Structural and functional characterization of the C-terminal catalytic domain of SSV1 integrase.
The spindle-shaped virus SSV1 of the hyperthermophilic archaeon Sulfolobus shibatae encodes an integrase (SSV1 Int). Here, the crystal structure of the C-terminal catalytic domain of SSV1 Int is reported. This is the first structural study of an archaeal tyrosine recombinase. Structural comparison shows that the C-terminal domain of SSV1 Int possesses a core fold similar to those of tyrosine recombinases of both bacterial and eukaryal origin, apart from the lack of a conserved helix corresponding to αI of Cre, indicating conservation of these enzymes among all three domains of life. Five of the six catalytic residues cluster around a basic cleft on the surface of the structure and the nucleophile Tyr314 is located on a flexible loop that stretches away from the central cleft, supporting the possibility that SSV1 Int cleaves the target DNA in a trans mode. Biochemical analysis suggests that the N-terminal domain is responsible for the dimerization of SSV1 Int. The C-terminal domain is capable of DNA cleavage and ligation, but at efficiencies significantly lower than those of the full-length protein. In addition, neither the N-terminal domain alone nor the C-terminal domain alone shows a strong sequence preference in DNA binding. Therefore, recognition of the core-type sequence and efficient catalysis by SSV1 Int presumably requires covalent linkage and interdomain communication between the two domains.
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing 100101, People's Republic of China.
Zhengyan
Z
Zhan
Songying
S
Ouyang
Wenguang
W
Liang
Zhenfeng
Z
Zhang
Zhi Jie
ZJ
Liu
Li
L
Huang
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D019426:Integrases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D016944:Sulfolobus / Q000201:enzymology*
D019426:Integrases; C456321:SSV1 integrase