title: Structural Insights into a Unique Dimeric DEAD-Box Helicase CshA that Promotes RNA Decay.
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.
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Huen
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC.
authors.forename: Chia-Liang
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC; Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan 11529, ROC; Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC.
authors.forename: Bagher
authors.initials: B
authors.lastname: Golzarroshan
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC.
authors.forename: Wan-Li
authors.initials: WL
authors.lastname: Yi
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC.
authors.forename: Wei-Zen
authors.initials: WZ
authors.lastname: Yang
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, ROC; Graduate Institute of Biochemistry and Molecular Biology, National Taiwan University, Taipei, Taiwan 10048, ROC. Electronic address: hanna@sinica.edu.tw.
authors.forename: Hanna S
authors.initials: HS
authors.lastname: Yuan
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D053487:DEAD-box RNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D005095:Exoribonucleases / Q000378:metabolism; D001411:Geobacillus stearothermophilus / Q000378:metabolism*; D006868:Hydrolysis; D008958:Models, Molecular; D055503:Protein Multimerization; D012313:RNA / Q000378:metabolism*; D020871:RNA Stability; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D012313:RNA; D000255:Adenosine Triphosphate; D005095:Exoribonucleases; D053487:DEAD-box RNA Helicases
keywords: ATP hydrolysis; DEAD-box helicase; RNA decay; RNA turnover; crystal structure