Blurred Boundaries Between Coding and Noncoding RNAs: Insights From Phage-bacteria Interactions.

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The RNA world hypothesis posits RNA's ancestral dual role in catalysis and genetic information.
• Proteins have largely supplanted RNA in cellular functions, yet RNAs persist in regulatory roles and as functional relics.
• Dual-function RNAs represent a novel class with both regulatory (noncoding) and protein-coding capabilities.

Purpose of the Study:

• To review recent discoveries in the functional interplay between coding and noncoding sequences.
• To highlight the evolving understanding of RNA and small protein roles in bacterial defense against phages.
• To explore emerging mechanisms challenging established notions of genetic function.

Main Methods:

• Computational approaches for sequence analysis.
• Experimental techniques like ribosome profiling.
• Cryo-electron microscopy for structural elucidation.

Main Results:

• Discovery of diverse very short proteins and highly structured RNAs.
• Identification of novel antiphage defense systems utilizing non-canonical coding from ncRNAs.
• Observation of ncRNAs and small proteins forming supramolecular complexes for defense.
• Evidence for de novo gene birth from noncoding sequences and ncRNA emergence from coding sequences.

Conclusions:

• The boundaries between coding and noncoding sequences are increasingly blurred.
• Small proteins and ncRNAs play critical, often overlapping, roles in bacteria-phage interactions.
• Emerging mechanisms expand the known functional repertoire of RNA and protein sequences.