Atomic Model of a Pyrimidine Dimer Excision Repair Enzyme Complexed with a DNA Substrate:  Structural Basis for Damaged DNA Recognition

Cyclobutane thymine dimer (blue) and the flipped-out adenine base (red)
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Highlights the 60 degree kink formed by the DNA (space-filled) as it sits in the catalytic site of the enzyme(wireframe)

On average, the helical twist is 35.4 degrees.  Two base pairs, G-C & G-C, on the 3'-side of the flipped out adenine, exhibit a helical twist of 26.9 degrees.

Formation of a large "hole" (10A x 9A x 7A) between bases above and below the flipped out adenine

Near the carboxy terminus, a conformational change appears to be connected to the movements of the Arg-125 and Trp-128 side chains(red), which are induced by binding to DNA.  This loop partly overlaps the WYKYY (128-132) segment, which participates in DNA binding

Residues 83-91(red)--These residues are disordered when the enzyme is free of a substrate, but become well-defined when bound to DNA (green)

Polar Interactions between T4 Endo V (3'-side of PD in red and 5'-side in blue) and DNA backbone

Van der Waals contacts around flipped-out adenine base

UtilitiesColor Schemes

Next: T4 endonuclease V (Part II)

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