The SF1 helicase encoded by the archaeal plasmid pTN2 of Thermococcus nautili

We expressed, purified, and characterized the helicase encoded by ORF1 of the Thermococcus nautili pTN2 plasmid (Soler et al. Nucl Acids Res 38, 5088–5104, 2010 ). The enzyme, which belongs to the SF1 family of helicases, possesses NTPase activity, with a strong preference for ATP and GTP as compare...

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Bibliographic Details
Published in:Extremophiles : life under extreme conditions 2014-07, Vol.18 (4), p.779-787
Main Authors: Béguin, Pierre, Baron, Bruno, Gill, Sukhvinder, Charpin, Nicole, Forterre, Patrick
Format: Article
Language:English
Subjects:
Adenosine triphosphatase
Archaeal Proteins - genetics
Archaeal Proteins - metabolism
Biochemistry
Biomedical and Life Sciences
Biotechnology
Deoxyribonucleic acid
DNA
DNA Helicases - genetics
DNA Helicases - metabolism
DNA polymerase
DNA Replication
Life Sciences
Microbial Ecology
Microbiology
Original Paper
Plasmids
Protein synthesis
Space life sciences
Thermococcus
Thermococcus - enzymology
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Summary:We expressed, purified, and characterized the helicase encoded by ORF1 of the Thermococcus nautili pTN2 plasmid (Soler et al. Nucl Acids Res 38, 5088–5104, 2010 ). The enzyme, which belongs to the SF1 family of helicases, possesses NTPase activity, with a strong preference for ATP and GTP as compared to CTP and TTP; dATP was also a substrate. Triphosphatase activity was strongly stimulated by single-stranded DNA and, to a lesser extent, by double-stranded DNA. Unwinding of duplexes comprising a fluorescent oligonucleotide was monitored by fluorescence polarization spectroscopy and by polyacrylamide gel electrophoresis. As observed for enzymes of the same family, pTN2 helicase displays a strong preference for duplexes comprising a 3′ single-stranded extension and proceeds from the 3′ to the 5′ end of the loading strand. Under the conditions of the in vitro assay, pTN2 helicase did not appear to be recycled, but stayed bound to single-stranded DNA, which explains why high concentrations of enzyme are required to unwind long stretches of duplex DNA. The helicase enhances the synthesis of double-stranded DNA by pTN2 primase and by T. nautili PolB polymerase primed by pTN2 primase but it did not enhance synthesis by Taq DNA polymerase.
ISSN:1431-0651
1433-4909
DOI:10.1007/s00792-014-0658-5