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The structure of AcrIC9 revealing the putative inhibitory mechanism of AcrIC9 against the type IC CRISPR–Cas system

Authors :
Yong Jun Kang
Ju Hyeong Kim
Gwan Hee Lee
Hyun Ji Ha
Young-Hoon Park
Eunmi Hong
Hyun Ho Park
Source :
IUCrJ, Vol 10, Iss 5, Pp 624-634 (2023)
Publication Year :
2023
Publisher :
International Union of Crystallography, 2023.

Abstract

CRISPR–Cas systems are known to be part of the bacterial adaptive immune system that provides resistance against intruders such as viruses, phages and other mobile genetic elements. To combat this bacterial defense mechanism, phages encode inhibitors called Acrs (anti-CRISPR proteins) that can suppress them. AcrIC9 is the most recently identified member of the AcrIC family that inhibits the type IC CRISPR–Cas system. Here, the crystal structure of AcrIC9 from Rhodobacter capsulatus is reported, which comprises a novel fold made of three central antiparallel β-strands surrounded by three α-helixes, a structure that has not been detected before. It is also shown that AcrIC9 can form a dimer via disulfide bonds generated by the Cys69 residue. Finally, it is revealed that AcrIC9 directly binds to the type IC cascade. Analysis and comparison of its structure with structural homologs indicate that AcrIC9 belongs to DNA-mimic Acrs that directly bind to the cascade complex and hinder the target DNA from binding to the cascade.

Details

Language :
English
ISSN :
20522525
Volume :
10
Issue :
5
Database :
Directory of Open Access Journals
Journal :
IUCrJ
Publication Type :
Academic Journal
Accession number :
edsdoj.4a7605c5190743449e253ae0c5193755
Document Type :
article
Full Text :
https://doi.org/10.1107/S2052252523007236