Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Molecular evolution and phylogeny of different human immunodeficiency virus type 1 (HIV1) strains, of a type 2 (HIV2) strain, and of two simian immunodeficiency viruses (SIVAGM and SIVMAC) have been studied by comparing the nucleotide sequences of the two regions of their pol genes which encode the reverse transcriptase (RT) and endonuclease/integrase (EN). The analyses show that the different HIV 1s form one cluster (HIV1 group) and that the SIVs and HIV2 form another (HIV2 group). When the entire genomes of a HIV1, a HIV2, and the two SIVs were compared, the SIVAGM showed a unique pattern of mutation accumulations; that is, the SIVAGM has accumulated more nonsynonymous changes than synonymous changes in the RT and EN regions after its recent divergence from SIVMAC-142, and, furthermore, it has a deletion of approximately 350 bp in the region between the pol and env genes. The SIVAGM was apparently derived from cell cultures infected with a macaque isolate, SIVMAC-251. The contamination provides an opportunity to measure the maximum rate of evolution in the SIVAGM by comparing its DNA sequence to those of SIVMAC-251 and SIVMAC-142. The analysis shows that the rates are given approximately by (1.95 +/- 1.37) x 10(-3)/site/year for one SIVAGM sequence and (5.18 +/- 2.25) x 10(-3)/site/year for another.
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PMID:Molecular evolution of the human and simian immunodeficiency viruses. 246 34

Feline leukemia virus (FeLV) C-Sarma (or FSC) is a prototype of subgroup C FeLVs, which induce fatal aplastic anemia in outbred specific-pathogen-free (SPF) cats. FeLV C isolates also possess an extended host range in vitro, including an ability, unique among FeLVs, to replicate in guinea pig cells. To identify the viral determinants responsible for the pathogenicity and host range of FSC we constructed a series of proviral DNAs by exchanging gene fragments between FSC and FeLV-61E (or F6A), the latter of which is minimally pathogenic and whose host range in vitro is restricted to feline cells. Transfer of an 886-base-pair (bp) fragment of FSC, encompassing the codons for 73 amino acids at the 3' end of pol (the integrase/endonuclease gene) and the codons for 241 amino acids of the N-terminal portion of env [the extracellular glycoprotein (gp70) gene], into the F6A genome was sufficient to confer onto chimeric viruses the ability to induce fatal aplastic anemia in SPF cats. In contrast, no chimera lacking this sequence induced disease. When assayed in vitro, all chimeric viruses containing the 886-bp fragment of FSC acquired the ability to replicate in heterologous cells, including dog and guinea pig cells. Thus, the pathogenic and the host range determinants of the feline aplastic anemia retrovirus colocalize to a 3' pol-5' env region of the FSC genome and likely reside within a region encoding 241 amino acid residues of the N terminus of the extracellular glycoprotein.
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PMID:Pathogenic and host range determinants of the feline aplastic anemia retrovirus. 283 51

The present studies were initiated to define the coding region of a 34 kilodalton (kd) protein (p34) frequently observed with antibodies from HTLV-III/LAV-infected people by immunoblotting and radioimmunoprecipitation (RIP) techniques. We have directly mapped this viral protein to the pol gene of HTLV-III/LAV by radiolabeled amino acid sequence analysis. This region at the 3' end of the pol gene is predicted to encode the endonuclease/integrase of the virus. The seroprevalence rate of antibodies to the pol gene products p64 and p53 and to the endonuclease p34 were evaluated. Of 161 HTLV-III/LAV seropositive people tested by immunoblotting procedures, greater than 98% had antibodies which reacted to p64/p53 and 92.6% reacted to p34 indicating that these viral proteins are highly immunogenic in nature. We have also analyzed the serum of nine healthy people living in West Africa who were infected with HTLV-IV, a closely related retrovirus. Nine of nine seropositive people had antibodies that cross-reacted to p34 of HTLV-III/LAV, whereas only seven of nine reacted to p64/p53. These studies and our earlier observations indicate that current diagnostic procedures for screening for HTLV-III/LAV infection may also detect HTLV-IV seropositive individuals, pointing to a need for more specific assay systems.
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PMID:Immunogenic nature of a Pol gene product of HTLV-III/LAV. 302 60

