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

Experiments were performed to examine the role of cyclobutyl pyrimidine dimers in the process of mutagenesis by ultraviolet (u.v.) light. Lambda phage DNA was irradiated with u.v. and then incubated with an Escherichia coli photoreactivating enzyme, which monomerizes cyclobutyl pyrimidine dimers upon exposure to visible light. The photoreactivated DNA was packaged into lambda phage particles, which were used to infect E. coli uvr- host cells that had been induced for SOS functions by ultraviolet irradiation. Photoreactivation removed most toxic lesions from irradiated phage, but did not change the frequency of induction of mutations to the clear-plaque phenotype. This implies that cyclobutyl pyrimidine dimers can be lethal, but usually do not serve as sites of mutations in the phage. The DNA sequences of mutants derived from photoreactivated DNA showed that almost two-thirds (16/28) were transitions, the same fraction found for u.v. mutagenesis without photoreactivation. These results show that in this system, the lesion inducing transitions (the major type of u.v.-induced mutation) is not the cyclobutyl pyrimidine dimer; a strong candidate for a mutagenic lesion is the Pyr(6-4)Pyo photoproduct. On the other hand, photoreactivation of SOS-induced host cells before infection with u.v.-irradiated phage reduced mutagenesis substantially. In this case, photoreversal of cyclobutyl dimers serves to reduce expression of the SOS functions that are required in the process of targeted u.v. mutagenesis.
J Mol Biol 1985 Aug 20
PMID:Pyrimidine dimers are not the principal pre-mutagenic lesions induced in lambda phage DNA by ultraviolet light. 293 33

There is disagreement in the literature as to whether the major mutagenic photoproduct induced in DNA by ultraviolet light is the cyclobutane dipyrimidine dimer, the most common product, or the [6-4] photoproduct, the next most frequent. In the experiments reported here, cyclobutane dimers were removed from irradiated lambda phage DNA by enzymatic photoreactivation, a process thought to affect no other photoproduct. Photoreactivation of lambda phage in host cells and of lambda DNA in solution reduced clear plaque mutants per plaque-forming unit by two-thirds, in host cells with a constant and near-maximal expression of the SOS functions required for mutagenesis. This result is interpreted to mean that removal of cyclobutane dimers in or near the mutated gene reduces mutation induced by ultraviolet light by two-thirds; therefore, cyclobutane dimers in the phage DNA are responsible for most observed mutations. DNA sequences of mutations in photoreactivated phage showed a smaller fraction of G.C to A.T transitions and a larger fraction of A.T to G.C transitions, compared to phage that were not photoreactivated. This suggests that cyclobutane dimers at TC and CC sites are particularly mutagenic.
J Mol Biol 1988 Aug 05
PMID:Effect of photoreactivation on mutagenesis of lambda phage by ultraviolet light. 297 13

An Eimeria tenella cDNA library was constructed in the expression vector lambda gt11 from poly (A+) RNA extracted from sporulating oocysts. The library was screened with rabbit antiserum raised against antigens extracted from fully sporulated oocysts. All of the antigen-expressing plaque-purified clones were initially characterized by cross screening with antisera raised against different stages of the E. tenella life cycle, as well as with antiserum raised against sporozoites of a related species, namely E. acervulina. A selected number of clones were further characterized by antibody selection coupled with immunoblotting and DNA cross hybridization. Three different E. tenella antigens were identified. All three appear to be constitutively expressed at the protein level during sporogony.
Mol Biochem Parasitol 1988 Sep
PMID:Identification and characterization of cDNA clones encoding antigens of Eimeria tenella. 297 28

Helper T (Th) cells have shown to be heterogeneous both in their function and in their specificity. Several studies have demonstrated that there exist Th cells which do not appear to be specific for antigen:Ia complexes (not H-2 restricted) but interact with the target B cell via recognition of immunoglobulin idiotypic determinants. In analyzing anti-phosphorylcholine (PC) responses, such idiotype-specific Th cells are characterized by 1) their ability to increase responses to phosphorylcholine by augmenting selectively the activation of T15-idiotype-bearing PC-specific B cells, 2) their ability to bind specifically to T15-bearing immunoglobulin and 3) the dependence of their maturation on circulating T15 idiotype rather than Ia. Our aim is to explore further the relationship between Ia-specific and T15-specific Th cells. These studies describe the first step in comparing specificity and function of idiotype-specific Th cells to other known Th cells by the cloning of a T15-specific Lyl T cell (ThId) with properties consistent with those described for uncloned populations. The cloned ThId cells generated do not activate B cells to secrete antibody but augment anti-PC plaque forming cell (PFC) responses induced by Ia-restricted Th cells. This augmentation is seen only in the T15-bearing PFC responses even though non-T15-bearing B cells are equally accessible, and it is seen only in PC responses and not responses to TNP under identical culture conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Cell Immunol 1986
PMID:A cloned T cell line that selectively augments antibody responses of phosphorylcholine-specific B cells bearing the T15 idiotype. 297 29

