6b91
From Proteopedia
Crystal structure of the N-terminal domain of human METTL16
Structural highlights
Function[MET16_HUMAN] RNA N6-methyltransferase that methylates adenosine residues of a subset of RNAs and plays a key role in S-adenosyl-L-methionine homeostasis by regulating expression of MAT2A transcripts (PubMed:28525753). Able to N6-methylate a subset of mRNAs and U6 small nuclear RNAs (U6 snRNAs) (PubMed:28525753). In contrast to the METTL3-METTL14 heterodimer, only able to methylate a limited number of RNAs: requires both a 5'UACAGAGAA-3' nonamer sequence and a specific RNA structure (PubMed:28525753). In presence of S-adenosyl-L-methionine, binds the 3'-UTR region of MAT2A mRNA and specifically N6-methylates the first hairpin of MAT2A mRNA, impairing MAT2A expression (PubMed:28525753). In S-adenosyl-L-methionine-limiting conditions, binds the 3'-UTR region of MAT2A mRNA but stalls due to the lack of a methyl donor, preventing N6-methylation and promoting expression of MAT2A (PubMed:28525753). In addition to mRNAs, also able to mediate N6-methylation of U6 small nuclear RNA (U6 snRNA): specifically N6-methylates adenine in position 43 of U6 snRNAs (PubMed:28525753, PubMed:29051200). Also able to bind various lncRNAs (PubMed:29051200). Specifically binds the 3'-end of the MALAT1 long non-coding RNA (PubMed:27872311).[1] [2] [3] Publication Abstract from PubMedN(6)-methyladenosine (m(6)A) is an abundant modification in messenger RNA and noncoding RNAs that affects RNA metabolism. Methyltransferase-like protein 16 (METTL16) is a recently confirmed m(6)A RNA methyltransferase that methylates U6 spliceosomal RNA and interacts with the 3'-terminal RNA triple helix of MALAT1 (metastasis-associated lung adenocarcinoma transcript 1). Here, we present two X-ray crystal structures of the N-terminal methyltransferase domain (residues 1-291) of human METTL16 (METTL16_291): an apo structure at 1.9 A resolution and a post-catalytic S-adenosylhomocysteine-bound complex at 2.1 A resolution. The structures revealed a highly conserved Rossmann fold that is characteristic of Class I S-adenosylmethionine-dependent methyltransferases and a large, positively charged groove. This groove likely represents the RNA-binding site and it includes structural elements unique to METTL16. In-depth analysis of the active site led to a model of the methyl transfer reaction catalyzed by METTL16. In contrast to the major m(6)A methyltransferase heterodimer METTL3/METTL14, full-length METTL16 forms a homodimer and METTL16_291 exists as a monomer based on size-exclusion chromatography. A native gel-shift assay shows that METTL16 binds to the MALAT1 RNA triple helix, but monomeric METTL16_291 does not. Our results provide insights into the molecular structure of METTL16, which is distinct from METTL3/METTL14. Structural insights into the RNA methyltransferase domain of METTL16.,Ruszkowska A, Ruszkowski M, Dauter Z, Brown JA Sci Rep. 2018 Mar 28;8(1):5311. doi: 10.1038/s41598-018-23608-8. PMID:29593291[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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