Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations were introduced into the P2 and P1 positions of the junctions, (a) linking reverse transcriptase (RT) and integrase (IN) (-Leu*Phe-) and (b) between the p51 and RNase H domain (-Phe*Tyr-) within p66 of RT in the HIV-1 pol polyprotein. Processing by HIV proteinase (PR) in cis was monitored upon expression of these constructs in E. coli. Whereas the presence of Leu or Phe in P1 permitted rapid cleavage at either junction, substitution of a beta-branched (Ile) hydrophobic residue essentially abolished hydrolysis. By contrast, placement of a beta-branched (Val) residue in the P2 position flanking such -Hydrophobic*Hydrophobic- junctions resulted in effective cleavage of the scissile peptide bond. Gly in P2, however, abrogated cleavage. The significance of these findings in terms of PR specificity, polyprotein processing and the generation of homodimeric (p51/p51) RT for crystallisation purposes is discussed.
 ...
PMID:Mutating P2 and P1 residues at cleavage junctions in the HIV-1 pol polyprotein. Effects on hydrolysis by HIV-1 proteinase. 204 56

Approximately 80 percent of all human sera that react with antigens of HTLV-III, the etiologic agent of the acquired immune deficiency syndrome (AIDS), recognize protein bands at 66 and 51 kilodaltons. A mouse hybridoma was produced that was specific to these proteins. Repeated cloning of the hybridoma did not separate the two reactivities. The p66/p51 was purified from HTLV-III lysates by immunoaffinity chromatography and subjected to NH2-terminal Edman degradation. Single amino acid residues were obtained in 17 successive degradation cycles. The sequence determined was a perfect translation of the nucleotide sequence of a portion of the HTLV-III pol gene. The purified p66/51 had reverse transcriptase activity and the monoclonal immunoglobulin G specifically removed the enzyme activity from crude viral extract as well as purified enzyme.
 ...
PMID:Characterization of highly immunogenic p66/p51 as the reverse transcriptase of HTLV-III/LAV. 241 4

The ability to express the genes of pathogenic human viruses, such as the acquired immune deficiency syndrome (AIDS) virus (also called human immunodeficiency virus) in bacterial cells affords the opportunity to study proteins that are ordinarily difficult or inconvenient to obtain in amounts sufficient for detailed analysis. A segment of the AIDS virus pol gene was expressed in Escherichia coli. Expression resulted in the appearance of reverse transcriptase activity in the bacterial cell extracts. The extracts contained two virus-related polypeptides that have the same apparent molecular weights as the two processed forms of virion-derived reverse transcriptase (p66 and p51). The formation of these two polypeptides depended on the coexpression of sequences located near the 5' end of the pol gene, a region that is thought to encode a viral protease. This bacterial system appears to generate mature forms of the AIDS virus reverse transcriptase by a proteolytic pathway equivalent to that which occurs during virus infection of human cells.
 ...
PMID:Expression and processing of the AIDS virus reverse transcriptase in Escherichia coli. 243 98

We have constructed a plasmid that, when introduced into Escherichia coli, induces the synthesis of large quantities of a protein with an apparent molecular mass of 66 kDa that differs from human immunodeficiency virus (HIV) RNA-dependent DNA polymerase (deoxynucleoside-triphosphate:DNA deoxynucleotidyltransferase or reverse transcriptase, EC 2.7.7.49) only in that it has two additional amino-terminal amino acids. This protein is soluble in E. coli extracts, is active in reverse transcriptase assays, and shows inhibition profiles with dideoxy-TTP and dideoxy-GTP that are indistinguishable from the viral enzyme. The deletion of 23 amino-terminal or carboxyl-terminal amino acids or the insertion of 5 amino acids at position 143 substantially decreases the polymerizing activity of the HIV reverse transcriptase made in E. coli. The properties of a 51-kDa reverse transcriptase-related protein made in E. coli suggests that the p51 found in the virion probably does not have substantial polymerizing activity. The full-length HIV reverse transcriptase and the various mutant proteins produced in E. coli should be quite useful for structural and biochemical analyses as well as for the production of antibodies.
 ...
PMID:Expression of soluble, enzymatically active, human immunodeficiency virus reverse transcriptase in Escherichia coli and analysis of mutants. 244 94

An activity gel analysis was performed in order to examine the catalytically active component of human immunodeficiency virus (HIV) reverse transcriptase in purified enzyme preparations and HIV-infected cell extracts. Immunoaffinity purified HIV reverse transcriptase contains two proteins with molecular weights 66,000 and 51,000 in approximately equal proportions. After denaturing polyacrylamide gel electrophoresis and removal of sodium dodecyl sulfate, the p66 component of reverse transcriptase was sufficient for both DNA- and RNA-directed DNA synthesis. No DNA synthetic activity of p51 was observed. Recovery of p66 catalytic activity was approximately 10% that of DNA polymerase beta, and the density of the autoradiographic band corresponding to p66 was linear with enzyme concentration. No additional HIV-specific DNA polymerases besides p66 were observed in HIV-infected H9 cell extracts.
 ...
PMID:Enzyme activity gel analysis of human immunodeficiency virus reverse transcriptase. 245 63

