Co-evolution of spliceosomal disassembly interologs: crowning J-protein component with moonlighting RNA-binding activity
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Spliceosome disassembly is catalyzed by the NineTeen-related (NTR) complex, which is constituted by several proteins, including Cwc23, Ntr1, and Ppr43. Cwc23 is an essential J-protein in Saccharomyces cerevisiae that recruits Ntr1, an NTC-related G-patch protein, to the spliceosome. Ntr1 interacts with Prp43, a DExD/H box RNA helicase protein, which facilitates the disassembly of spliceosomal intermediates. The interaction between Ntr1 and Prp43 is conserved and crucial for the disassembly process. However, the J-protein component of this complex is not studied in other eukaryotes. In silico analysis supported by results of yeast complementation and two-hybrid studies suggests that while Prp43 is highly conserved, both Ntr1 and Cwc23 are co-evolving components of the disassembly triad. The J-domain of Cwc23, which is otherwise dispensable for its function, is highly conserved, whereas the functionally critical C-terminus has significantly diverged in Cwc23 orthologs. Some eukaryotic orthologs of Cwc23 contain a distinct RNA recognition motif at their C-terminus and are able to bind RNA in vitro. Based on the results presented in this study, we propose that RNA-binding activity in some eukaryotic orthologs of Cwc23 might provide additional functional diversity or robustness to the J-protein/Hsp70 machine in spliceosomal remodelling processes.
KeywordsJ-proteins S. cerevisiae K. lactis S. pombe Spliceosome Co-evolution RRM
We would like to thank Prof. Elizabeth Craig (University of Wisconsin–Madison), and Prof. R.S. Tomar (Indian Institute of Science Education and Research, Bhopal) for yeast strains, plasmids, and antibodies. We thank C.S. lab members for critical comments. We thank the reviewers for their valuable suggestions which really helped in improving this manuscript. S.R. and A.K.V. thank the Indian Ministry of Human Resource Development for a Graduate Aptitude Test in Engineering fellowship; K.Y. and Y.T. thank Council of Scientific and Industrial Research, Government of India, for fellowship. This work was supported by project grants from the Department of Biotechnology (BT/PR12149/BRB/10/1348/2014), Government of India to C.S. We thank IISER Bhopal for intramural funds and the Central Instrumentation Facility.
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