Central dogma at the single-molecule level in living cells

Area of Science:

• Molecular Biology
• Cell Biology
• Biophysics

Background:

• Gene expression, the process of converting genetic information into functional products, originates from individual DNA molecules.
• Single-molecule processes in cells, including gene expression and regulation, are inherently stochastic, occurring sporadically in time.
• This stochasticity leads to significant heterogeneity in messenger RNA (mRNA) and protein levels within a population of genetically identical cells.

Purpose of the Study:

• To investigate the stochastic nature of gene expression at the single-molecule level.
• To quantify dynamic molecular processes like transcription and translation in real time within single cells.
• To demonstrate the impact of single-molecule stochastic events on cellular phenotype.

Main Methods:

• Utilized advanced single-cell fluorescence microscopy techniques.
• Achieved single-molecule sensitivity for quantifying transcriptomes and proteomes.
• Monitored dynamic molecular processes including transcription-factor binding, transcription, and translation in real time.

Main Results:

• Successfully quantified mRNA and protein copy numbers with single-molecule resolution.
• Provided real-time quantitative descriptions of gene expression dynamics, adhering to the central dogma of molecular biology.
• Demonstrated that a single stochastic molecular event can be a determinant of a cell's phenotype.

Conclusions:

• Gene expression is fundamentally a stochastic process at the single-molecule level.
• Advanced microscopy enables real-time, quantitative analysis of molecular dynamics within single cells.
• Stochasticity in gene expression plays a crucial role in generating cellular heterogeneity and determining cell fate.