Two Perspectives on the Twist of DNA

Biology – Quantitative Biology – Biomolecules

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

25 pages, 6 figures

Scientific paper

Because of the double-helical structure of DNA, in which two strands of complementary nucleotides intertwine around each other, a covalently closed DNA molecule with no interruptions in either strand can be viewed as two interlocked single-stranded rings. Two closed space curves have long been known by mathematicians to exhibit a property called the linking number, a topologically invariant integer, expressible as the sum of two other quantities, the twist of one of the curves about the other, and the writhing number, or writhe, a measure of the chiral distortion from planarity of one of the two closed curves. We here derive expressions for the twist of supercoiled DNA and the writhe of a closed molecule consistent with the modern view of DNA as a sequence of base-pair steps. Structural biologists commonly characterize the spatial disposition of each step in terms of six rigid-body parameters, one of which, coincidentally, is also called the twist. Of interest is the difference in the mathematical properties between this step-parameter twist and the twist of supercoiling associated with a given base-pair step. For example, it turns out that the latter twist, unlike the former, is sensitive to certain translational shearing distortions of the molecule that are chiral in nature. Thus, by comparing the values for the two twists for each step of a high-resolution structure of a protein-DNA complex, the nucleosome considered here, for example, we may be able to determine how the binding of various proteins contributes to chiral structural changes of the DNA.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

Two Perspectives on the Twist of DNA does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Two Perspectives on the Twist of DNA, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two Perspectives on the Twist of DNA will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-186470

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.