site of xylS, the benzoate-activated positive regulator of Pseudomonas TOL plasmid meta-cleavage pathway operon. 240 53

Depurination/depyrimidation binding-interference experiments (missing contact probing) identified specific candidate residue-base interactions lost by mutants of Escherichia coli L-arabinose operon regulatory protein, AraC, to one of its binding sites, araI. These candidates were then checked more rigorously by comparing the affinities of wild-type and alanine-substituted AraC protein to variants of araI with alterations in the candidate contacted positions. Residues 208 and 212 apparently contact DNA and support, but do not prove the existence of a helix-turn-helix structure in this region of AraC protein whereas contacts by mutants with alterations at positions 256, 257 and 261 which are within another potential helix-turn-helix region do not support the existence of such a structure there. The missing contacts displayed by three AraC mutants are found within two major groove regions of the DNA and are spaced 21 base-pairs apart in a pattern indicating a direct repeat orientation for the subunits of AraC.
J Mol Biol 1989 Oct 20
PMID:Determining residue-base interactions between AraC protein and araI DNA. 253 Dec 26


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