Crystal Structure of the S. solfataricus Archaeal Exosome Reveals Conformational Flexibility in the RNA-Binding Ring |
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Authors: | Changrui Lu Fang Ding Ailong Ke |
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Institution: | Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America.;University of Oulu, Finland |
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Abstract: | BackgroundThe 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 FindingsHere we report an asymmetric 2.9 Å 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/SignificanceThis study clearly shows the dynamic structures within the RNA-binding domains, which provides additional insights on mechanism of asymmetric RNA binding and processing. |
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