Control of box C/D snoRNP assembly by N(6)-methylation of adenine.
Huang, L., Ashraf, S., Wang, J., Lilley, D.M.(2017) EMBO Rep 18: 1631-1645
- PubMed: 28623187 
- DOI: https://doi.org/10.15252/embr.201743967
- Primary Citation of Related Structures:  
5LQO, 5LQT, 5LR3, 5LR4, 5LR5 - PubMed Abstract: 
N 6 -methyladenine is the most widespread mRNA modification. A subset of human box C/D snoRNA species have target GAC sequences that lead to formation of N 6 -methyladenine at a key trans Hoogsteen-sugar A·G base pair, of which half are methylated in vivo The GAC target is conserved only in those that are methylated. Methylation prevents binding of the 15.5-kDa protein and the induced folding of the RNA Thus, the assembly of the box C/D snoRNP could in principle be regulated by RNA methylation at its critical first stage. Crystallography reveals that N 6 -methylation of adenine prevents the formation of trans Hoogsteen-sugar A·G base pairs, explaining why the box C/D RNA cannot adopt its kinked conformation. More generally, our data indicate that sheared A·G base pairs (but not Watson-Crick base pairs) are more susceptible to disruption by N 6 mA methylation and are therefore possible regulatory sites. The human signal recognition particle RNA and many related Alu retrotransposon RNA species are also methylated at N6 of an adenine that forms a sheared base pair with guanine and mediates a key tertiary interaction.
Organizational Affiliation: 
Cancer Research UK Nucleic Acid Structure Research Group, The University of Dundee, Dundee, UK.