Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-terminal amino acid sequencing, ion spray mass spectrometry, and cleavage of synthetic peptide substrates were used to identify the N and C termini of the mature Gag and Pol proteins of feline immunodeficiency virus (FIV). The Gag polyprotein encodes matrix (MA), capsid (CA), and nucleocapsid (NC) proteins. The Gag-Pol polyprotein encodes, in addition to the above proteins, protease (PR), reverse transcriptase (RT), dUTPase (DU), and integrase (IN). Secondary cleavage of RT at Trp-595-Tyr-596 of Pol yields a truncated form lacking the C-terminal RNase H domain. The observed and expected molecular masses of the viral proteins were in agreement, with three exceptions. (i) The molecular mass of MA was 14,735 Da, compared with a predicted mass of 14,649 Da, based on a single cleavage at Tyr-135-Pro-136 of Gag. The observed molecular mass is consistent with myristoylation of MA, which was confirmed by metabolic labeling of FIV MA with [3H]myristic acid. (ii) The N terminus of the NC protein is generated via cleavage at Gln-366-Val-367 of Gag, which predicts a mass of 25,523 for CA and 9,101 for the major form of NC. The observed mass of CA was 24,569, consistent with loss of nine C-terminal amino acids by a second cleavage of CA at Leu-357-Leu-358. Synthetic FIV protease accurately cleaved synthetic peptide substrates containing this site. (iii) The actual mass of NC (7,120 Da) was approximately 2 kDa smaller than the mass predicted by synthesis to the stop codon at the end of Gag (9,101 Da). Experiments are in progress to characterize additional cleavage(s) in NC.
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PMID:Identification of proteolytic processing sites within the Gag and Pol polyproteins of feline immunodeficiency virus. 838 14

The putative dUTPase domain was deleted from the polymerase (pol) gene of equine infectious anemia virus (EIAV) to produce a recombinant delta DUpol Escherichia coli expression cassette and a delta DU proviral clone. Expression of the recombinant delta DUpol polyprotein yielded a properly processed and enzymatically active reverse transcriptase, as determined by immunoblot analysis and DNA polymerase activity gels. Transfection of delta DU provirus into feline (FEA) cells resulted in production of virus that replicated to wild-type levels in both FEA cells and fetal equine kidney cells. In contrast, the delta DU virus replicated poorly (less than 1% of wild-type levels) in primary equine macrophage cultures, as measured by reverse transcriptase assays. Preparations of delta DU virus contained negligible dUTPase activity, which confirms that virion-associated dUTPase is encoded in the pol gene region between the RNase H domain and integrase, as has been demonstrated previously for feline immunodeficiency virus (J. H. Elder, D. L. Lerner, C. S. Hasselkus-Light, D. J. Fontenot, E. Hunter, P. A. Luciw, R. C. Montelaro, and T. R. Phillips, J. Virol. 66:1791-1794, 1992). Our results suggest that virus-encoded dUTPase is dispensable for virus replication in dividing cells in vitro but may be required for efficient replication of EIAV in nondividing equine macrophages, the natural host cells for this virus.
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PMID:Characterization of equine infectious anemia virus dUTPase: growth properties of a dUTPase-deficient mutant. 838 67

Many retroviruses either encode dUTP pyrophosphatase (dUTPase) or package host-derived uracil DNA glycosylase as a means to limit the accumulation of uracil in DNA strands, suggesting that uracil is detrimental to one or more steps in the viral life cycle. In the present study, the effects of DNA uracilation on (-) strand DNA synthesis, RNase H activity, and (+) strand DNA synthesis were investigated in a cell-free system. This system uses the activities of purified human immunodeficiency virus type 1 (HIV-1) reverse transcriptase to convert single-stranded RNA to double-stranded DNA in a single reaction mixture. Substitution of dUTP for dTTP had no effect on (-) strand synthesis but significantly decreased yields of (+) strand DNA. Mapping of nascent (+) strand 5' ends revealed that this was due to decreased initiation from polypurine tracts with a concomitant increase in initiation at non-polypurine tract sites. Aberrant initiation correlated with a change in RNase H cleavage specificity when assayed on preformed RNA-DNA duplexes containing uracilated DNA, suggesting that appropriate "selection" of the (+) strand primer is affected. Collectively, these data suggest that accumulation of uracil in retroviral DNA may disrupt the viral life cycle by altering the specificity of (+) strand DNA synthesis initiation during reverse transcription.
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PMID:Incorporation of uracil into minus strand DNA affects the specificity of plus strand synthesis initiation during lentiviral reverse transcription. 1245 16

The complete genome of the Piper yellow mottle virus (PYMoV), a Badnavirus belonging to the family Caulimoviridae, was sequenced from three naturally infected hosts namely, black pepper, betelvine, and Indian long pepper. The genome length of the three virus strains (one from each of the three host species) varied from 7,559 to 7,584 nucleotides, and all the three strains possessed four open reading frames (ORFs) I to IV that potentially encode proteins of 15.67, 17.08, 218.6, and 17.22 kDa, respectively. ORF III encodes a polyprotein consisting of viral movement protein, trimeric dUTPase, zinc finger, aspartic protease, reverse transcriptase, and RNase H whereas ORF I, II, and IV encode proteins of unknown functions. The complete genome sequences at the nucleotide level were 89-99 % identical with one available sequence of PYMoV and 39-56 % identical with other badnaviruses, indicating that all three are strains of PYMoV. Nucleotide and amino acid sequences of ORF I-IV and of the intergenic region (IR) were 80-100 % identical among PYMoV strains. Phylogenetic analysis of ORF III amino acid sequences showed the PYMoV strains forming a distinct cluster well separated from other badnaviruses. Among other badnaviruses, Fig badnavirus 1 (FBV-1) was the one most closely related to PYMoV.
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PMID:Complete genome sequencing of Piper yellow mottle virus infecting black pepper, betelvine, and Indian long pepper. 2533 43