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)

We characterized the simian immunodeficiency virus isolated from Cercopithecus aethiops (subspecies C. a. pygerythrus) originating from Kenya. SIV was isolated and continuously produced with the MOLT4 clone 8 cell line and was designated as SIV-SU1. SIV-SU1 isolate replicated with high efficiency in MOLT4 clone 8, MT-2 with moderate efficiency in CEM x 174 and with poor efficiency in HUT-78, U937, C8166. The infection of MT-2, C8166 and HUT-78 resulted in extensive cell killing. Western blotting of purified preparations of SIV-SU1 revealed viral proteins of 130, 68, 55, 41, 24, 17 kDa. Cross-reactivity of SIV-SU1 proteins with HIV-1, HIV-2, SIVmac, SIVsm, SIVmnd was studied by radioimmunoprecipitation assay. The most extensive cross-reactivity was observed with SIVmac. Total cellular DNA from chronically infected cells was hybridized to SIVagm266 DNA probes. Detection of cross-hybridizing DNA sequences required very low stringency, and the restriction endonuclease fragmentation pattern of SIV-SU1 differed from other SIVs.
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PMID:[The isolation and characteristics of the green monkey lentivirus]. 805 27

Two commercially available expression vectors were modified to generate plasmids pGEXcPk and pQ9cPk. Proteins expressed from pGEXcPk and pQ9cPk had a short oligopeptide tag termed Pk at their carboxy termini and either glutathione S-transferase (GST) or a small histidine (His) tag, respectively, at their N termini. GST fusion proteins can be purified on immobilized glutathione and proteins coupled to the His tag selectively bind to Ni(2+)-NTA columns. The Pk tag is recognized by monoclonal antibody (MAb) SV5-P-k, previously produced in our laboratory. Thus proteins expressed from the pGEXcPk and pQ9cPk vectors can be purified in a two-step procedure, first via the N-terminal tag and second via the C-terminal tag. The combination of two affinity purification steps significantly improves the antigen purity and selects for full-size proteins. Moreover, by using the MAbSV5-P-k in the second purification step, Pk-linked antigens can be assembled directly into solid matrix-antibody-antigen (SMAA) complexes for use as vaccines. The genes for nef, endonuclease, p15, p17, p27, protease, Rev, reverse transcriptase (rt), tat, vif, vpr, and vpx of simian immunodeficiency virus (SIV mac 251) were cloned and expressed as both GST-SIV-Pk and His-SIV-Pk proteins. Multivalent SMAA complexes were made that contained His-p17-Pk, His-p27-Pk, His-rt-Pk, His-vpx-Pk, and His-vpr-Pk. Following two immunizations of mice with this mixture, antibodies could be detected to all five SIV antigens. When compared to single-protein immunizations, the immunogenicity of some of the proteins in this cocktail was either enhanced or decreased. Mice were also immunized with His-p17-Pk or His-p17-Pk-antibody complexes in the presence or absence of alum. The antibody-antigen complexes induced two- to four-fold higher antibody levels than antigen alone but did not appear to be more immunogenic in inducing lymphoproliferative responses. Sera from SIV-infected macaques were tested for the presence of antibodies reacting with the recombinant proteins by Western blot analysis. Antibodies to endonuclease, p15, p17, p27, rt, and vif were readily detected, antibodies against protease and vpx were present at much lower levels, but no antibodies were detected to nef, rev, tat, or vpr. Thus, we have developed a comprehensive range of reagents (available on request) that can be used to examine immune responses to SIV in both mice and monkeys.
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PMID:Expression and purification of nonglycosylated SIV proteins, and their use in induction and detection of SIV-specific immune responses. 807 30

Retroviruses and retrotransposons are vulnerable to a suicidal pathway known as autointegration, which occurs when the 3'-ends of the reverse transcript are activated by integrase and then attack sites within the viral DNA. Retroelements have diverse strategies for suppressing autointegration, but how HIV-1 protects itself from autointegration is not well-understood. Here we show that knocking down any of the components of the SET complex, an endoplasmic reticulum-associated complex that contains 3 DNases (the base excision repair endonuclease APE1, 5'-3' exonuclease TREX1, and endonuclease NM23-H1), inhibits HIV-1 and HIV-2/SIV, but not MLV or ASV, infection. Inhibition occurs at a step in the viral life cycle after reverse transcription but before chromosomal integration. Antibodies to SET complex proteins capture HIV-1 DNA in the cytoplasm, suggesting a direct interaction between the SET complex and the HIV preintegration complex. Cloning of HIV integration sites in cells with knocked down SET complex components revealed an increase in autointegration, which was verified using a novel semi-quantitative nested PCR assay to detect autointegrants. When SET complex proteins are knocked down, autointegration increases 2-3-fold and chromosomal integration correspondingly decreases approximately 3-fold. Therefore, the SET complex facilitates HIV-1 infection by preventing suicidal autointegration.
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PMID:The SET complex acts as a barrier to autointegration of HIV-1. 1926 25

Evolutionarily conserved structure-selective endonuclease MUS81 forms a complex with EME1 and further associates with another endonuclease SLX4-SLX1 to form a four-subunit complex of MUS81-EME1-SLX4-SLX1, coordinating distinctive biochemical activities of both endonucleases in DNA repair. Viral protein R (Vpr), a highly conserved accessory protein in primate lentiviruses, was previously reported to bind SLX4 to mediate down-regulation of MUS81. However, the detailed mechanism underlying MUS81 down-regulation is unclear. Here, we report that HIV-1 Vpr down-regulates both MUS81 and its cofactor EME1 by hijacking the host CRL4-DCAF1 E3 ubiquitin ligase. Multiple Vpr variants, from HIV-1 and SIV, down-regulate both MUS81 and EME1. Furthermore, a C-terminally truncated Vpr mutant and point mutants R80A and Q65R, all of which lack G2 arrest activity, are able to down-regulate MUS81-EME1, suggesting that Vpr-induced G2 arrest is not correlated with MUS81-EME1 down-regulation. We also show that neither the interaction of MUS81-EME1 with Vpr nor their down-regulation is dependent on SLX4-SLX1. Together, these data provide new insight on a conserved function of Vpr in a host endonuclease down-regulation.
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PMID:SLX4-SLX1 Protein-independent Down-regulation of MUS81-EME1 Protein by HIV-1 Viral Protein R (Vpr). 2735 82