Download MendeleyStructural Insights into a Unique Dimeric DEAD-Box Helicase CshA that Promotes RNA Decay.
Huen, J., Lin, C.-L., Golzarroshan, B., Yi, W.-L., Yang, W.Z., Yuan, H.S.(2017) Structure 25: 469-481
- PubMed: 28238534
- DOI: https://doi.org/10.1016/j.str.2017.01.012
- Primary Citation of Related Structures:
5IVL - PubMed Abstract:
CshA is a dimeric DEAD-box helicase that cooperates with ribonucleases for mRNA turnover. The molecular mechanism for how a dimeric DEAD-box helicase aids in RNA decay remains unknown. Here, we report the crystal structure and small-angle X-ray scattering solution structure of the CshA from Geobacillus stearothermophilus. In contrast to typical monomeric DEAD-box helicases, CshA is exclusively a dimeric protein with the RecA-like domains of each protomer forming a V-shaped structure. We show that the C-terminal domains protruding outward from the tip of the V-shaped structure is critical for mediating strong RNA binding and is crucial for efficient RNA-dependent ATP hydrolysis. We also show that RNA remains bound with CshA during ATP hydrolysis cycles and thus bulk RNAs could be unwound and degraded in a processive manner through cooperation between exoribonucleases and CshA. A dimeric helicase is hence preserved in RNA-degrading machinery for efficient RNA turnover in prokaryotes and eukaryotes.
Organizational Affiliation:
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC.
