Quantifying Single mRNA Translation Kinetics in Living Cells.

Area of Science:

• Molecular Biology
• Cell Biology
• Biophysics

Background:

• The central dogma of molecular biology, describing gene expression from DNA to RNA to protein, has been challenging to fully quantify at the single-molecule level in living cells.
• Specifically, imaging the translation of single messenger RNA (mRNA) molecules has remained a significant hurdle.

Purpose of the Study:

• To describe recent advances in protein tagging and imaging technologies for visualizing and quantifying single mRNA translation in living cells.
• To highlight the application of repeat-epitope tags for detailed analysis of translation dynamics.

Main Methods:

• Utilizing advanced protein tagging, specifically repeat-epitope tags, to label nascent polypeptide chains.
• Employing high-resolution live-cell imaging techniques to visualize and quantify single mRNA translation events.
• Integrating complementary assays, including fast-maturing fluorophores and mRNA-binding protein knockoff, to monitor translation dynamics.

Main Results:

• Precise visualization and quantification of nascent polypeptide synthesis from single mRNA molecules.
• Enabled quantification of single mRNA ribosomal densities, translation initiation and elongation rates.
• Revealed insights into translation site mobility and higher-order structure.
• Uncovered striking and unexpected heterogeneity in gene expression at the translation level.

Conclusions:

• Recent technological advancements, particularly in protein tagging and imaging, are overcoming previous limitations in studying single mRNA translation.
• These single-molecule studies are beginning to reveal complex and previously unrecognized heterogeneity in gene expression during translation.
• This work provides a foundation for deeper understanding of translational control and its role in cellular function.