期刊
NUCLEIC ACIDS RESEARCH
卷 45, 期 18, 页码 10740-10750出版社
OXFORD UNIV PRESS
DOI: 10.1093/nar/gkx726
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资金
- Danish Council for Independent Research [DFF-060202196, DFF-1323-00330]
- Augustinus Foundation [153934]
- Brodrene Hartmanns Foundation [A29992]
- Natural Science Foundation of China [31128011]
- Scientific and Technological Self-Innovation Foundation of Huazhong Agricultural University [2014RC011]
- Novo Nordisk Foundation [NNF14CC0001]
- Danish Cancer Society
- University of Copenhagen
- Novo Nordisk Fonden [NNF17SA0024386] Funding Source: researchfish
- Novo Nordisk Foundation Center for Protein Research [PI Guillermo Montoya] Funding Source: researchfish
CRISPR-Cas systems protect prokaryotes against invading viruses and plasmids. The system is associated with a large number of Cas accessory proteins among which many contain a CARF (CRISPRassociated Rossmann fold) domain implicated in ligand binding and a HEPN (higher eukaryotes and prokaryotes nucleotide-binding) nuclease domain. Here, such a dual domain protein, i.e. the Sulfolobus islandicus Csx1 (SisCsx1) was characterized. The enzyme exhibited metal-independent single-strand specific ribonuclease activity. In fact, SisCsx1 showed a basal RNase activity in the absence of ligand; upon the binding of an RNA ligand carrying four continuous adenosines at the 3' end (3'-tetra-rA), the activated SisCsx1 degraded RNA substrate with a much higher turnover rate. Amino acid substitution mutants of SisCsx1 were obtained, and characterization of these mutant proteins showed that the CARF domain of the enzyme is responsible for binding to 3'-tetra-rA and the ligand binding strongly activates RNA cleavage by theHEPN domain. Since RNA polyadenylation is an important step in RNA decay in prokaryotes, and poly(A) RNAs can activate CARF domain proteins, the poly(A) RNA may function as an important signal in the cellular responses to viral infection and environmental stimuli, leading to degradation of both viral and host transcripts and eventually to cell dormancy or cell death.
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