Force-induced melting of DNA-evidence for peeling and internal melting from force spectra on short synthetic duplex sequences

Bosaeus, Niklas,1982Chalmers tekniska högskola,Chalmers University of Technology (author)

Overstretching of DNA occurs at about 60-70 pN when a torsionally unconstrained double-stranded DNA molecule is stretched by its ends. During the transition, the contour length increases by up to 70% without complete strand dissociation. Three mechanisms are thought to be involved: force-induced melting into single-stranded DNA where either one or both strands carry the tension, or a B-to-S transition into a longer, still base-paired conformation. We stretch sequence-designed oligonucleotides in an effort to isolate the three processes, focusing on force-induced melting. By introducing site-specific inter-strand cross-links in one or both ends of a 64 bp AT-rich duplex we could repeatedly follow the two melting processes at 5 mM and 1 M monovalent salt. We find that when one end is sealed the AT-rich sequence undergoes peeling exhibiting hysteresis at low and high salt. When both ends are sealed the AT sequence instead undergoes internal melting. Thirdly, the peeling melting is studied in a composite oligonucleotide where the same AT-rich sequence is concatenated to a GC-rich sequence known to undergo a B-to-S transition rather than melting. The construct then first melts in the AT-rich part followed at higher forces by a B-to-S transition in the GC-part, indicating that DNA overstretching modes are additive.

El-Sagheer, AfafUniversity of Southampton (author)
Brown, T.University of Southampton (author)
Åkerman, Björn,1957Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)baa (author)
Nordén, Bengt,1945Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)norden (author)
Chalmers tekniska högskolaUniversity of Southampton (creator_code:org_t)

In:Nucleic Acids Research: Oxford University Press (OUP)42:12, s. 8083-80910305-10481362-4962

By the author/editor: Bosaeus, Niklas, ...; El-Sagheer, Afaf; Brown, T.; Åkerman, Björn, ...; Nordén, Bengt, 1 ...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Chemical Science ...; and Physical Chemist ...

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.