University of Oulu

Alam, J., Rahman, F. T., Sah-Teli, S. K., Venkatesan, R., Koski, M. K., Autio, K. J., Hiltunen, J. K., & Kastaniotis, A. J. (2021). Expression and analysis of the SAM-dependent RNA methyltransferase Rsm22 from Saccharomyces cerevisiae. Acta Crystallographica Section D Structural Biology, 77(6), 840–853.

Expression and analysis of the SAM-dependent RNA methyltransferase Rsm22 from Saccharomyces cerevisiae

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Author: Alam, Jahangir1; Rahman, Farah Tazkera1; Sah-Teli, Shiv K.1;
Organizations: 1Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7B, FIN-90220 Oulu, Finland
2Biocenter Oulu, Aapistie 5A, FIN-90220 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: International Union of Crystallography, 2021
Publish Date: 2021-05-27


The Saccharomyces cerevisiae Rsm22 protein (Sc-Rsm22), encoded by the nuclear RSM22 (systematic name YKL155c) gene, is a distant homologue of Rsm22 from Trypanosoma brucei (Tb-Rsm22) and METTL17 from mouse (Mm-METTL17). All three proteins have been shown to be associated with mitochondrial gene expression, and Sc-Rsm22 has been documented to be essential for mitochondrial respiration. The Sc-Rsm22 protein comprises a polypeptide of molecular weight 72.2 kDa that is predicted to harbor an N-terminal mitochondrial targeting sequence. The precise physiological function of Rsm22-family proteins is unknown, and no structural information has been available for Sc-Rsm22 to date. In this study, Sc-Rsm22 was expressed and purified in monomeric and dimeric forms, their folding was confirmed by circular-dichroism analyses and their low-resolution structures were determined using a small-angle X-ray scattering (SAXS) approach. The solution structure of the monomeric form of Sc-Rsm22 revealed an elongated three-domain arrangement, which differs from the shape of Tb-Rsm22 in its complex with the mitochondrial small ribosomal subunit in T. brucei (PDB entry 6sg9). A bioinformatic analysis revealed that the core domain in the middle (Leu117–Asp462 in Sc-Rsm22) resembles the corresponding region in Tb-Rsm22, including a Rossmann-like methyltransferase fold followed by a zinc-finger-like structure. The latter structure is not present in this position in other methyltransferases and is therefore a unique structural motif for this family. The first half of the C-terminal domain is likely to form an OB-fold, which is typically found in RNA-binding proteins and is also seen in the Tb-Rsm22 structure. In contrast, the N-terminal domain of Sc-Rsm22 is predicted to be fully α-helical and shares no sequence similarity with other family members. Functional studies demonstrated that the monomeric variant of Sc-Rsm22 methylates mitochondrial tRNAs in vitro. These data suggest that Sc-Rsm22 is a new and unique member of the RNA methyltransferases that is important for mitochondrial protein synthesis.

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Series: Acta Crystallographica. Section D, Structural biology
ISSN: 2059-7983
ISSN-E: 2059-7983
ISSN-L: 2059-7983
Volume: 77
Issue: 6
Pages: 840 - 853
DOI: 10.1107/S2059798321004149
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: This work was financially supported by the Sigrid Juselius foundation, the Academy of Finland and Biocenter Oulu,Finland.
Copyright information: © 2021 The Authors. This is an open access article under the CC BY license (