Crystal structure of the S. solfataricus archaeal exosome reveals conformational flexibility in the RNA-binding ring.
basic_science · Level V
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- Record sourced from PubMed, PMID 20090900.
- Also identified by DOI 10.1371/journal.pone.0008739 and PMC identifier PMC311015.
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Abstract
BACKGROUND: The exosome complex is an essential RNA 3'-end processing and degradation machinery. In archaeal organisms, the exosome consists of a catalytic ring and an RNA-binding ring, both of which were previously reported to assume three-fold symmetry. METHODOLOGY/PRINCIPAL FINDINGS: Here we report an asymmetric 2.9 A Sulfolobus solfataricus archaeal exosome structure in which the three-fold symmetry is broken due to combined rigid body and thermal motions mainly within the RNA-binding ring. Since increased conformational flexibility was also observed in the RNA-binding ring of the related bacterial PNPase, we speculate that this may reflect an evolutionarily conserved mechanism to accommodate diverse RNA substrates for degradation. CONCLUSION/SIGNIFICANCE: This study clearly shows the dynamic structures within the RNA-binding domains, which provides additional insights on mechanism of asymmetric RNA binding and processing.