Photolyase groove

Fig. 4. Structure of Escherichia coli photolyase. (A) Ribbon diagram representation. The MTHF antenna is exposed on the surface, whereas the FADH catalytic cofactor is buried within the core of the a-helical domain. (B) Surface potential representation. Blue, basic residues red, acidic residues white, hydrophobic residues. Note the positively charged groove running diagonally the length of the protein and the hole (marked by a square) with asymmetric charge distribution along the side walls and leading to the flavin located in the bottom. (See Color Insert.)...

Fig. 9. Model for human cryptochrome 2. The model was computer generated using the Escherichia coli DNA photolyase as a template the C-terminal 80 amino acids of hCRY2 were excluded. Left, ribbon representation. Right, surface potential representation. Note the presence of the positively charged groove on the surface and passing through the hole leading to the FAD cofactor in the core of the a-helical domain. (See Color Insert.)...

Molecular modeling of mammalian cryptochromes on the structure of photolyase indicates conservation of the chromophore-binding regions, the DNA binding groove, as weU as the damage-binding pocket. However, the functional implications of these structural features for cryptochrome function in circadian photoreception are unknown. The major difference between cryptochrome and photolyase Hes in the presence of an extended C-terminal tail in cryptochrome, which is absent in photolyase. Based on... 

The crystal structures of all photolyases revealed a globular shape and the presence of two coenzymes at a distance of 16.8 A and 17.5 A to each other, respectively. Every photolyase known today contains one FAD-cofactor bound in a cavity with the right dimension and polarity to also accommodate the DNA lesion. The architecture suggests that photolyases recognize the lesion substrate in a flipped out conformation. The second coenzyme, either a methenyltetrahydrofolate (MTHF) (Type-I photolyases) or a 5-deazaflavin (5-DF) (Type-II photolyase), depending on the type of photolyase, is bound in a shallow groove close to the surface of the protein (Figure 141.3). 

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