A phylogenetic tree for different human immunodeficiency viruses type 1 (HIV1) and type 2 (HIV2), lentiviruses, and oncoviruses has been constructed by comparing the nucleotide sequences of the two regions of their pol genes that encode the reverse transcriptase and endonuclease/integrase. The analysis indicates that (1) different HIV1 strains form one cluster and their common ancestor diverged from the ancestor of HIV2, (2) the common ancestor of the HIV1 and HIV2 strains diverged from that of the lentivirus, and (3) the common ancestor of the lentivirus group and that of the oncoviruses diverged earlier than that. Divergence between the HIV1 and HIV2 strains seems to have occurred greater than 200 years ago, implying that AIDS has existed for a long time but went undetected. Furthermore, nonsynonymous changes are occurring uniformly through time, whereas synonymous changes are more variable among different lineages.
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PMID:Molecular evolution of the human immunodeficiency and related viruses. 338 28

A 93-kb region (D region) of plasmid pAE1 of Alcaligenes eutrophus H1 has been found to have a high rate of spontaneous deletion. In this study, we constructed a restriction endonuclease map and carried out limited sequencing of an approximately 100-kb region from pAE1 which includes the D region (the deleted region) in order to detect and characterize repetitive sequences. Two types of repetitive sequences, the R1 and R2 sequences, were observed to flank the D region; within the D region are three copies of insertion element ISAE1. The R1 and R2 sequences are arranged in direct and inverted orientations, respectively. Molecular analysis of the end product of the deletion is consistent with the hypothesis that the loss of the D-region DNA is the result of recombination between two copies of the R1 sequence. The R1 sequence encodes a 415-amino-acid protein which exhibits substantial sequence similarity to the lambda integrase family of site-specific recombinases. Its genetic function remains to be determined.
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PMID:Molecular characterization of a deletion-prone region of plasmid pAE1 of Alcaligenes eutrophus H1. 760 94

The bacterial expression plasmids, pET3b and pET16b, that contain the integrase domain of the human foamy virus (HFV) reverse transcriptase were constructed and expressed in Escherichia coli. The histidine-tagged HFV IN protein was purified to near homogeneity by single-step Ni2+ chelate affinity chromatography. HFV-specific proteins of 39 and 120 kDa from virus-infected cells reacted with antisera raised against the recombinant IN protein. Purified recombinant HFV IN protein was active as an endonuclease specifically cleaving two nucleotides from a 20-bp oligodeoxynucleotide substrate that mimics the authentic 5' ends of HFV DNA. Substrates with mutations relatively close to the cleavage site were less efficiently cleaved or not cleaved at all compared with the HFV U5 DNA end. The purified recombinant protein was active as integrase with double-stranded oligodeoxynucleotide substrates. The reverse reaction of DNA strand transfer, the disintegration activity, was shown by efficient cleavage of an intermediate Y-shaped oligodeoxynucleotide. In the presence of Mn2+ as the preferred divalent cation, oligodeoxynucleotides were specifically and efficiently cleaved. In contrast, endonucleolytic cleavages in the presence of Mg2+ ions led to a broad range of reaction products with the His-tagged HFV IN protein. After further purification of the HFV IN by cation-exchange chromatography, the unspecific degradation of oligonucleotide substrate in the presence of Mg2+ was not detectable.
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PMID:Endonucleolytic cleavages and DNA-joining activities of the integration protein of human foamy virus. 768 24

The recently reported crystal structures of two recombination enzymes, the catalytic domain of HIV integrase and Escherichia coli RuvC, an endonuclease, are surprisingly similar to that of ribonuclease H suggesting the possibility that they have a common enzymatic mechanism.
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PMID:Recombining the structures of HIV integrase, RuvC and RNase H. 773 28

