File talk:Nucleosome structure.png

The dsDNA twist around the nucleosome

The twist of the DNA around the nucleosome core is the other way round as it actually is. I've just revised it in the last edition of Benjamin Lewin's Genes IX edition, and I now have no doubt. It can also be deduced from the fact that the nucleosomic DNA has 10.17 base pairs per twist whereas the relaxed B-DNA double helix has 10.5bp. The extra twists of the double helix in the nucleosomic DNA are counterbalanced by the negative supercoiling caused by twisting the DNA around the nucleosome cores. Since the B-DNA double helix is right-handed, the supercoiling allowing the extra twists has to necessarily be left-handed. I would improve myself the article to give the DNA the correct orientation around the nucleosome core, but I don't have the original templates. I've thought in mirroring an inverted picture but there are some words which would become hard to read Heathmoor (talk) 14:51, 24 June 2010 (UTC)