Human immune deficiency virus (HIV) replicates by conversion of the RNA genome into the double-stranded DNA provirus. The reverse transcriptase is not the only enzymatic function crucial in DNA-provirus synthesis. A viral-coded RNase H activity which specifically degrades RNA in RNA-DNA hybrids has been shown to be essential as well. Here we demonstrate that the HIV-reverse transcriptase which consists of a two-polypeptide complex, p66 and p51, copurifies with an RNase H activity which exhibits properties of a processive exonuclease. Only the p66 molecule, not p51, is active as polymerase as evidenced by activated gel analysis. p66 exhibits RNase H activity when precipitated as immune complex by a monoclonal antibody raised against a bacterially expressed carboxy-terminal portion of p66. The monoclonal antibody which does not interfere with enzyme activity also precipitates a second population of molecules with RNase H activity which is of low mol. wt, p15. This RNase H appears therefore to be derived from the carboxy terminus of p66 during processing to the p51 polypeptide. It exhibits low template-binding ability and is of a non-processing mode of action which may be due to the absence of the reverse transcriptase domain. These results lend experimental support to the hypothesis that the RNase H gene maps at the carboxy terminus of the reverse transcriptase. Since both RNase H populations are virus-coded they may be essential for retrovirus replication in general and useful targets for chemotherapeutic agents.
 ...
PMID:Identification and characterization of HIV-specific RNase H by monoclonal antibody. 245 83

The HIV immunoblot profiles of 700 HIV-antibody-positive sera were examined to determine the frequency of antibody reactivity with p66/p51, the reverse transcriptase of HIV. We report a remarkably high seroprevalence of antibodies to p66/p51, detected in 79% of the sera. Only gp41 is recognized more frequently in these assays. The level of anti-p66/p51 seroreactivity varies only slightly among the clinical stages of HIV infection.
 ...
PMID:High prevalence of serum antibodies to reverse transcriptase in HIV-1-infected individuals. 245 48

The reverse transcriptase of HIV-1 (AIDS virus) is characterized by the presence of two highly immunogenic proteins of 66 and 51 kD known to be enzymatically active as a complex p66/51. Using an activity gel procedure that allows identification of catalytic polypeptides in situ after PAGE in denaturing conditions, we visualized two major active bands of 66 and 51 kD of reverse transcriptase from highly purified preparations of HIV-1. We show that both p66 and p51 are enzymatically active. An additional active band was also associated with a 165 kD polypeptide, representing about 2-4% of total activity and possibly corresponding to the putative gag-pol precursor. In H9-infected cells the 66 kD active band became visible 70 hours after infection. These studies show that the two major forms of reverse transcriptase (66 and 51 kD) of HIV-1 are independently active and that a higher Mr form of 165 kD is also enzymatically active.
 ...
PMID:Enzymatically active forms of reverse transcriptase of the human immunodeficiency virus. 246 25

A plasmid construct expressing the p66 version of the human immunodeficiency virus reverse transcriptase as a bacterial fusion protein was subjected to in vitro mutagenesis, and the resulting variant proteins were assayed to define the locations of the two major enzymatic activities. The DNA polymerase activity was localized to the N-terminal portion of the protein; mutations altering or eliminating the C-terminal portion had little or no effect on that activity. The results suggest that, in contrast with previous reports, the p51 subunit found in virions should exhibit DNA polymerase activity. Mutations in many parts of the protein eliminated RNase H activity, suggesting that several areas are needed for proper folding and generation of that activity.
 ...
PMID:Linker insertion mutagenesis of the human immunodeficiency virus reverse transcriptase expressed in bacteria: definition of the minimal polymerase domain. 247 90

To investigate a non-RI test which is equivalent to the reverse transcriptase inhibiting antibody test, a reverse transcriptase inhibiting antibody was compared to the absolute number of CD-4 or CD-8 cells or CD-4/-8 ratio and also to photodensitometric analysis for western blotting. There is no correlation of the reverse transcriptase with any test for cell numbers and their ratio. In photodensitometry, relative units of anti-p65 and anti-p51 were compared with reverse transcriptase inhibiting antibody. The reverse transcriptase inhibiting antibody showed a higher correlation to the relative unit of p65 antibodies than that of p51 antibodies. The photodensitometric analysis of western blotting for a serum test may be a possible method to find a prognostic marker in HIV-1 infection.
 ...
PMID:[Comparative evaluation of markers with reverse transcriptase inhibiting antibody in human immunodeficiency virus type 1 infection]. 247 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>