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

We have recently characterized Nicotiana cytoplasmic (cyt) tRNA(GCA)Cys as a novel UGA suppressor tRNA. Here we have isolated its corresponding (NtC1) and a variant (NtC2) gene from a genomic library of Nicotiana rustica. Both tRNA(Cys) genes are efficiently transcribed in HeLa cell nuclear extract and yield mature cyt tRNAs(Cys). Sequence analysis of the upstream region of the RAD51 single-copy gene of the Arabidopsis thaliana genome revealed a cluster of three tRNA(Cys) genes which have the same polarity and comprise highly similar flanking sequences. Of the three Arabidopsis tRNA(Cys) genes only one (i.e. AtC2) appears to code for a functional gene which exhibits an almost identical nucleotide sequence to NtC1. These are the first sequenced nuclear tDNAs(Cys) of plant origin.
Plant Mol Biol 1996 Nov
PMID:Nucleotide sequences of nuclear tRNA(Cys) genes from Nicotiana and Arabidopsis and expression in HeLa cell extract. 898 May 5

A gene encoding a RecA/RAD51 homologue from a hyperthermophilic archaeon, Pyrococcus sp. KOD1 (Pk), was cloned, sequenced and expressed in Escherichia coli. The deduced 210-amino acid sequence was compared to homologues from bacteria (RecA), eukaryotes (RAD51, DMC1) and archaea (RadA). The entire protein from Pk (Pk-REC) basically corresponds to the essential central domain of its counterparts and lacks the two smaller RecA subdomains at the N- and C-termini. The sequence comparison suggests that Pk-REC represents a common prototype of RecA, RAD51, DMC1 and RadA, with higher enzymatic activity. Recombinant Pk-REC was fully active and complemented the ultraviolet light sensitivity of an E. coli recA mutant strain.
Mol Gen Genet 1996 Dec 13
PMID:A RecA/RAD51 homologue from a hyperthermophilic archaeon retains the major RecA domain only. 900 28

By deleting the radA open reading frame of an extreme halophile, Haloferax volcanii, we created and characterized a recombination-deficient archaeon. This strain, Hf. volcanii DS52, has no detectable DNA recombination, is more sensitive to DNA damage by UV light and ethylmethane sulfonate, and has a slower growth rate than the wild type. These characteristics are similar to those observed in recombination mutants of Eukarya and Bacteria, and show that the radA gene belongs in the recA/RAD51 family by function as well as sequence homology. In addition, strain DS52 was not transformable by plasmids pWL102 or pUBP2 (which contain pHV2 and pHH1 replicons, respectively), although it was readily transformed by plasmids containing a pHK2 replicon, indicating a role for radA in the maintenance or replication of some halobacterial plasmids. Despite its slower growth rate, Hf. volcanii DS52 was still easy to culture and transform, and should be suitable for use in studies where a recombination-deficient background is desired.
Mol Microbiol 1997 Feb
PMID:Construction and analysis of a recombination-deficient (radA) mutant of Haloferax volcanii. 915 49

We have cloned the uvsC gene of Aspergillus nidulans by complementation of the A. nidulans uvsC114 mutant. The predicted protein UVSC shows 67.4% sequence identity to the Saccharomyces cerevisiae Rad51 protein and 27.4% sequence identity to the Escherichia coli RecA protein. Transcription of uvsC is induced by methyl-methane sulphonate (MMS), as is transcription of RAD51 of yeast. Similar levels of uvsC transcription were observed after MMS induction in a uvsC+ strain and the uvsC114 mutant. The coding sequence of the uvsC114 allele has a deletion of 6 bp, which results in deletion of two amino acids and replacement of one amino acid in the translation product. In order to gain more insight into the biological function of the uvsC gene, a uvsC null mutant was constructed, in which the entire uvsC coding sequence was replaced by a selectable marker gene. Meiotic and mitotic phenotypes of a uvsC+ strain, the uvsC114 mutant and the uvsC null mutant were compared. The uvsC null mutant was more sensitive to both UV and MMS than the uvsC114 mutant. The uvsC114 mutant arrested in meiotic prophase-I. The uvsC null mutant arrested at an earlier stage, before the onset of meiosis. One possible interpretation of these meiotic phenotypes is that the A. nidulans homologue of Rad51 of yeast has a role both in the specialized processes preceding meiosis and in meiotic prophase I.
Mol Gen Genet 1997 May
PMID:Cloning, sequencing, disruption and phenotypic analysis of uvsC, an Aspergillus nidulans homologue of yeast RAD51. 920 81

