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

The recA gene of Pseudomonas aeruginosa has been isolated and its nucleotide sequence has been determined. The coding region of the recA gene has 1038 bp specifying 346 amino acids. The recA protein of P. aeruginosa showed a striking homology with that of Escherichia coli except for the carboxy-terminal region both at the nucleotide and amino acid level. The recA+-carrying plasmids restored the UV sensitivity and recombination ability of several rec mutants of P. aeruginosa. The precise location of the recA gene on the chromosome was deduced from the analysis of R' plasmids.
Mol Gen Genet 1987 Jul
PMID:The sequence and function of the recA gene and its protein in Pseudomonas aeruginosa PAO. 282 59

Plasmidic recombination in E. coli K12 has been previously demonstrated to be dependent on the host rec genotype. The construction of plasmids that carry a duplication within an antibiotic-resistance gene is described. Recombination between the direct repeats recreates an active antibiotic-resistance gene, allowing quantitative analysis of recombination frequencies in a closely related set of E. coli K12 strains carrying various rec mutations. Using this system, intraplasmidic recombination of a duplication within the pBR322 tetracycline-resistance gene is shown to be rec-dependent while recombination of a similar duplication within the kanamycin-resistance gene of Tn903 is shown to be independent of recA, recB, recC, recE, recF and sbcB.
Mol Gen Genet 1985
PMID:Rec-dependent and Rec-independent recombination of plasmid-borne duplications in Escherichia coli K12. 299

The deletions in tandem prophage lambda appear with high frequency (to 10%) in rec A- strain of Escherichia coli. The deletions were shown by marker rescue and hybridization of fragments of DNA on nitrocellulose filters with nick-translated phage lambda DNA localized only in prophage area. Right and left att sites are not involved. The majority of defective lysogens had all regulatory regions and deletions of late structural genes. These strains may be used for construction of the host-vector systems with the strongest promoter p'R of phage lambda.
Mol Biol (Mosk)
PMID:[Deletion of late genes of the prophage lambda]. 300 8

Broad host range IncP-1 plasmids are able to integrate into the chromosome of gram-negative bacteria. Strains carrying an integrated plasmid can be obtained when the markers of a temperature-sensitive (ts) plasmid derivative are selected at non-permissive temperature; in this way Hfr (high frequency) donor strains can be formed. The integrated plasmids, however, tend to be unstable in the absence of continuous selective pressure. In order to obtain stable Hfr donor strains of Pseudomonas aeruginosa PAO, we constructed a derivative of an RP1 (ts) plasmid, pME134, which was defective in the resolvase gene (tnpR) of transposon Tn801. Chromosomal integration of pME134 was selected in a recombination-deficient (rec-102) PAO strain at 43 degrees C. Plasmid integration occurred at different sites resulting in a useful set of Hfr strains that transferred chromosomal markers unidirectionally. The tnpR and rec-102 mutations prevented plasmid excision from the chromosome. In several (but not all) Hfr strains that grew well and retained the integrated plasmid at temperatures below 43 degrees C, the insertion element IS21 of RP1 was found to be inserted into the trfA locus (specifying an essential trans-acting replication function) of the integrated plasmid. One such Hfr strain was rendered rec+; from its chromosome the pME134::IS21 plasmid (= pME14) was excised and transferred by conjugation to Escherichia coli where pME14 could replicate autonomously only when a helper plasmid provided the trfA+ function in trans. Thus, it appears that trfA inactivation favours the stability of chromosomally integrated RP1 in P. aeruginosa.
Mol Gen Genet 1986 Jun
PMID:IS21 insertion in the trfA replication control gene of chromosomally integrated plasmid RP1: a property of stable Pseudomonas aeruginosa Hfr strains. 301 34

Tn2555, a new transposon coding for genes of sucrose utilization was studied. Tn2555 was shown to integrate into the plasmids RP4 and R6K, phage P1CmClr100 and Escherichia coli K12 chromosome. Tn2555 frequency of transposition to RP4 and R6K DNA is (2-5) X 10(-7) in Rec+-strain, (3-6) X 10(-8) in Rec--strain. Tn2555 integration site in phage P1CmClr100 Sac+-derivative studied has been localised within the C-segment of P1 DNA. In three independent cases of Tn2555 transposition to the chromosome the transposon was found to be integrated in the region between 29 and 32 min of Escherichia coli K12 linkage map. The restriction endonuclease analysis of seven independent isolates of RP4::Tn2555 has shown the grouping of Tn2555 integration sites in the Tn1 region of RP4. Frequent rearrangements occurring within Tn2555 have been revealed by the analysis. However, an invertible DNA segment of about 6-7 kb was preserved in all transposon structures.
Mol Gen Mikrobiol Virusol 1987 Jun
PMID:[Properties of transposon Tn2555 carrying the genes for sucrose utilization]. 304 Dec 2

An isogenic set of 11 recombination-deficient mutant strains of Bacillus subtilis has been constructed. Whereas plasmid pUB110 is stably maintained in such Rec- cells, the high copy number plasmid pC194 is unstable. Instability in Rec- strains could be mostly attributed to the deleterious effect of the presence of the plasmid on the Rec- cells' growth capability. In part, instability of pC194 derivatives could also be correlated with the presence of an unusually high amount of multimeric DNA molecules.
Mol Gen Genet 1987 Jun
PMID:Plasmid maintenance in Bacillus subtilis recombination-deficient mutants. 311 24

