Allosteric regulation of Csx1, a type IIIB-associated CARF domain ribonuclease by RNAs carrying a tetraadenylate tail.
Nucleic Acids Res
; 45(18): 10740-10750, 2017 Oct 13.
Article
in En
| MEDLINE
| ID: mdl-28977519
ABSTRACT
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 (CRISPR-associated 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 the HEPN 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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
RNA, Messenger
/
Sulfolobus
/
Archaeal Proteins
/
Endoribonucleases
Type of study:
Risk_factors_studies
Language:
En
Journal:
Nucleic Acids Res
Year:
2017
Type:
Article
Affiliation country:
Denmark