Expression of an active form of recombinant Ty1 reverse transcriptase in Escherichia coli: a fusion protein containing the C-terminal region of the Ty1 integrase linked to the reverse transcriptase–RNase H domain exhibits polymerase and RNase H activities
| Autor: | Mansour Boutabout, F.X. Wilhelm, M.L. Wilhelm |
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| Rok vydání: | 2000 |
| Předmět: |
Retroelements
Recombinant Fusion Proteins Molecular Sequence Data Ribonuclease H Retrotransposon Saccharomyces cerevisiae Biology Biochemistry Chromatography Affinity law.invention Open Reading Frames law Escherichia coli Amino Acid Sequence Cloning Molecular RNase H Molecular Biology Polymerase Integrases Sequence Homology Amino Acid Nucleic Acid Heteroduplexes RNA-Directed DNA Polymerase DNA Templates Genetic Cell Biology Fusion protein Molecular biology HIV Reverse Transcriptase Reverse transcriptase Integrase Kinetics Terminator (genetics) Codon Terminator biology.protein Recombinant DNA RNA Sequence Alignment Research Article |
| Zdroj: | Biochemical Journal. 348:337-342 |
| ISSN: | 1470-8728 0264-6021 |
| DOI: | 10.1042/bj3480337 |
| Popis: | Replication of the Saccharomyces cerevisiae Ty1 retrotransposon requires a reverse transcriptase capable of synthesizing Ty1 DNA. The first description of an active form of a recombinant Ty1 enzyme with polymerase and RNase H activities is reported here. The Ty1 enzyme was expressed as a hexahistidine-tagged fusion protein in Escherichia coli to facilitate purification of the recombinant protein by metal-chelate chromatography. Catalytic activity of the recombinant protein was detected only when amino acid residues encoded by the integrase gene were added to the N-terminus of the reverse transcriptase-RNase H domain. This suggests that the integrase domain could play a role in proper folding of reverse transcriptase. Several biochemical properties of the Ty1 enzyme were analysed, including the effect of MgCl2, NaCl, temperature and of the chain terminator dideoxy GTP on its polymerase activity. RNase H activity was examined by monitoring the cleavage of a RNA-DNA template-primer. Our results suggest that the distance between the RNase H and polymerase active sites corresponds to the length of a 14-nucleotide RNA-DNA heteroduplex. The recombinant protein produced in E. coli should be useful for further biochemical and structural analyses and for a better understanding of the role of integrase in the activation of reverse transcriptase. |
| Databáze: | OpenAIRE |
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