Characterization of the DNA-unwinding activity of human RECQ1, a helicase specifically stimulated by human replication protein A

Sheng Cui, Raffaella Klima, Alex Ochem, Daniele Arosio, Arturo Falaschi, Alessandro Vindigni

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

The RecQ helicases are involved in several aspects of DNA metabolism. Five members of the RecQ family have been found in humans, but only two of them have been carefully characterized, BLM and WRN. In this work, we describe the enzymatic characterization of RECQ1. The helicase has 3′ to 5′ polarity, cannot start the unwinding from a blunt-ended terminus, and needs a 3′-single-stranded DNA tail longer than 10 nucleotides to open the substrate. However, it was also able to unwind a blunt-ended duplex DNA with a "bubble" of 25 nucleotides in the middle, as previously observed for WRN and BLM. We show that only short DNA duplexes (<30 bp) can be unwound by RECQ1 alone, but the addition of human replication protein A (hRPA) increases the processivity of the enzyme (>100 bp). Our studies done with Escherichia coli single-strand binding protein (SSB) indicate that the helicase activity of RECQ1 is specifically stimulated by hRPA. This finding suggests that RECQ1 and hRPA may interact also in vivo and function together in DNA metabolism. Comparison of the present results with previous studies on WRN and BLM provides novel insight into the role of the N- and C-terminal domains of these helicases in determining their substrate specificity and in their interaction with hRPA.

Original languageEnglish
Pages (from-to)1424-1432
Number of pages9
JournalJournal of Biological Chemistry
Volume278
Issue number3
DOIs
StatePublished - Jan 17 2003

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