The recombinant vector plasmids were constructed having the DNA of pUB110 plasmid (4,5 kb, KmR) from Staphylococcus aureus inserted into the cryptic plasmids pANS (8 Kb) and pANL (48,5 kb) of cyanobacterium Anacystis nidulans R2. The hybrid plasmids transform cyanobacterial cells to Km-resistance with high efficiency. The plasmid pBS20, containing the complete sequence of pANS and pUB110 DNA, transforms Bacillus subtilis rec E4 protoplasts being, however, unstable in bacilli cells and disintegrates deriving a parent pUB110 plasmid.
Mol Gen Mikrobiol Virusol 1988 Jan
PMID:[Hybrid vectors for the cyanobacterium Anacystis nidulans R2, containing the plasmid pUB110 from Staphylococcus aureus]. 312 33

This report puts into perspective a series of exploratory statistical analyses carried out on the major genotoxicity data bases. While large compilations of data, even though computerized, suffer from their own size and are quite intractable to scientific reflection and judgement, the multivariate data analysis methods used by us are specifically designed for reorganising the information in a rational way and highlighting the underlying regularities of the data. The analyses reported here refer to the following data bases: the International Program for the Evaluation of Short-Term Tests for Carcinogens, the International Program on Chemical Safety Collaborative Study on In Vitro Assays, the Gene-Tox data base, and a subset of the U.S. National Toxicology Program data. Although the various data bases consisted of different sets of chemicals and had different underlying rationales, a number of invariant associations among short-term test performances were highlighted. The overall evidence indicated that the traditional classification of assays (according to the criteria of genetic end-point and phylogenetic position of the assays) was in contrast with the actual, operational similarities among assay performances, in that the experimental responses of the tests to the large variety of chemicals under consideration pointed to an alternative classification scheme. This consisted of three major classes: 1) a class comprising the in vivo assays; 2) a class grouping together many of the most widely used in vitro assays (Salmonella, chromosomal aberrations, and sister chromatid exchanges in Chinese hamster ovary cells, the various mutation tests in mammalian cell systems, etc.); 3) a second in vitro assay class (with Syrian hamster embryo cell transformation, Saccharomyces cerevisiae XV185-14C, B. subtilis rec-, Escherichia coli pol A). Such classes had clearly differentiated features with respect to carcinogenicity prediction. The implications of these findings for the current debate on mutagenicity testing are discussed.
Environ Mol Mutagen 1988
PMID:Statistical exploration of four major genotoxicity data bases: an overview. 338 41

A recombination-deficient (Rec-) strain of Caulobacter crescentus has been isolated from a collection of mutants sensitive to ultraviolet irradiation. The Rec- mutant fails to give recombinants following phi Cr30-mediated generalized transduction or following RP4-mediated conjugation. The recombination frequency in the Rec- strain is at least 5000-fold lower than in the wild type strains. The Rec- mutant is indistinguishable from wild type in terms of morphology, growth rate, viability, and phage sensitivities, differing only in properties known to be associated with recA-type mutations in other organisms: recombination frequency, ultraviolet sensitivity, and Weigle reactivation. The map location of the rec-526 allele has not been identified, but rec-526 can be cotransferred with the fla-169 mutation by RP4-mediated conjugation at low frequency. This apparent linkage has been used to move the rec mutation to other strains. The Rec- mutant resembles recA strains of other organisms and provides a healthy strain severely deficient in recombination for use in complementation and cloning studies involving C. crescentus.
Mol Gen Genet 1985
PMID:Recombination deficient mutant of Caulobacter crescentus. 385 26

In Schizosaccharomyces pombe, a suppressor-active mutation at the anticodon site of the tRNASerUCA gene sup3 leads to opal (UGA)-specific suppression. Second-site mutations (rX) in sup3 inactivate the suppressor. The sup3-UGA, rX double mutants are genetically unstable in meiotic selfings, due to the intergenic transfer of information between sup3 and the unlinked genes sup9 and sup12 (Hofer et al. 1979; Munz and Leupold 1981; Munz et al. 1982). These three genes have considerable sequence homology over about 200 base pairs (Hottinger et al. 1982). Mutants showing a decrease or an increase of the meiotic instability at sup3 have been selected. One mutation (rec3-8) increases both the genetic instability and the frequency of intragenic recombination in sup3 by one order of magnitude. It has no effect on the stability of the nonsense alleles arg1-230 (UAA), ade6-704 and ural1-61 (UGA) or on the frequency of crossing-over between sup3 and the closely linked gene cdc8. The existence of a common genetic control over intragenic recombination and genetic instability at sup3 provides a direct way of selecting for rec mutants in homothallic haploid strains of S. pombe carrying a suppressor-inactive allele of sup3. It also supports the hypothesis that the instability of mutant alleles of this gene is due to chromosome mispairing at meiosis allowing sup3 to pair with sup9 or sup12 and then to undergo recombination by gene conversion restoring the suppressor-active allele sup3-UGA from the suppressor-inactive allele sup3-UGA, rX.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Gen Genet 1985
PMID:Direct selection of mutants influencing gene conversion in the yeast Schizosaccharomyces pombe. 386 28


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