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  • 09월 03일 23시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제122회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Structures and interactions of anti-CRISPR proteins

2018년 9월 3일 14시 42분 26초
LIFE2-5 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
금 10시 : 40분
Life Chemistry - Recent Trends in Genome Editing Technique
저자 및
Euiyoung Bae
Department of Agricultural Biotechnology, Seoul National University, Korea
Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins provide bacterial adaptive immunity against bacteriophage infection. To counteract this defense mechanism, bacteriophages evolved anti-CRISPR (Acr) proteins that inactivate the antiphage CRISPR-Cas systems. Here, we report the crystal structures of two Acr proteins, AcrF2 and AcrIIA1. AcrF2 inhibits the type I-F CRISPR-Cas system in Pseudomonas aeruginosa. In this type, multiple Cas proteins (Csy1–4) comprise a surveillance complex (Csy complex) with CRISPR RNA (crRNA) for target recognition. AcrF2 binds to the Csy1-Csy2 heterodimers with nanomolar affinity. In the crystal structure of AcrF2, the arrangement of carboxyl side chains resembles the negative charge distribution of the dsDNA backbone, confirming that AcrF2 is a double-stranded DNA mimic blocking target recognition. AcrIIA1, encoded by Listeria monocytogenes prophages, is the most prevalent among the Acr proteins targeting type II-A CRISPR-Cas systems. AcrIIA1 forms a dimer with a novel two helical-domain architecture. The N-terminal domain of AcrIIA1 exhibits a helix-turn-helix motif similar to transcriptional factors. When overexpressed in Escherichia coli, AcrIIA1 associates with RNAs, suggesting that AcrIIA1 functions via nucleic acid recognition. Taken together, the structural and functional features of AcrF2 and AcrIIA1 suggest their distinct modes of Acr activity, expanding the diversity of the inhibitory mechanisms employed by Acr proteins.