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Query: UNIPROT:P06889 (Mol)
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Hybrid plasmids were constructed from fragments of F'ara episomes formed by the restriction endonuclease EcoRI and a linear form of the plasmid ColE1 created by cleavage with EcoRI. Hybrid plasmids were constructed containing the entire ara region or the ara region with various parts deleted. E. coli K12 host strains were constructed which contained different deletions of the ara region. The hybrid plasmids were transferred to those strains whose ara deletion complemented that of the plasmid. The initial differential rates of synthesis of L-arabinose isomerase, the product of the araA gene, were determined for the Ara+, plasmid containing strains. These studies demonstrated that strains containing delta(araOIBA)718 produce elevated levels of araC protein, suggesting the araC promoter has been altered by this deletion. Evidence is also presented which suggests that araC protein activates the ara-BAD operon to higher levels when it is present in cis rather than trans. Amplification of the products of the cloned genes is observed when compared to haploid levels in some cases.
Mol Gen Genet 1979 Jun 20
PMID:Regulation of the L-arabinose operon in strains of Escherichia coli containing ColE1-ara hybrid plasmids. 38 53

A segment of DNA located in the region of the E. coli K12 chromosome previously identified by the Rac phenotype can function as a self-replicating plasmid. Evidence is presented that this plasmid, the oriJ plasmid, contains the origin of replication of a defective prophage postulated to be located in this chromosomal region by Low (1973). The plasmid can only be maintained in strains in which this postulated prophage has been deleted. In strains which possess the prophage selection for plasmid maintenance permits the isolation of clones containing new deletions which we postulate are the result of prophage excision.
Mol Gen Genet 1979 Sep
PMID:Location and characterisation of a new replication origin in the E. coli K12 chromosome. 39 Mar 12

We confirm the hypothesis of Low (1973) that many E. coli K12 strains contain a prophage (the Rac prophage) located a few minutes clockwise of the trp operon on the genetic map. We have used restriction endonucleases and 32P-labelled probes to construct a physical map of this prophage. Some E. coli K12 strains, including AB1157, have lost the entire prophage, apparently by a specific deletion. This is consistent with prophage excision by site-specific recombination. lambda reverse (lambda rev) phages (Zissler et al., 1971) are recombination proficient derivatives of phage lambda in which the phage recombination functions have been replaced by analogous functions (RecE) derived from the host chromosome (Gottesman et al., 1974; Gillen et al., 1977). Our data support the origin of lambda rev plages by recombination between lambda and the Rac prophage following excision of the Rac prophage from the E. coli chromosome. Important experimental data are included in the Figure legends.
Mol Gen Genet 1979 Sep
PMID:Physical characterisation of the "Rac prophage" in E. coli K12. 39 Mar 13

Synthesis of DNA complementary to the transferred strand of an IncI alpha plasmid has been shown previously to require DNA polymerase III. The possible involvement of the two defined priming proteins of Escherichia coli K12, RNA polymerase and primase, in initiating this conjugal DNA synthesis had been examined. Primase was inactivated using temperature-sensitive dnaG3 mutants and RNA polymerase was inhibited using rifampicin. When these two proteins were simultaneously inactivated in both parental strains, the average recipient synthesised at least one single-stranded equivalent of R144drd-3 before the rifampicin-treated donors lost the ability to transmit DNA. It is proposed that the product of a plasmid transfer gene is responsible for initiating this DNA synthesis in recipients. The results imply that this protein is supplied by the donors.
Mol Gen Genet 1979 Oct 01
PMID:A novel priming system for conjugal synthesis of an IncI alpha plasmid in recipients. 39 29

Three mutations caused by the integration of IS4 in galT in both possible orientations were shown by DNA sequence analysis to be integrated between a duplication of eleven base pairs of gene galT. IS4 has been cloned from its single position on the E. coli K12 chromosome. Here, 12 base pairs are duplicated adjacent to IS4. This sequence is unrelated to the duplicated sequence in galT.
Mol Gen Genet 1979 Oct 01
PMID:IS4 is found between eleven or twelve base pair duplications. 39 35

DNA fragments of phage PM2 restricted with Hin dIII endonuclease was cloned in the vector pBR 322 in an Escherichia coli K12 host. The attempt to clone full length PM2 DNA restricted with PstI endonuclease has been unsuccesful. From six randomly chosen recombinant clones DNA was purified and analysed with EcoRI, PstI and Hin dIII endonucleases. The physical map of three chimeric plasmids was unequivocally established. It was shown, that the whole PM2 genome was cloned, although in separate fragments. However, most of the recombinant clones were instable in the absence of selective pressure.
Mol Gen Genet 1979 Nov
PMID:Cloning of bacteriophage PM2 DNA in Escherichia coli K12. 39 43