The Saccharomyces cerevisiae RAD51 gene product takes part in genetic recombination and repair of DNA double strand breaks. Rad51, like Escherichia coli RecA, catalyzes strand exchange between homologous circular single-stranded DNA (ssDNA) and linear double-stranded DNA (dsDNA) in the presence of ATP and ssDNA-binding protein. The formation of joint molecules between circular ssDNA and linear dsDNA is initiated at either the 5' or the 3' overhanging end of the complementary strand; joint molecules are formed only if the length of the overhanging end is more than 1 nucleotide. Linear dsDNAs with recessed complementary or blunt ends are not utilized. The polarity of strand exchange depends upon which end is used to initiate the formation of joint molecules. Joint molecules formed via the 5' end are processed by branch migration in the 3'-to-5' direction with respect to ssDNA, and joint molecules formed with a 3' end are processed in the opposite direction.
Mol Cell Biol 1997 Sep
PMID:Characterization of strand exchange activity of yeast Rad51 protein. 927 13

Normal diploid cells have a limited replicative potential in culture, with progressively increasing interdivision time. Rarely, cell lines arise which can divide indefinitely; like tumor cells, such "immortal" lines display frequent chromosomal aberrations which may reflect high rates of recombination. Recombination frequencies within a plasmid substrate were 3.5-fold higher in nine immortal human cell lines than in six untransformed cell strains. Expression of HsRAD51, a human homolog of the yeast RAD51 and Escherichia coli recA recombinase genes, was 4.5-fold higher in immortal cell lines than in mortal cells. Stable transformation of human fibroblasts with simian virus 40 large T antigen prior to cell immortalization increased both chromosomal recombination and the level of HsRAD51 transcripts by two- to fivefold. T-antigen induction of recombination was efficiently blocked by introduction of HsRAD51 antisense (but not control) oligonucleotides spanning the initiation codon, implying that HsRAD51 expression mediates augmented recombination. Since p53 binds and inactivates HsRAD51, T-antigen-p53 association may block such inactivation and liberate HsRAD51. Upregulation of HsRAD51 transcripts in T-antigen-transformed and other immortal cells suggests that recombinase activation can also occur at the RNA level and may facilitate cell transformation to immortality.
Mol Cell Biol 1997 Dec
PMID:Elevated recombination in immortal human cells is mediated by HsRAD51 recombinase. 937 47

A newly isolated mutant, mus-23, of Neurospora crassa was found to be highly sensitive to a wide variety of mutagens, including UV light, methyl methanesulfonate, 4-nitroquinoline 1-oxide, N-methyl-N'-nitro-N-nitrosoguanidine and tert-butyl hydroperoxide. This mutant was originally isolated as a mutant that could not grow on medium containing histidine. Meiosis and sporulation were defective in homozygous crosses between mus-23 haploids. The mus-23 gene is located on the right arm of LGII, between fl and trp-3. Analyses of epistasis between mus-23 and other mutations that cause defects in DNA repair indicated that the mus-23 gene belongs to the same DNA repair group as mei-3, which is the Neurospora homolog of the Saccharomyces cerevisiae gene RAD51. The double mutant carrying mus-23 and uvs-3 mutations was lethal. The mus-23 gene was cloned by complementation of the MMS-sensitive phenotype of the mus-23 mutant. The gene contained an open reading frame of 1578 bp and did not contain any introns. The molecular weight of the predicted mus-23 gene product was 60.4 kDa. Computer analyses revealed that the MUS23 protein has significant homology to Mre11p, which is known to be involved in recombinational repair in S. cerevisiae. The level of mus-23 transcripts increased significantly within 60 min of treatment with UV or MMS and then gradually decreased. The role of MUS23 protein in recombinational repair is discussed.
Mol Gen Genet 1997 Oct
PMID:Genetic and molecular characterization of Neurospora crassa mus-23: a gene involved in recombinational repair. 939 41

