G-quadruplexes: the beginning and end of UTRs

Area of Science:

• Molecular Biology
• Genetics
• Bioinformatics

Background:

• Gene expression is regulated by molecular mechanisms occurring before or after transcription.
• Post-transcriptional regulation relies on RNA sequence and structure.
• G-quadruplex (G4) motifs are proposed to influence both transcription and translation.

Purpose of the Study:

• To investigate the occurrence and distribution of G-quadruplex motifs within and around the untranslated regions (UTRs) of messenger RNA (mRNA).
• To explore the potential roles of G-quadruplexes in translational control and transcription termination.

Main Methods:

• Bioinformatic analysis of G-quadruplex motifs in mRNA untranslated regions.
• Examination of strand asymmetry and positional bias of G-quadruplex motifs.
• Correlation of G-quadruplex distribution with gene proximity and UTR regions.

Main Results:

• A significant strand asymmetry was observed, indicating a general depletion of G-quadruplex-forming RNA.
• A positional bias of G-quadruplex motifs was identified in specific regions of UTRs.
• An excess of G-quadruplex motifs was found towards the 5'-ends of 5'-UTRs, supporting a role in translational control.
• An over-representation of G-quadruplex motifs was observed immediately after the 3'-end of genes, particularly when genes are in close proximity, suggesting involvement in transcription termination.

Conclusions:

• G-quadruplex motifs exhibit specific distribution patterns in mRNA untranslated regions.
• 5'-UTR G-quadruplexes are linked to translational control.
• G-quadruplexes near 3'-ends of genes may play a role in transcription termination.