Chromatin—a global buffer for eukaryotic gene control

Yuri M. Moshkin ^{1,2
,
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1.
Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk 630090, Russia
2.
Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk 630090, Russia

Received: 26 August 2015 Accepted: 20 September 2015 Published: 22 September 2015

Abstract
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Most of eukaryotic DNA is embedded into nucleosome arrays formed by DNA wrapped around a core histone octamer. Nucleosome is a fundamental repeating unit of chromatin guarding access to the genetic information. Here, I will discuss two facets of nucleosome in eukaryotic gene control. On the one hand, nucleosome acts as a regulatory unit, which controls gene switches through a set of post-translational modifications occurring on histone tails. On the other hand, global configuration of nucleosome arrays with respect to nucleosome positioning, spacing and turnover acts as a tuning parameter for all genomic functions. A “histone code” hypothesis extents the Jacob-Monod model for eukaryotic gene control; however, when considering factors capable of reconfiguring entire nucleosome array, such as ATP-dependent chromatin remodelers, this model becomes limited. Global changes in nucleosome arrays will be sensed by every gene, yet the transcriptional responses might be specific and appear as gene targeted events. What determines such specificity is unclear, but it’s likely to depend on initial gene settings, such as availability of transcription factors, and on configuration of new nucleosome array state.
- DNA,
- nucleosome,
- chromatin,
- nucleosome positioning,
- histone code,
- gene control
Citation: Yuri M. Moshkin. Chromatin—a global buffer for eukaryotic gene control[J]. AIMS Biophysics, 2015, 2(4): 531-554. doi: 10.3934/biophy.2015.4.531

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Abstract

Most of eukaryotic DNA is embedded into nucleosome arrays formed by DNA wrapped around a core histone octamer. Nucleosome is a fundamental repeating unit of chromatin guarding access to the genetic information. Here, I will discuss two facets of nucleosome in eukaryotic gene control. On the one hand, nucleosome acts as a regulatory unit, which controls gene switches through a set of post-translational modifications occurring on histone tails. On the other hand, global configuration of nucleosome arrays with respect to nucleosome positioning, spacing and turnover acts as a tuning parameter for all genomic functions. A “histone code” hypothesis extents the Jacob-Monod model for eukaryotic gene control; however, when considering factors capable of reconfiguring entire nucleosome array, such as ATP-dependent chromatin remodelers, this model becomes limited. Global changes in nucleosome arrays will be sensed by every gene, yet the transcriptional responses might be specific and appear as gene targeted events. What determines such specificity is unclear, but it’s likely to depend on initial gene settings, such as availability of transcription factors, and on configuration of new nucleosome array state.

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