Open AccessWhat determines the folding of the chromatin fiber?
Author(s) -
Kensal van Holde,
Jordanka Zlatanova
Publication year - 1996
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.93.20.10548
Subject(s) - nucleosome , histone , linker dna , chromatin , linker , histone code , acetylation , biophysics , histone h1 , microbiology and biotechnology , biology , chemistry , dna , computational biology , genetics , computer science , gene , operating system
In this review, we attempt to summarize, in a critical manner, what is currently known about the processes of condensation and decondensation of chromatin fibers. We begin with a critical analysis of the possible mechanisms for condensation, considering both old and new evidence as to whether the linker DNA between nucleosomes bends or remains straight in the condensed structure. Concluding that the preponderance of evidence is for straight linkers, we ask what other fundamental process might allow condensation, and argue that there is evidence for linker histone-induced contraction of the internucleosome angle, as salt concentration is raised toward physiological levels. We also ask how certain specific regions of chromatin can become decondensed, even at physiological salt concentration, to allow transcription. We consider linker histone depletion and acetylation of the core histone tails, as possible mechanisms. On the basis of recent evidence, we suggest a unified model linking targeted acetylation of specific genomic regions to linker histone depletion, with unfolding of the condensed fiber as a consequence.