As an effort to elucidate the control of quality and quantity of the DNA-dependent RNA polymerase in Escherichia coli, the rate of synthesis of the individual subunits was determined during shift-up and -down of nutrients. When the strain B/r grown in a succinate medium was imposed to a shift-up by adding a mixture of glucose and amino acids, rapid rise was observed of the differential rates of the synthesis of alpha, beta and beta' subunits, the constituents of core enzyme, leading to the increase of core polymerase concentration. The differential rates decreased thereafter to the level characteristic of the post-shift rate of cell growth. Compared to the strain B/r, the adaptation was slow in the strain K12 W3350. On the other hand, upon transfer of the strain B/r from a glucose-amino acids medium to a glucose medium lacking amino acids, the differential rate of core polymerase synthesis decreased rapidly and then regained the rate characteristic of the new growth rate. Similar control was also observed on the rate of ribosomal protein synthesis suggesting the coordinate expression of genes for the core polymerase subunits and ribosomal proteins. Thus, the intracellular concentration of RNA polymerase as well as of ribosomes might be one of the most important factors that affect the rate of bacterial growth. The rate of alpha subunit synthesis, however, exhibited little change during the shift-up but a considerable decrease was observed during the shift-down.
Mol Gen Genet 1975 Dec 23
PMID:Biosynthesis of RNA polymerase in Escherichia coli. II. control of RNA polymerase synthesis during nutritional shift up and down. 76 37

Studies on the rate of synthesis of the beta and beta' subunits of RNA polymerase in haploid strains of Escherichia coli K12 containing poorly-suppressed rif degrees am mutations provide conclusive evidence that synthesis of at least these two subunits is regulated.
Mol Gen Genet 1975 Dec 30
PMID:Induction of RNA polymerase synthesis in Escherichia coli. 76 46

Transducing lambda bacteriophages have been isolated which carry the divergently transcribed argECBH operon of E. coli K12 and various portions of the adjacent ppc and bfe chromosomal regions. They were recovered from lysates prepared by the procedure of Schrenk and Weisberg using a Ppc+ Arg+ Bfe+ strain carrying a deletion of the usual attachment site of lambda. Heteroduplex DNA mapping of these lumbdadarg and of the phi 80 darg isolated by B. Konrad indicates that the two kinds of phages carry the arg cluster in opposite orientations, a situation favorable for the isolation of argECBH DNA. A physical map of the ppc argECBH bfe region including 2 unusual attachment sites of lambda has been constructed. The localization of the end points of certain arg deletions provides a useful reference framework for the currently pursued mapping of mutations affecting the control of divergent transcription and for the location of restriction enzyme cleavage sites in the arg region.
Mol Gen Genet 1976 Jan 16
PMID:Isolation and characterization of lambdadargECBH transducing phages and heteroduplex analysis of the argECBH cluster. 76 53

Taking advantage of the Spi (sensitivity to P2 interference) phenomenon, bacterial mutants seemingly resistant to phage lambdasusNnin5, but sensitive to phage lambdaspi, were isolated from a strain of E. coli K12 carrying no nonsense suppressor and lysogenic for P2. A class of these mutants, designated nitA (N-independent transcription), is described here. Upon infection of the nitA mutants with a trp transducing phage lambdasusN7N53ptrp46 which carries the E. coli trpE and D genes in the CIII-att region of the lambda genome, formation of anthranilate synthetase (ASase, a complex protein of trp E and D gene products) was clearly demonstrated. In contrast, no ASase formation was observed in the parent nitA+ strain under the same conditions. The synthesis is subject to "turn off" control, and is completely repressed by the CI repressor of phage lambda. The nitA cells lysogenic for lambdaCI857susN7N53 are killed by thermal induction much more efficiently than the parent cells lysogenic for the same phage. The nitA mutants support the growth of lambdasusN7N53byp much better than the parent. These results suggest that the nitA mutation permits the early leftward and rightward transcription of the lambda genome in the absence of the N gene product. On the E. coli genetic map, nitA is located between ilv and metE, nearer to ilv. The mutant allele is recessive to the wild-type allele. The present evidence, together with results of biochemical investigations to be reported, suggests that nitA is a gene specifying the transcription termination factor rho.
Mol Gen Genet 1976 Jan 16
PMID:Isolation and genetic characterization of the nitA mutants of Escherichia coli affecting the termination factor rho. 76 55


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