Weak 5'-mRNA secondary structures in short eukaryotic genes

Area of Science:

• Molecular Biology
• Genetics
• Computational Biology

Background:

• Eukaryotic gene translation shows higher ribosome densities on short genes compared to long genes.
• The underlying cause for this difference—faster initiation or slower elongation—remains debated.

Purpose of the Study:

• To computationally investigate whether elevated ribosome density on short eukaryotic genes is due to differences in translation initiation or elongation rates.
• To use 5'-mRNA folding energy and codon bias as proxies for initiation and elongation rates, respectively.

Main Methods:

• Computational analysis of 5'-mRNA folding energy to estimate translation initiation rates.
• Analysis of codon bias as a proxy for translation elongation rates.
• Comparison of these metrics between short and long coding sequences across diverse eukaryotic taxa.

Main Results:

• Shorter coding sequences exhibit a significant trend toward reduced 5'-secondary structures, indicating faster translation initiation.
• Short genes also show a trend toward higher 5'-codon bias, suggesting faster elongation rates.
• These trends were consistently observed across various eukaryotic species.

Conclusions:

• The higher ribosome density observed on short eukaryotic genes is primarily attributed to faster translation initiation rates.
• Differential elongation rates do not appear to be the main driver for increased ribosome density on short genes.
• Findings provide insight into the regulatory mechanisms of gene expression in eukaryotes.