Two symmetric arginine residues play distinct roles in Thermus thermophilus Argonaute DNA guide strand-mediated DNA target cleavage
Type
ArticleAuthors
Lei, JinpingSheng, Gang
Cheung, Peter Pak-Hang
Wang, Shenglong
Li, Yu
Gao, Xin

Zhang, Yingkai
Wang, Yanli
Huang, Xuhui

KAUST Department
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) DivisionComputer Science Program
Computational Bioscience Research Center (CBRC)
KAUST Grant Number
OSR-2016-CRG5-3007Date
2018-12-27Online Publication Date
2018-12-27Print Publication Date
2019-01-15Permanent link to this record
http://hdl.handle.net/10754/630879
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Bacterium Thermus thermophilus Argonaute (Ago; TtAgo) is a prokaryotic Ago (pAgo) that acts as the host defense against the uptake and propagation of foreign DNA by catalyzing the DNA cleavage reaction. The TtAgo active site consists of a plugged-in glutamate finger with two arginine residues (R545 and R486) located symmetrically around it. An interesting challenge is to understand how they can collaboratively facilitate enzymatic catalysis. In Kluyveromyces polysporus Ago, a eukaryotic Ago, the evolutionarily symmetrical residues are arginine and histidine, both of which function to stabilize the plugged-in catalytic tetrad conformation. Surprisingly, our simulation results indicated that, in TtAgo, only R545 is involved in the cleavage reaction by serving as a critical structural anchor to stabilize the catalytic tetrad Asp-Glu-Asp-Asp that is completed by the insertion of the glutamate finger, whereas R486 is not involved in target cleavage. The TtAgo-mediated target DNA cleavage occurs in a substrate-assisted mechanism, in which the pro-Rp (Rp, a tetrahedral phosphorus center with "R-type" chirality) oxygen of scissile phosphate acts as a general base to activate the nucleophilic water. Our unexpected theoretical findings on distinct roles played by R545 and R486 in TtAgo catalysis have been validated by single-point site-mutagenesis experiments, wherein the target cleavage is abolished for all mutants of R545. In sharp contrast, the cleavage activity is maintained for all mutants of R486. Our work provides mechanistic insights on the catalytic specificity of Ago proteins and could facilitate the design of new gene-editing tools in the long term.Citation
Lei J, Sheng G, Cheung PP-H, Wang S, Li Y, et al. (2018) Two symmetric arginine residues play distinct roles in Thermus thermophilus Argonaute DNA guide strand-mediated DNA target cleavage. Proceedings of the National Academy of Sciences 116: 845–853. Available: http://dx.doi.org/10.1073/pnas.1817041116.Sponsors
This work was supported by Hong Kong Research Grant Council (Hong Kong University of Science and Technology) Grants C6009-15G, 16318816, 16302214, AoE/P-705/16, and T31-605/18-W; King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) Grant OSR-2016-CRG5-3007; Innovation and Technology Commission Grants ITCPD/17-9 and ITC-CNERC14SC01; National Natural Science Foundation of China Grants 31725008, 31571335, and 31630015; and National Institutes of Health Grant R35-GM127040. This research made use of the resources of the Supercomputing Laboratory at KAUST. X.H. is the Padma Harilela Associate Professor of Science.Additional Links
https://www.pnas.org/content/116/3/845ae974a485f413a2113503eed53cd6c53
10.1073/pnas.1817041116