Abstract
N6‐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 N6‐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 N6‐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 N6mA 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.
Highlights
All cellular RNA is subject to dynamic covalent modification, and posttranscriptional modification of RNA is diverse and widespread [1,2]
Results are shown for one box C/D k-turn from SNORD13 (U13) snoRNA, and one box C’/D’ k-turn from SNORD62A (U62A) snoRNA (Fig 4)
Over the same range of 15.5k protein concentration used in the electrophoresis, the fluorescence spectroscopy reveals an increase in energy transfer indicative of a folding of the k-turns (Fig 4B and D)
Summary
All cellular RNA is subject to dynamic covalent modification, and posttranscriptional modification of RNA is diverse and widespread [1,2]. N6-methyladenine is the most common modification in RNA [3,4,5] It is found in mRNA (a typical eukaryotic mRNA will have several such methylated adenine nucleotides), as well as in lncRNA species such as Xist [4,5] and MALAT1 [6,7]) and in viral RNA [8]. This epigenetic marker has proposed roles in the modulation of RNA stability [9], control of translation efficiency [10,11], and in gene regulation [12], and N6-methyladenine is most frequently observed in regions of mRNA indicative of control functions [5]. Watkins et al [30] showed that if the binding of 15.5k to the human box C/D k-turn is prevented by sequence changes that are known to disrupt k-turn folding, this blocks assembly of the box C/D snoRNP
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