By using RT-PCR and degenerate oligonucleotides based on the sequence homology between the yeast RAD51 and DMC1 genes, two genes belonging to the RAD51 and DMC1 families were isolated from Arabidopsis thaliana ecotype Columbia. A RAD51 genomic DNA was also sequenced which is almost identical to its Landsberg erecta counterpart, except for a few translationally silent substitutions and for the presence of a 527-bp element downstream of the polyadenylation site. This element is repeated in the genome of Arabidopsis. Northern analyses were conducted to characterize the expression pattern of both these genes. AtRAD51 and AtDMC1 are expressed in flower buds, but also in the mitotically active cells from a suspension culture. AtRAD51, but not AtDMC1, transcript level increases after gamma irradiation of the cells. Finally, a synchronisation experiment conducted with the suspension culture indicated that not only AtRAD51 but also AtDMC1 are regulated during the cell cycle, with S-phase-specific induction. Since DMC1 genes have always been regarded as being specifically meiotic, we discuss the significance of this mitotic transcriptional regulation in Arabidopsis.
Mol Gen Genet 1998 Feb
PMID:Isolation and characterisation of the RAD51 and DMC1 homologs from Arabidopsis thaliana. 952 Feb 62

The uvsC gene of Aspergillus nidulans is a homolog of the RAD51 gene of Saccharomyces cerevisiae. However, with respect to its effects on UV mutagenesis, it differs from the yeast gene, since it seems to be required for UV mutagenesis; however, this conclusion is based only on data from resting conidia. To further clarify the functional role of the uvsC gene, we tested the UV mutability of strains bearing a uvsC mutation in resting as well as in germinating conidia, by the p-fluorophenyl-alanine resistance test. We also evaluated the mutability of the uvsE mutant which belongs to the same epistatic group. Our results show that the uvsC and uvsE genes do not have a significant role in the mutagenic UV-repair pathway.
Mol Gen Genet 1998 Jul
PMID:The uvsC and uvsE genes of Aspergillus nidulans are not required for the mutagenic repair of UV damage. 973 89

Rad52 plays a pivotal role in double-strand break (DSB) repair and genetic recombination in Saccharomyces cerevisiae, where mutation of this gene leads to extreme X-ray sensitivity and defective recombination. Yeast Rad51 and Rad52 interact, as do their human homologues, which stimulates Rad51-mediated DNA strand exchange in vitro, suggesting that Rad51 and Rad52 act cooperatively. To define the role of Rad52 in vertebrates, we generated RAD52(-/-) mutants of the chicken B-cell line DT40. Surprisingly, RAD52(-/-) cells were not hypersensitive to DNA damages induced by gamma-irradiation, methyl methanesulfonate, or cis-platinum(II)diammine dichloride (cisplatin). Intrachromosomal recombination, measured by immunoglobulin gene conversion, and radiation-induced Rad51 nuclear focus formation, which is a putative intermediate step during recombinational repair, occurred as frequently in RAD52(-/-) cells as in wild-type cells. Targeted integration frequencies, however, were consistently reduced in RAD52(-/-) cells, showing a clear role for Rad52 in genetic recombination. These findings reveal striking differences between S. cerevisiae and vertebrates in the functions of RAD51 and RAD52.
Mol Cell Biol 1998 Nov
PMID:Homologous recombination, but not DNA repair, is reduced in vertebrate cells deficient in RAD52. 977 59


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