The phage-encoded excisionase protein (Xis, Swiss:P03699) is involved in excisive recombination by regulating the assembly of the excisive intasome and by inhibiting viral integration. It adopts an unusual 'winged'-helix structure in which two alpha ...
The phage-encoded excisionase protein (Xis, Swiss:P03699) is involved in excisive recombination by regulating the assembly of the excisive intasome and by inhibiting viral integration. It adopts an unusual 'winged'-helix structure in which two alpha helices are packed against two extended strands. Also present in the structure is a two-stranded anti-parallel beta-sheet, whose strands are connected by a four-residue 'wing'. During interaction with DNA, helix alpha2 is thought to insert into the major groove, while the wing contacts the adjacent minor groove or phosphodiester backbone. The C-terminal region of Xis is involved in interaction with phage-encoded integrase (Int), and a putative C-terminal alpha helix may fold upon interaction with Int and/or DNA [1].
Bacteriophage lambda integrase, Arm DNA-binding domain
The amino terminal domain of bacteriophage lambda integrase folds into a three-stranded, antiparallel beta-sheet that packs against a C-terminal alpha-helix, adopting a fold that is structurally related to the three-stranded beta-sheet family of DNA- ...
The amino terminal domain of bacteriophage lambda integrase folds into a three-stranded, antiparallel beta-sheet that packs against a C-terminal alpha-helix, adopting a fold that is structurally related to the three-stranded beta-sheet family of DNA-binding domains (which includes the GCC-box DNA-binding domain and the N-terminal domain of Tn916 integrase). This domain is responsible for high-affinity binding to each of the five DNA arm-type sites and is also a context-sensitive modulator of DNA cleavage [1].