Linear forms of simian virus 40 (SV40) DNA, when added to transfection mixtures containing circular SV40 and phi X174 RFI DNAs, enhanced the frequency of SV40/phi X174 recombination, as measured by infectious center in situ plaque hybridization in monkey BSC-1 cells. The sequences required for the enhancement of recombination by linear DNA reside within the SV40 replication origin/regulatory region (nucleotides 5,171 to 5,243/0 to 128). Linearization of phi X174 RFI DNA did not increase the recombination frequency. The SV40/phi X174 recombinant structures arising from transfections supplemented with linear forms of origin-containing SV40 DNA contained phi X174 DNA sequences interspersed within tandem head-to-tail repeats derived from the recombination-enhancing linear DNA. Evidence is presented that the tandem repeats are not formed by homologous recombination and that linear forms of SV40 DNA must compete with circular SV40 DNA for the available T antigen to enhance recombination. We propose that the enhancement of recombination by linear SV40 DNA results from the entry of that DNA into a rolling circle type of replication pathway which generates highly recombinogenic intermediates.
Mol Cell Biol 1985 Apr
PMID:Circular and linear simian virus 40 DNAs differ in recombination. 298 72

Three clones carrying the sequences of ceruloplasmin gene were isolated from the library of EcoRI fragments of rat chromosomal DNA cloned in Charon 4A vector. These clones were identified using, i) plaque hybridization with [32P] cDNA transcribed from highly purified rat ceruloplasmin (Cp) mRNA; ii) blot hybridization of the restriction fragments of recombinant DNAs with Cp cDNA and iii) hybridization selection of Cp mRNA followed by its cell-free translation. Oligo (dT)-primed cDNA transcripts of Cp mRNA having different length as well as cloned Cp cDNA isolated from rat liver cDNA library were used as hybridization probes for the study of mRNA-coding segments of Cp gene. The length of inserts in recombinant DNAs varied from 7.5 up to 12.3 megadaltons. EcoRI-fragments of Cp gene were mapped within recombinant DNA and their homology to each other was studied.
Mol Biol (Mosk)
PMID:[Comparative analysis of recombinant bacteriophages containing the sequences of the chromosomal ceruloplasmin gene in the rat]. 298 69

The mutation am6 in the cI gene of bacteriophage lambda is identified as a C----T transition in a 5'CCATGG sequence. In four-factor crosses of am6 with nearby mutations in cI, the frequencies of cI+ recombinants are much higher than expected from the physical distances. A very short patch (VSP) mismatch repair system is presumed to recognize am6/am+ mispairs in the heteroduplexes that accompany recombination between the outside markers. Mutation am6 is corrected to am+; correction of am+ to am6 was not detected. Clear-plaque mutation 1-1 in cI is a T----C transition in a 5'CTTGG sequence, resulting in the sequence 5'CCATGG. When 1-1 was crossed with nearby mutations in gene cI, there were no excess cI+ recombinants, which would result from repair of CCTGG (1-1) to CTTGG (cI+). However, in crosses of cI+ phages with mutation 1-1, there was an excess of cI- recombinants, indicating that cI+ was repaired to 1-1. Preferential repair does not require adenine or cytosine methylation: when repairing a mismatch, the VSP repair system apparently identifies specific mispaired bases by sequence alone.
Mol Gen Genet 1985
PMID:Recombination in the lambda repressor gene: evidence that very short patch (VSP) mismatch correction restores a specific sequence. 299 96

The in vitro mutagenesis of cloned DNAs allows the formation of virtually any specific mutation, but no method has been found which might routinely lead to the important phenotype of temperature sensitivity. We have studied three linker insertion mutations in the envelope gene of Moloney murine leukemia virus (M-MuLV), and found that one was exquisitely temperature-sensitive for plaque formation. We suggest that the construction of short insertion mutations may be a fruitful approach for the generation of temperature-sensitive phenotypes in cloned genes.
Mol Gen Genet 1985
PMID:A temperature-sensitive mutation constructed by "linker insertion" mutagenesis. 299 3

Two different PstI fragments of temperate phage phi 105 DNA are shown to confer superinfection immunity upon Bacillus subtilis when inserted into the multicopy cloning vector pE194 cop-6. The 2.3 kb PstI fragment I is located almost entirely within EcoRI fragment F and encompasses a region previously known to encode a repressor. The other fragment, PstI-E (4.3 kb) maps inside the EcoRI-B fragment, and allows an explanation of the clear-plaque phenotype of the deletion mutant phi 105DII:6c. The two regions can be distinguished functionally, since only the PstI fragment I product interacts with a specific phi 105 promoter-operator site.
Mol Gen Genet 1985
PMID:The temperate B. subtilis phage phi 105 genome contains at least two distinct regions encoding superinfection immunity. 299 68

Antigenic variants of pseudorabies virus (PRV) containing mutations in a viral glycoprotein with a molecular weight of 82,000 (gIII) were isolated by selecting for resistance to a complement-dependent neutralizing monoclonal antibody (MCA82-2) directed against gIII. These mutants were completely resistant to neutralization with MCA82-2 in the presence of complement. Two mutants selected for further studies either did not express gIII or expressed an improperly processed form of the glycoprotein. The mutations were also associated with an altered plaque morphology (syncytium formation). The gIII gene was mapped by marker rescue of a gIII- mutant with cloned restriction enzyme fragments to the long unique region of the PRV genome between 0.376 and 0.383 map units. This corresponds to the map location of a glycoprotein described by Robbins et al. (J. Mol. Appl. Gen. 2:485-496, 1984). Since gIII is nonessential for viral replication in cell culture and has several other characteristics in common with the herpes simplex virus glycoprotein gC, gIII may represent the PRV equivalent to herpes simplex virus gC.
 ...
PMID:Characterization and mapping of a nonessential pseudorabies virus glycoprotein. 300 46


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>