Research led by Duke University, Durham, has discovered a situation-dependent traffic jam in mRNA translation caused by RNA hairpins leading to higher translation of upstream start codons (uAUGs).
In a paper, “Pervasive downstream RNA hairpins dynamically dictate start-codon selection,” published in Nature, the team describes their findings of a translational regulation mechanism in the plant Arabidopsis and consequent discovery of a similar mechanism in humans. A News & Views piece in the same journal issue discussed the work done by the team.
Any genome is constructed with instructions that inform when to start and stop the transcription of RNA segments. These segments can contain multiple start codons, which can then be selectively used as beginning points for the ribosome to start translating them into proteins. The current study has identified a mechanism by which the selection process between potential starting points takes place.
Ribosomal subunits assemble on an mRNA molecule and scan it for the AUG start codon to initiate protein synthesis. Sometimes, the first start codon encountered is used as initiation, and sometimes, it is not recognized. If it is not recognized, the scanning continues down the mRNA, where it may find an alternative starting point or a more easily recognized starting point (the main AUG).
The study discovered that if the mRNA has a hairpin loop located between two starting codons, the scanning process will be slowed down, providing more time for recognition of the upstream start codon (uAUG), leading to a higher translation rate from this starting point.
2023-09-09 00:48:02
Article from phys.org