Distinct functions for the paralogous RBM41 and U11/U12-65K proteins in the minor spliceosome

AJ Norppa; I Chowdhury; LE van Rooijen; JJ Ravantti; B Snel; M Varjosalo; MJ Frilander

doi:10.1093/nar/gkae070

Distinct functions for the paralogous RBM41 and U11/U12-65K proteins in the minor spliceosome

AJ Norppa, I Chowdhury, LE van Rooijen, JJ Ravantti, B Snel, M Varjosalo, MJ Frilander^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Here, we identify RBM41 as a novel unique protein component of the minor spliceosome. RBM41 has no previously recognized cellular function but has been identified as a paralog of U11/U12-65K, a known unique component of the U11/U12 di-snRNP. Both proteins use their highly similar C-terminal RRMs to bind to 3′-terminal stem-loops in U12 and U6atac snRNAs with comparable affinity. Our BioID data indicate that the unique N-terminal domain of RBM41 is necessary for its association with complexes containing DHX8, an RNA helicase, which in the major spliceosome drives the release of mature mRNA from the spliceosome. Consistently, we show that RBM41 associates with excised U12-type intron lariats, is present in the U12 mono-snRNP, and is enriched in Cajal bodies, together suggesting that RBM41 functions in the post-splicing steps of the minor spliceosome assembly/disassembly cycle. This contrasts with U11/U12-65K, which uses its N-terminal region to interact with U11 snRNP during intron recognition. Finally, while RBM41 knockout cells are viable, they show alterations in U12-type 3′ splice site usage. Together, our results highlight the role of the 3′-terminal stem-loop of U12 snRNA as a dynamic binding platform for the U11/U12-65K and RBM41 proteins, which function at distinct stages of the assembly/disassembly cycle.

Original language	English
Article number	gkae070
Pages (from-to)	4037-4052
Number of pages	16
Journal	Nucleic Acids Research
Volume	52
Issue number	7
Early online date	18 Mar 2024
DOIs	https://doi.org/10.1093/nar/gkae070
Publication status	Published - 24 Apr 2024

Bibliographical note

Publisher Copyright:
© The Author(s) 2024.

Funding

Sigrid Juselius Foundation [to M.J.F and M.V.]; Academy of Finland [308657 and 1341477 to M.J.F.]; Jane and Aatos Erkko Foundation [to M.J.F]; Biocentrum Finland and Helsinki Institute of Life Sciences (HiLIFE) infrastructure funding [to M.V.]; Netherlands Organisation for Scientific Research (NWO) [VICI program, grant 016.160.638 to B.S.]; A.J.N. was supported by the Integrative Life Science doctoral program at the University of Helsinki. Funding for open access charge: Helsinki University Library.

Funders	Funder number
Jane ja Aatos Erkon Säätiö
University of Helsinki Life Science Research Infrastructures
Helsingin Yliopisto
Helsinki University Library
Biocenter Finland
Helsinki Institute of Life Sciences
Sigrid Juséliuksen Säätiö
Research Council of Finland	308657, 1341477
Nederlandse Organisatie voor Wetenschappelijk Onderzoek	016.160.638

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gkae070Final published version, 3.01 MBLicence: CC BY

Cite this

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Distinct functions for the paralogous RBM41 and U11/U12-65K proteins in the minor spliceosome

Abstract

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Funding

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