期刊
NATURE COMMUNICATIONS
卷 13, 期 1, 页码 -出版社
NATURE PORTFOLIO
DOI: 10.1038/s41467-022-30402-8
关键词
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资金
- Royal Society of New Zealand (RSNZ)
- Marsden Fund
- National Institute of General Medical Sciences (NIGMS) of the National Institutes of Health (NIH) [R35GM138348]
- University of Otago Doctoral Scholarship
- Cancer Prevention and Research Institute of Texas [RR160088]
- Bioprotection Aotearoa (Tertiary Education Commission, NZ)
This study reveals the specific binding ability of type I-D Cascade to ssRNA and the structural rearrangements initiated by PAM recognition of dsDNA targets. It also models how the anti-CRISPR protein blocks target dsDNA binding.
CRISPR-Cas systems are adaptive immune systems that protect prokaryotes from foreign nucleic acids, such as bacteriophages. Two of the most prevalent CRISPR-Cas systems include type I and type III. Interestingly, the type I-D interference proteins contain characteristic features of both type I and type III systems. Here, we present the structures of type I-D Cascade bound to both a double-stranded (ds)DNA and a single-stranded (ss)RNA target at 2.9 and 3.1 angstrom, respectively. We show that type I-D Cascade is capable of specifically binding ssRNA and reveal how PAM recognition of dsDNA targets initiates long-range structural rearrangements that likely primes Cas10d for Cas3 ' binding and subsequent non-target strand DNA cleavage. These structures allow us to model how binding of the anti-CRISPR protein AcrID1 likely blocks target dsDNA binding via competitive inhibition of the DNA substrate engagement with the Cas10d active site. This work elucidates the unique mechanisms used by type I-D Cascade for discrimination of single-stranded and double stranded targets. Thus, our data supports a model for the hybrid nature of this complex with features of type III and type I systems. I-D CRISPR-Cascade can target both single-stranded and double-stranded nucleic acids. Here, Schwartz et. al determine these structures and reveal large-scale rearrangements that allow for target discrimination and destruction.
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