Sandbox Z-DNA: Difference between revisions

Z-DNA is relatively a new structural form of a DNA which has a different structure from the more common <scene name='Sandbox_Z-DNA/Bdna/1'>B-DNA</scene> form.It is a left-handed double helix wherein the sugar-phosphate backbone has a zigzag pattern due to the alternate stacking of bases in anti-conformation and syn conformation. In Z-DNA only a minor groove is present and the major groove is absent. The residues that allow sequence-specific recognition of Z-DNA are present on the convex outer surface.<ref name = 'Rich'> PMID:12838348</ref> Z-DNA is thought play a role in regulation of gene expression, DNA processing events and/or genetic instability.<ref name = 'Wang'>PMID:17485386</ref>

Z-DNA can form ''invitro'' from B-DNA by raising negative super helical stress or under physiological salt conditions when deoxycytosine is 5-methylated. The formation of Z-DNA which requires energy is an active process ''invivo''. A mechanism for initiation of Z-DNA involves formation of negative supercoils behind a moving  RNA polymerase when it moves through DNA double helix. <ref name = 'Rich'>PMID:12838348</ref> <ref name ='Wang'>PMID:17485386</ref> `