Translation rate modification by preferential codon usage: intragenic position effects

Area of Science:

• Molecular Biology
• Biophysics
• Computational Biology

Background:

• Protein production rate is crucial for cellular function.
• Ribosome translation speed varies along mRNA due to codon usage and tRNA availability.
• Synonymous codon choice may be influenced by selective pressures, particularly near the mRNA initiation site.

Purpose of the Study:

• To develop a model for calculating protein production rate based on translation speed.
• To investigate how mRNA sequence and ribosome elongation rates influence the production of abundant versus rare proteins.
• To analyze codon distribution patterns in mRNAs encoding proteins of varying abundance.

Main Methods:

• Development of a computational model linking translation elongation rates to protein production.
• Analysis of non-uniform ribosome elongation rates along mRNA, considering tRNA availability.
• Examination of codon distribution in known mRNA sequences for abundant and rare proteins.

Main Results:

• The model demonstrates that elongation rate along the entire mRNA impacts abundant protein production.
• For rare proteins, only the elongation rate within the mRNA initiation region is critical for production.
• Distinct codon distribution patterns were observed between mRNAs for abundant and rare proteins.

Conclusions:

• The rate-limiting step in protein synthesis is influenced by mRNA sequence and protein abundance.
• Selective pressures on synonymous codons differ between mRNA initiation sites and other regions.
• Understanding these dynamics is key to predicting and controlling protein production.