Jung Kyoon Choi1
& Young-Joon Kim1
Variation in gene expression is an essential material for biological diversity among single cells1, 2, 3
, individuals4, 5, 6
and populations or species7, 8, 9
. Here we show that expression variability is an intrinsic property that persists at those different levels. Each promoter seems to have a unique capacity to respond to external signals that can be environmental, genetic or even stochastic. Our investigation into nucleosome organization of variably responding promoters revealed a commonly positioned nucleosome at a critical regulatory region where most transcription start sites and TATA elements are located, a deviation from typical nucleosome-free status. The nucleotide sequences in this region of variable promoters showed a high propensity for DNA bending and a periodic distribution of particular dinucleotides, encoding preferences for DNA-nucleosome interaction. Variable expression is likely to occur during removal of this nucleosome for gene activation. This is a unique example of how promoter sequences intrinsically encode regulatory flexibility, which is vital for biological processes such as adaptation, development and evolution.
1. Department of Biochemistry, Yonsei University, Seodaemun-gu, Seoul, Korea.
Correspondence to: Young-Joon Kim1