PABP enhances release factor recruitment and stop codon recognition during translation termination

Area of Science:

• Molecular Biology
• Gene Expression Regulation

Background:

• Poly(A)-binding protein (PABP) is a key component of messenger ribonucleoprotein complexes.
• PABP interacts with mRNA poly(A) tails, translation initiation factors, and release factors.
• Previous research indicates PABP stimulates translation initiation and inhibits nonsense-mediated mRNA decay.

Purpose of the Study:

• To investigate the direct role of PABP in translation termination.
• To elucidate the mechanism by which PABP influences translation termination efficiency.

Main Methods:

• Utilized a reconstituted mammalian in vitro translation system.
• Examined the recruitment of eukaryotic release factor 1 (eRF1) and eukaryotic release factor 3a (eRF3a) to the ribosome.
• Investigated the functional differences between full-length eRF3a and its truncated form, eRF3c.

Main Results:

• PABP directly stimulates translation termination by promoting the recruitment of eRF1 and eRF3a to the ribosome.
• PABP's function in termination is dependent on its C-terminal domain and interaction with the N-terminus of eRF3a.
• Full-length eRF3a, but not eRF3c, significantly enhances peptidyl-tRNA hydrolysis when pre-associated with pre-termination complexes, suggesting additional interactions.

Conclusions:

• PABP enhances translation termination by facilitating the productive binding of the eRF1-eRF3 complex to the ribosome.
• The N-terminal domain of eRF3a plays an active role in translation termination, interacting with PABP and the ribosome.
• PABP's role extends beyond translation initiation to actively participate in translation termination regulation.