Histone variation and chromatin stability. A few selected examples

Histone variation and chromatin stability. A few selected examples 

In the sections that follow, we are going to describe a few representative examples of how histone variability (histone variants and their post-translational modifications) can affect nucleosome stability and folding. This data supports the notion that while some of this variability may be exclusively used to provide an informational code [121,123,165] it can also have important implications for structural aspects involved in the highly dynamic nature of the chromatin fiber. 

The biological relevance of this histone variant has already been discussed in Section 2.2. As it was pointed out there, the recent crystallographic structure [41] of a nucleosome containing recombinant H2A.Z (rH2A.Z) revealed structural features that pointed towards a nucleosome destabilizing role for this histone variant (see Fig. 9A-B). Two recent papers [42,375] have pursued the preliminary findings established by this paper and proceeded with the structural characterization of chromatin complexes in solution. 

In contrast, the results of Fan et al. [375] using 208-12 nucleosome arrays that had been reconstituted with a full set of recombinant histones showed that rH2A.Z enhanced the intramolecular folding of these complexes while simultaneously inhibiting the formation of higher folding structures that result from intermolecular 

Histone acetylation is without a doubt one of the most thoroughly characterized post-translational modifications of histones where both the functional (see Section 3.1) and structural implications for chromatin have been explored. In the sections that follow we are going to summarize the major structural effects of this post-translational modification as they pertain to the nucleosome and the chromatin fiber. 

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