Reverse transcriptases can clamp together nucleic acids strands with two complementary bases at their 3′-termini for initiating DNA synthesis

Iris Oz-Gleenberg, Alon Herschhorn, Amnon Hizi

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

We present evidence that the reverse transcriptase (RT) of human immunodeficiency virus type-1 stabilizes in vitro very short (2-nt) duplexes of 3′-overhangs of the primer strand that are annealed to complementary dinucleotides tails of DNA or RNA template strands, provided that these sequences contain at least one C or G. This RT-induced strand 'clamping' activity promotes RT-directed DNA synthesis. This function is achieved only when the functional template strand is adjacent to a second DNA or RNA segment, annealed upstream to most of the primer (without gaps). The combined clamp/polymerase activity is typical to RTs, as it was found in different RTs from diverse retroviral groups, whereas cellular DNA-polymerases (devoid of 3′→5′ exonucleolytic activity) showed no clamp activity. The clamp-associated DNA-binding activity is markedly stabilized by dGTP, even when dGTP is not incorporated into the nascent DNA strand. The hereby-described function can help RTs in bridging over nicks in the copied RNA or DNA templates, encountered during reverse transcription. Moreover, the template-independent blunt-end synthesis of RTs can allow strand transfers onto compatible acceptor strands while synthesizing DNA. These RT properties can shed light on potentially-new roles of RTs in the reverse-transcription process and define new targets for anti-retroviral drugs.

Original languageEnglish (US)
Pages (from-to)1042-1053
Number of pages12
JournalNucleic acids research
Volume39
Issue number3
DOIs
StatePublished - Feb 2011

Bibliographical note

Funding Information:
The Israeli Science Foundation (grant No. 411/07).

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