Secondary structure of double-stranded DNA under stretching: elucidation of the stretched form

Almost two decades ago, measurements of force versus extension on isolated double-stranded DNA molecules revealed a force plateau. This unusual stretching phenomenon in DNA suggests that the long molecules may be extended from the usual B form into a new conformation. Different models have been prop...

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Bibliographic Details
Published in:Physical review. E, Statistical, nonlinear, and soft matter physics Statistical, nonlinear, and soft matter physics, 2011-03, Vol.83 (3 Pt 1), p.031903-031903, Article 031903
Main Authors: Maaloum, M, Beker, A-F, Muller, P
Format: Article
Language:English
Subjects:
ATOMIC AND MOLECULAR PHYSICS
ATOMIC FORCE MICROSCOPY
Bacteriophage lambda - genetics
BACTERIOPHAGES
Biophysics - methods
DIMENSIONS
DNA
DNA - chemistry
Image Processing, Computer-Assisted
LENGTH
Ligands
MATERIALS SCIENCE
MICROORGANISMS
MICROSCOPY
Microscopy, Atomic Force - methods
Molecular Conformation
MOLECULES
Nucleic Acid Conformation
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PARASITES
Software
VIRUSES
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Summary:Almost two decades ago, measurements of force versus extension on isolated double-stranded DNA molecules revealed a force plateau. This unusual stretching phenomenon in DNA suggests that the long molecules may be extended from the usual B form into a new conformation. Different models have been proposed to describe the nature of DNA in its stretched form, S-DNA. Using atomic force microscopy combined with a molecular combing method, we identified the structure of λ-phage DNA for different stretching values. We provide strong evidence for the existence of a first-order transition between B form and S form. Beyond a certain extension of the natural length, DNA molecules adopt a new double-helix conformation characterized by a diameter of 1.2 nm and a helical pitch of 18 nm.
ISSN:1539-3755
1550-2376
DOI:10.1103/PhysRevE.83.031903