Antisense pairing and SNORD13 structure guide RNA cytidine acetylation

Area of Science:

• Molecular Biology
• RNA Biology
• Biochemistry

Background:

• N4-acetylcytidine (ac4C) is a conserved RNA modification found across all life domains.
• The acetylation of helix 45 (h45) in human 18S ribosomal RNA (rRNA) depends on NAT10 and SNORD13.
• Mechanisms of RNA-guided nucleobase acetylation in humans are not well understood.

Purpose of the Study:

• To explore the molecular mechanisms of SNORD13-guided RNA acetylation in human cells.
• To develop novel assays for studying SNORD13-dependent RNA acetylation.
• To identify critical structure and sequence elements for SNORD13 function in acetylation.

Main Methods:

• Comparative sequence analysis and site-directed mutagenesis of SNORD13.
• Development of two assays for studying RNA acetylation in human cells.
• Nucleotide-resolution ac4C sequencing and mutational analysis of pre-rRNA substrates.

Main Results:

• SNORD13 folds into three major RNA helices.
• Ectopic SNORD13 expression rescues h45 modification in knockout cells.
• Identified plasticity in molecular determinants for RNA-guided cytidine acetylation, distinct from other rRNA modifications.

Conclusions:

• Established novel methods to reconstitute and study RNA-guided cytidine acetylation in human cells.
• Provided nucleotide-resolution insights into the mechanisms of ac4C deposition.
• Demonstrated that RNA-guided acetylation mechanisms exhibit plasticity compared to other rRNA modifications.