RNA processing by the CRISPR-associated NYN ribonuclease
Abstract
CRISPR-Cas systems confer adaptive immunity in prokaryotes, facilitating the recognition and destruction of invasive nucleic acids. Type III CRISPR systems comprise large, multisubunit ribonucleoprotein complexes with a catalytic Cas10 subunit. When activated by the detection of foreign RNA, Cas10 generates nucleotide signalling molecules that elicit an immune response by activating ancillary effector proteins. Among these systems, the Bacteroides fragilis type III CRISPR system was recently shown to produce a novel signal molecule, SAM-AMP, by conjugating ATP and SAM. SAM-AMP regulates a membrane effector of the CorA family to provide immunity. Here, we focus on NYN, a ribonuclease encoded within this system, probing its potential involvement in crRNA maturation. Structural modelling and in vitro ribonuclease assays reveal that NYN displays robust sequence-nonspecific, Mn2+-dependent ssRNA-cleavage activity. Our findings suggest a role for NYN in trimming crRNA intermediates into mature crRNAs, which is necessary for type III CRISPR antiviral defence. This study sheds light on the functional relevance of CRISPR-associated NYN proteins and highlights the complexity of CRISPR-mediated defence strategies in bacteria.
Citation
Chi , H & White , M 2024 , ' RNA processing by the CRISPR-associated NYN ribonuclease ' , Biochemical Journal , vol. 481 , no. 12 , pp. 793–804 . https://doi.org/10.1042/BCJ20240151
Publication
Biochemical Journal
Status
Peer reviewed
ISSN
0264-6021Type
Journal article
Description
Funding: EC | European Research Council (ERC) - 101018608; China Scholarship Council (CSC) - 202008420207.Collections
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