Counting mRNAs in living bacteria: the 2005 Golding paper that overturned the Poisson model of transcription
NikoMcCarty · x · 2026-11-03
Niko McCarty's long explainer on how gene transcription really works.
- Textbooks teach DNA → RNA → protein, but transcription is surprisingly unpredictable even in genetically identical cells.
- For decades biologists assumed transcription followed a Poisson process — a fixed per-step probability of producing an mRNA — largely because available methods were indirect proxies like inferring mRNA counts from GFP fluorescence, and mRNA/protein levels often don't correlate.
- He highlights Ido Golding et al.'s 2005 paper as one of modern biology's most beautiful: they engineered E. coli so GFP-fused MS2 coat proteins bind 96 MS2 sites on a target mRNA, forming bright puncta that could be calibrated to count individual transcripts in living cells, with IPTG-inducible timing to watch transcription unfold in real time.
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