The ribonuclease H activity of the reverse transcriptases of human immunodeficiency viruses type 1 and type 2 is modulated by residue 294 of the small subunit
| Autor: | Shoshana Loya, Ziv Sevilya, Amnon Hizi, Noam Adir |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
DNA polymerase
RNase P Glutamine Recombinant Fusion Proteins Protein subunit Molecular Sequence Data Ribonuclease H DNA-Directed DNA Polymerase RNase PH Genetics Amino Acid Sequence RNase H Sequence Homology Amino Acid biology RNA-Directed DNA Polymerase Articles Molecular biology HIV Reverse Transcriptase Reverse transcriptase Kinetics Protein Subunits RNase MRP Amino Acid Substitution HIV-2 Mutation HIV-1 biology.protein |
| Zdroj: | Nucleic Acids Research. 31:1481-1487 |
| ISSN: | 1362-4962 |
| DOI: | 10.1093/nar/gkg235 |
| Popis: | Reverse transcriptases (RTs) exhibit DNA polymerase and ribonuclease H (RNase H) activities. The RTs of human immunodeficiency viruses type 1 and type 2 (HIV-1 and HIV-2) are composed of two subunits, both sharing the same N-terminus (which encompasses the DNA polymerase domain). The smaller subunit lacks the C-terminal segment of the larger one, which contains the RNase H domain. The DNA polymerase domain of RTs resembles a right hand linked to the RNase H domain by a connection subdomain. Despite the high homology between HIV-1 and HIV-2 RTs, the RNase H activity of the latter is substantially lower than that of HIV-1 RT. The thumb subdomain of the small subunit controls the level of RNase H activity. We show here that Gln294, located in this thumb, is responsible for this difference in activity. A HIV-2 RT mutant, where Gln294 in the small subunit was replaced by a proline (present in HIV-1 RT), has an activity almost 10-fold higher than that of the wild-type RT. A comparative in vitro study of the kinetic parameters of the RNase H activity suggests that residue 294 affects the K m rather than the k c a t value, influencing the affinity for the RNA.DNA substrate. |
| Databáze: | OpenAIRE |
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