MCB9 - DNA Topology and Topoisomerases Lk ≡ integral...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: DNA Topology and Topoisomerases Lk ≡ integral number of times one strand wraps around another Wr ∝ Number of times the DNA duplex wraps around itself Lk = Tw + Wr Tw ∝ N/h (Number of bp divided by DNA pitch) (pitch ≈ 10.5bp/turn) Tw always positive for B-DNA (right handed), strongly constrained by pitch If Wr≈0, Lk≈Tw If Tw is constant, and Lk changes, Wr must change (and vice versa) ∆Lk = ∆Tw + ∆Wr Non-zero values of Wr → supercoiling Wr can be either positive or negative Right handed Left handed Increasing supercoiling Luger et al., Nature, 1997 ∆Lk=-1, topoisomerase Increasing [EtBr] Intercalator Todd et al. J Med. Chem 1999 Chemla et al., Nature 2001 Redinbo et al., Science 1998 II Y III ssDNA Binding DNA Cleavage IV I DNA Release Strand passage Religation Classen et al., PNAS 2003; Dong & Berger Nature 2007 Corbett et al., Nat Struct Mol Biol 2007 1 2 4 3 ADP ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online