Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An unusual protein splicing reaction joins the N-terminal segment (A) and the C-terminal segment (C) of the 119K primary translation product (ABC) of the yeast VMA1 gene to yield a 69K vacuolar H(+)-ATPase subunit (AC) and an internal 50K polypeptide (B). This 50K protein is a site-specific DNA endonuclease that shares 34% identity with the homothallic switching endonuclease. The site cleaved by the VMA1-derived endonuclease exists in a VMA1 allele that lacks the derived endonuclease segment of the open reading frame. Cleavage at this site only occurs during meiosis and initiates 'homing', a genetic event that converts a VMA1 allele lacking the endonuclease coding sequence into one that contains it.
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PMID:Homing of a DNA endonuclease gene by meiotic gene conversion in Saccharomyces cerevisiae. 153 48

We have previously demonstrated preferential DNA repair of active genes in mammalian cells. The methodology involves the use of a specific endonuclease or other more direct approaches to create nicks at sites of damage followed by quantitative Southern analysis and probing for specific genes. Initially, we used pyrimidine dimer specific endonuclease to detect pyrimidine dimers after UV irradiation. We now also use the bacterial enzyme ABC excinuclease to examine the DNA damage and repair of a number of adducts other than pyrimidine dimers in specific genes. We can detect gene specific alkylation damage by creating nicks via depurination and alkaline hydrolysis. In our assay for preferential repair, we compare the efficiency of repair in the DHFR gene to that in the 3' flanking, non-coding region to the gene. In CHO cells, UV induced pyrimidine dimers are efficiently repaired from the active DHFR gene, but not from the inactive region. We have demonstrated that the 6-4 photoproducts are also preferentially repaired and that they are removed faster from the regions studied than pyrimidine dimers. Using similar approaches, we find that DNA adducts and crosslinks caused by cisplatinum are preferentially repaired in the active gene compared to the inactive regions and to the inactive c-fos oncogene. Also, nitrogen mustard and methylnitrosurea damage is preferentially repaired whereas dimethylsulphate damage is not. NAAAF adducts do not appear to be preferentially repaired in this system.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Gene specific damage and repair after treatment of cells with UV and chemotherapeutical agents. 206 87

Recent studies by others have shown that the endonuclease complex coded for by the uvrA, uvrB and uvrC genes of Escherichia coli (UVR ABC excision nuclease) can incise DNA containing a variety of 'bulk-type' lesions, such as those resulting from u.v. light, (+/-)-7 alpha,8 beta-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE), and N-acetoxy-2-acetylaminofluorene. Using partially purified UVR ABC excision nuclease, we have quantitated the number of endonuclease sensitive sites (ESS) in purified DNA isolated from human fibroblasts treated with u.v. light or BPDE. The number of ESS/10(8) daltons of DNA were calculated from the number average mol. wt. of the DNA as determined by sedimentation in alkaline sucrose gradients. The number of endonuclease sites increased linearly with increasing doses of either u.v. light or BPDE. The UVR ABC excision nuclease was able to incise a majority of the BPDE-DNA adducts. Xeroderma pigmentosum fibroblasts, complementation group A (XP12BE) had 20-25% more ESS at each dose than the BPDE-treated normal (HSBP) cells. Cells treated with 4 microM BPDE and allowed 12 h of incubation to perform excision repair showed removal of 60% of the initial number of ESS from HSBP DNA and 40% of the ESS from XP-A DNA. Beyond 12 h XP12BE cells lost no additional ESS while HSBP cells continued to lose ESS, although at a slower rate, until at 48 h only 22% of the initial ESS remained. In cells treated with 10 J/m2 of u.v. light, the UVR ABC excision nuclease detected 60% of the sites recognized by the pyridimine dimer specific Micrococcus luteus glycosylase/apyrimidinic endonuclease. These results demonstrate the potential use of the UVR ABC excision nuclease in a quantitative assay for determining the number of carcinogen-induced lesions in human DNA.
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PMID:Quantitation of carcinogen-induced DNA damage and repair in human cells with the UVR ABC excision nuclease from Escherichia coli. 308 Feb 55

