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![[Figure 1]](jc5035fig1mag.jpg)
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Figure 1
Bioinformatic analysis of Rsm22-family proteins. (a) Predicted domain structure of the Rsm22 family. The SAM-binding domain and substrate-binding domain together comprise a Rossmann-like SAM-MTase fold, which is located in the middle. The N-termini are highly variable. There is an extended N-terminal domain preceding the SAM-binding domain in Tb-Rsm22. The N-terminal domain is absent in Hs-METTL17 isoforms X1 and X2. The C-terminal domain is also variable between the family members, being shortest in Hs-METTL17, but contains a relatively conserved OB-motif in all family members. (b) Sequence alignment of S. cerevisiae Rsm22 (Sc-Rsm22) with Rsm22 from T. brucei (Tb-Rsm22) and METTL17 from mouse (Mm-METTL17) and human (Hs-METTL17). The predicted secondary-structure elements of Sc-Rsm22 are shown above the sequence, with rectangles representing α-helices and arrows representing β-strands. The shaded secondary elements are those with the highest probabilities, and the prediction is based on analysis using the Phyre2 server (Kelley et al., 2015  ; https://www.sbg.bio.ic.ac.uk/~phyre2/html/page.cgi?id=index) and on sequence comparison with Tb-Rsm22, the structure of which was determined by cryo-EM (Saurer et al., 2019). The elements shown with dotted lines are only based on the amino-acid sequence-based prediction (by the Phyre2 server). The star (![[\star]](teximages/jc5035fi1.svg) ) indicates the end of the predicted mitochondrial targeting sequence of Sc-Rsm22. The MTase core fold consists of α-helices Z, A, B, C, D and E and β-strands 1–7. β-Strands 6b and 7b are unique to the Rsm22 family of methyltransferases and include the zinc-finger structure motif (zinc-binding residues are highlighted with yellow dots). The glycine-rich SAM-binding motif is also emphasized with a red line below the sequences, and the important glycines are indicated by red dots above the sequences. The positively charged residues which interact with rRNA in the T. brucei mitoribosome complex (Saurer et al., 2019) are highlighted with red open squares in the Tb-Rsm22 sequence. An OB-fold is observed in the C-terminus of Tb-Rsm22 and is also predicted to be present in other members of the protein family. |
![[Figure 1]](jc5035fig1.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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