Download MendeleyThe crystal structures of Sau3AI with and without bound DNA suggest a self-activation-based DNA cleavage mechanism.
Liu, Y., Xu, C., Zhou, H., Wang, W., Liu, B., Li, Y., Hu, X., Yu, F., He, J.(2023) Structure 31: 1463-1472.e2
- PubMed: 37652002 Search on PubMed
- DOI: https://doi.org/10.1016/j.str.2023.08.005
- Primary Citation Related Structures:
7XM0 - PubMed Abstract:
The type II restriction endonuclease Sau3AI cleaves the sequence 5'-GATC-3' in double-strand DNA producing two sticky ends. Sau3AI cuts both DNA strands regardless of methylation status. Here, we report the crystal structures of the active site mutant Sau3AI-E64A and the C-terminal domain Sau3AI-C with a bound GATC substrate. Interestingly, the catalytic site of the N-terminal domain (Sau3AI-N) is spatially blocked by the C-terminal domain, suggesting a potential self-inhibition of the enzyme. Interruption of Sau3AI-C binding to substrate DNA disrupts Sau3AI function, suggesting a functional linkage between the N- and C-terminal domains. We propose that Sau3AI-C behaves as an allosteric effector binding one GATC substrate, which triggers a conformational change to open the N-terminal catalytic site, resulting in the subsequent GATC recognition by Sau3AI-N and cleavage of the second GATC site. Our data indicate that Sau3AI and UbaLAI might represent a new subclass of type IIE restriction enzymes.
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan, Hubei 430030, China.
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