# Gene length as a regulator for ribosome recruitment and protein synthesis: theoretical insights

## TL;DR

This paper presents a theoretical model showing how transcript length influences ribosome recruitment and protein synthesis efficiency, highlighting a potential feedback mechanism that cells may use to optimize resource utilization.

## Contribution

It introduces a novel theoretical framework linking mRNA length to translation regulation, emphasizing the role of transcript length in ribosome recycling and gene expression control.

## Key findings

- Transcript length affects ribosome recruitment and translation rates.
- Proximity of mRNA ends can create a feedback loop for ribosome recycling.
- Cells may exploit length-dependent mechanisms to balance ribosomal resources.

## Abstract

Protein synthesis rates are determined, at the translational level, by properties of the transcript's sequence. The efficiency of an mRNA can be tuned by varying the ribosome binding sites controlling the recruitment of the ribosomes, or the codon usage establishing the speed of protein elongation. In this work we propose transcript length as a further key determinant of translation efficiency. Based on a physical model that considers the kinetics of ribosomes advancing on the mRNA and diffusing in its surrounding, as well as mRNA circularisation and ribosome drop-off, we explain how the transcript length may play a central role in establishing ribosome recruitment and the overall translation rate of an mRNA. According to our results, the proximity of the 3' end to the ribosomal recruitment site of the mRNA could induce a feedback in the translation process that would favour the recycling of ribosomes. We also demonstrate how this process may be involved in shaping the experimental ribosome density-gene length dependence. Finally, we argue that cells could exploit this mechanism to adjust and balance the usage of its ribosomal resources.