Excision repair in calcium-treated cells E. coli K12, which are usually used for transformation, was studied. A great decrease in excision repair capacity of calcium-treated cells compared to that of untreated cells was observed when cells were incubated in buffer. Analysis of excision repair in E. coli cells were performed by following methods: (1) plasmid DNA, treated in vivo with 8-methoxypsoralen (8-MOP) plus light (lambda less than 310 nm) was transformed into calcium-treated E. coli cells and excision of 8-MOP monoadducts was measured by method of repeated irradiation; (2) plasmid DNA, treated with 8-MOP plus light or irradiated at 254 nm in calcium-treated cells, was isolated, and conversion of supercoil plasmid DNA to relaxing form was detected by agarose gel electrophoresis. Excision repair capacity of calcium-treated cells was restored to the level of that of intact cells after the addition of carbon nutrients (L-broth, glucose). It is supposed that decrease in excision repair capacity of calcium-treated cells is due to the limitation of the intracellular energy sources (probably, ATP), required for the formation of single-stranded nicks in damaged DNA by UVR ABC--endonuclease.
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PMID:[Excision repair of plasmid in competent Escherichia coli cells]. 675 Mar 58

A survey of a vast range of mycobacterial strains led us to discover a new Pps1 intein allele in Mycobacterium gastri which differs from those of Mycobacterium tuberculosis and Mycobacterium leprae in both its sequence and insertion site. While little is known about Pps1, except that it belongs to the YC24 family of ABC transporters, we show that, unlike the other inteins described so far from Eubacteria, the MgaPps1 intein possesses a specific endonuclease activity. The intein is the first eubacterial intein to be characterised as an endonuclease. Like other intein endonucleases, its minimal sequence for recognition and cleavage is quite large, with 22 bp spanning the Pps1-c site. The fact that an active endonuclease is found among the mycobacterial inteins supports the concept of a cyclical model of invasion by horizontal transfer of these genes, followed by degeneration and loss until a new invasion event, thus explaining their long-term persistence in closely related eubacterial species.
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PMID:Identification of the first eubacterial endonuclease coded by an intein allele in the pps1 gene of mycobacteria. 1169 18

UvrA protein is a major component of ABC endonuclease complex involved in nucleotide excision repair (NER) mechanism. Although NER system is best characterized in Escherichia coli, not much information is available in Haemophilus influenzae. However, based on amino acid homology, uvrA ORF has been identified on H. influenzae genome [gene identification No. HI0249, Science 269 (1995) 496]. H. influenzae Rd uvrA ORF was cloned and overexpressed in E. coli. The expressed UvrA protein was purified using a two-step column chromatography protocol to a single band of expected molecular weight (104 kDa) and characterized for its ATPase and DNA binding activity. In addition, when H. influenzae uvrA was introduced in E. coli uvrA mutant strain AB1886, its UV resistance was restored to near wild type level.
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PMID:Haemophilus influenzae UvrA: overexpression, purification, and in cell complementation. 1535 71

Phosphate transport in bacteria occurs via a phosphate specific transporter system (PSTS) that belongs to the ABC family of transporters, a multisubunit system, containing an alkaline phosphatase. DING proteins were characterized due to the N-terminal amino acid sequence DINGG GATL, which is highly conserved in animal and plant isolates, but more variable in microbes. Most prokaryotic homologues of the DING proteins often have some structural homology to phosphatases or periplasmic phosphate-binding proteins. In E. coli, the product of the inducible gene DinG, possesses ATP hydrolyzing helicase enzymic activity. An alkaline phosphorolytic enzyme of the PSTS system was purified to homogeneity from the thermophilic bacterium Thermus thermophilus. N-terminal sequence analysis of this protein revealed the same high degree of similarity to DING proteins especially to the human synovial stimulatory protein P205, the steroidogenesis-inducing protein and to the phosphate ABC transporter, periplasmic phosphate-binding protein, putative (P. fluorescens Pf-5). The enzyme had a molecular mass of 40 kDa on SDS/PAGE, exhibiting optimal phosphatase activity at pH 12.3 and 70 degrees C. The enzyme possessed characteristics of a DING protein, such as ATPase, ds endonuclease and 3' phosphodiesterase (3'-exonuclease) activities and binding to linear dsDNA, displaying helicase activity on supercoiled DNA. Purification and biochemical characterization of a T. thermophilus DING protein was achieved. The biochemical properties, N-terminal sequence similarities of this protein implied that the enzyme belongs to the PSTS family and might be involved in the DNA repair mechanism of this microorganism.
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PMID:A DING phosphatase in Thermus thermophilus. 1749 5