Initiation and re-initiation of DNA unwinding by the Escherichia coli Rep helicase

Taekjip Ha (), Ivan Rasnik, Wei Cheng, Hazen P. Babcock, George H. Gauss, Timothy M. Lohman and Steven Chu
Additional contact information
Taekjip Ha: University of Illinois
Ivan Rasnik: University of Illinois
Wei Cheng: Washington University School of Medicine
Hazen P. Babcock: Stanford University
George H. Gauss: Washington University School of Medicine
Timothy M. Lohman: Washington University School of Medicine
Steven Chu: Stanford University

Nature, 2002, vol. 419, issue 6907, 638-641

Abstract: Abstract Helicases are motor proteins that couple conformational changes induced by ATP binding and hydrolysis with unwinding of duplex nucleic acid1,2,3, and are involved in several human diseases. Some function as hexameric rings4, but the functional form of non-hexameric helicases has been debated5,6,7,8,9,10. Here we use a combination of a surface immobilization scheme and single-molecule fluorescence assays—which do not interfere with biological activity—to probe DNA unwinding by the Escherichia coli Rep helicase. Our studies indicate that a Rep monomer uses ATP hydrolysis to move toward the junction between single-stranded and double-stranded DNA but then displays conformational fluctuations that do not lead to DNA unwinding. DNA unwinding initiates only if a functional helicase is formed via additional protein binding. Partial dissociation of the functional complex during unwinding results in interruptions (‘stalls’) that lead either to duplex rewinding upon complete dissociation of the complex, or to re-initiation of unwinding upon re-formation of the functional helicase. These results suggest that the low unwinding processivity observed in vitro for Rep is due to the relative instability of the functional complex. We expect that these techniques will be useful for dynamic studies of other helicases and protein–DNA interactions.

Date: 2002
References: Add references at CitEc
Citations: View citations in EconPapers (3)

Downloads: (external link)
https://www.nature.com/articles/nature01083 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:419:y:2002:i:6907:d:10.1038_nature01083

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/nature01083

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().