The human spuma retrovirus or foamy virus integrase (HFV IN) is an enzymatically active protein consisting of domains similar to other retroviral integrases: an amino-terminal HH-CC finger, a centrally located region with the conserved D, D-35-E protein motif required for catalytic activity and oligomerization, and at least one DNA binding domain implicated in the 3' DNA processing activity and integrase. Recombinant, purified HFV IN protein carrying 10 histidine residues displays a site-specific endonuclease, an integrase, and a disintegrase activity with oligonucleotide substrates that mimic the viral long terminal repeat (LTR) ends. Site-directed mutagenesis of conserved HFV IN residues of the catalytic domain had increased endonuclease and disintegrase activities. Deletion mutants at both ends of the HFV IN protein were generated, purified, and characterized. Unexpectedly, it was found that the HFV integrase and disintegrase activities require an intact NH2-terminal sequence and that COOH-terminal deletions led to an increase in disintegrase activity. The HH-CC finger of HFV IN was exchanged with that of the human immunodeficiency virus-1 (HIV-1) IN protein. The resulting chimeric IN had a 3' processing activity that utilized the HFV LTR instead of the HIV LTR, indicating that the central domain is crucial for substrate recognition. Functional complementation of the amino-terminal deletion mutant of HFV IN was achieved by a carboxyl-terminal deletion mutant of the chimeric IN, resulting in high levels of integrase activity.
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PMID:Characterization of the human spuma retrovirus integrase by site-directed mutagenesis, by complementation analysis, and by swapping the zinc finger domain of HIV-1. 785 75

The prevalence of trimethoprim resistance in enterobacterial urinary pathogens from hospitalised patients in the Angus district of northern Scotland (22.8%) was twice that found in similar isolates from patients attending general practitioners (11.2%). Thirty-three of the 143 trimethoprim-resistant strains were shown to harbour transferable plasmids conferring high-level trimethoprim resistance. In total, 17 different plasmid types were distinguished. Two plasmids, pUK1184 and pUK1185, accounted for 36% of the trimethoprim resistance plasmids and were shown by restriction endonuclease digestion fingerprints to be closely related to plasmid pUK28, previously demonstrated to be endemic in urinary pathogens in the Edinburgh area. Only 21% of the plasmids were shown to encode the type Ia trimethoprim-resistant dihydrofolate reductase, whereas 70% of the trimethoprim resistance plasmids were found to encode the type Ib dihydrofolate reductase. Hybridisation of the trimethoprim resistance plasmids identified in this study with gene probes specific for the integrase genes of transposons Tn7 and Tn21 indicates that the dhfrIa is rarely present within Tn7 or related transposons in these plasmids and may be more prevalent within Tn21-like transposons. In contrast, with the exception of the two endemic plasmids that harboured the dhfrIb gene within a Tn7-like transposon, the majority of dhfrIb genes were not found to be associated with either Tn7- or Tn21-like structures.
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PMID:Trimethoprim resistance in urinary pathogens in northern Scotland: epidemic spread of a resistance plasmid encoding the type Ib trimethoprim-resistant dihydrofolate reductase. 796 7

Although integration generally is considered a critical step in the retrovirus life cycle, it has been reported that visna virus, which causes degenerative neurologic disease in sheep, can productively infect sheep choroid plexus cells without detectable integration. To ascertain whether the integrase (IN) of visna virus is an inherently defective enzyme and to create tools for further study of integration of the phylogenetically related human immunodeficiency virus type 1 (HIV-1), we purified visna virus IN by using a bacterial expression system and applied various in vitro oligonucleotide-based assays to studying this protein. We found that visna virus IN demonstrates the full repertoire of in vitro functions characteristic of retroviral integrases. In particular, visna virus IN exhibits site-specific endonuclease activity following the invariant CA found two nucleotides from the 3' ends of viral DNA (processing activity), joins processed oligonucleotides to various sites on other oligonucleotides (strand transfer or integration activity), and reverses the integration reaction by resolving a complex that mimics one end of viral DNA integrated into host DNA (disintegration activity). In addition, although it has been reported that purified HIV-1 IN cannot specifically nick visna virus DNA ends, purified visna virus IN does specifically process and integrate HIV-1 DNA ends.
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PMID:In vitro activities of purified visna virus integrase. 818 95


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