DNA synthesis fidelity by the reverse transcriptase of the yeast retrotransposon Ty1

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FONTE

Oxford University Press

RESUMO

The fidelity of the yeast retrotransposon Ty1 reverse transcriptase (RT) was determined by an assay based on gel electrophoresis. Steady-state kinetics analyses of deoxyribonucleotide (dNTP) incorporation at a defined primer-template site indicate that Ty1 RT misincorporates dNTP at a frequency of 0.45 × 10–5 for the At:A mispair in which dATP is misincorporated opposite a template A to 6.27 × 10–5 for the Ct:A mispair. The Gt:G and Tt:T mispairs are formed with very low efficiency. The fidelity parameters of Ty1 RT do not depend on whether RNA or DNA are copied. Relative to lentiviral RTs (HIV-1, HIV-2 or EIAV) Ty1 RT is ∼10-fold less error prone. Our data also show that the Ty1 RT is able to recapitulate two error-generating mechanisms: extension of mismatches and non-templated addition of nucleotides at the end of a blunt-end primer-template.

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