Bo Wu
Xin Sui
Zhufeng Zhang
Tao Liu
Yingjun Li
Guoquan Hu
Mingxiong He
Nan Peng
aState Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
bKey Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Chengdu, Sichuan 610041, China
More InformationCorresponding author: E-mail address: hemingxiong@caas.cn (Mingxiong He);E-mail address: nanp@mail.hzau.edu.cn (Nan Peng)
Received Date: 2020-11-01
Accepted Date:2021-02-21
Rev Recd Date:2021-02-07
Available Online: 2021-03-29 Publish Date:2021-02-20
Abstract
Abstract
CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against mobile genetic elements (MGEs) through uptake of invader-derived spacers. De novo adaptation samples spacers from both invaders and hosts, whereas primed adaptation shows higher specificity to sample spacers from invaders in many model systems as well as in the subtype I-F system of Zymomonas mobilis. Self-derived spacers will lead to CRISPR self-interference. However, our in?vivo study demonstrated that this species used the microhomology-mediated end joining (MMEJ) pathway to efficiently repair subtype I-F CRISPR-Cas system-mediated DNA breaks guided by the self-targeting spacers. MMEJ repair of DNA breaks requires direct microhomologous sequences flanking the protospacers and leads to DNA deletions covering the protospacers. Importantly, CRISPR-mediated genomic DNA breaks failed to be repaired via MMEJ pathway in presence of higher copies of short homologous DNA. Moreover, CRISPR-cleaved exogenous plasmid DNA was failed to be repaired through MMEJ pathway, probably due to the inhibition of MMEJ by the presence of higher copies of the plasmid DNA inZ.?mobilis. Our results infer that MMEJ pathway discriminates DNA damages between in the host chromosome versus mobile genetic element (MGE) DNA, and maintains genome stability post CRISPR immunity in Z.?mobilis.Keywords: CRISPR-Cas,
CRISPR adaptation,
Self-interference,
Microhomology-mediated end joining
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