Abstract
Histones are the main structural components of the nucleosome, hence targets of many regulatory proteins that mediate processes involving changes in chromatin. The functional outcome of many pathways is “written” in the histones in the form of post-translational modifications that determine the final gene expression readout. As a result, modifications, alone or in combination, are important determinants of chromatin states. Histone modifications are accomplished by the addition of different chemical groups such as methyl, acetyl and phosphate. Thus, identifying and characterizing these modifications and the proteins related to them is the initial step to understanding the mechanisms of gene regulation and in the future may even provide tools for breeding programs. Several studies over the past years have contributed to increase our knowledge of epigenetic gene regulation in model organisms like Arabidopsis, yet this field remains relatively unexplored in crops. In this study we identified and initially characterized histones H3 and H4 in the monocot crop sugarcane. We discovered a number of histone genes by searching the sugarcane ESTs database. The proteins encoded correspond to canonical histones, and their variants. We also purified bulk histones and used them to map post-translational modifications in the histones H3 and H4 using mass spectrometry. Several modifications conserved in other plants, and also novel modified residues, were identified. In particular, we report O-acetylation of serine, threonine and tyrosine, a recently identified modification conserved in several eukaryotes. Additionally, the sub-nuclear localization of some well-studied modifications (i.e., H3K4me3, H3K9me2, H3K27me3, H3K9ac, H3T3ph) is described and compared to other plant species. To our knowledge, this is the first report of histones H3 and H4 as well as their post-translational modifications in sugarcane, and will provide a starting point for the study of chromatin regulation in this crop.
Highlights
The DNA of Eukaryotes is associated with proteins to form a highly dynamic complex called chromatin
Phylogenetic analysis between centromeric histone H3 (CENH3) from Saccharum sp. and proteins from other monocots indicates that the two isoforms present in sugarcane likely evolved after their divergence from sorghum
CENH3 isoforms from Luzula nivea and Hordeum vulgare are more similar to each other than to proteins from other species suggesting that CENH3 isoforms likely arose multiple times during monocot evolution (Figure B in S2 Fig)
Summary
The DNA of Eukaryotes is associated with proteins to form a highly dynamic complex called chromatin. The chromatin is composed of nucleosomes, which consist of an octamer of histone proteins. Nucleosomes are bound by the linker histone H1, to form the lowest level of chromatin condensation, the 10-nm fiber. In the level of compaction, the 10-nm fiber coils, originating the 30-nm fiber. The chromatin is present mostly in the form of 10-nm fiber, parts of 30-nm fiber and regions folded in looped domains (reviewed in [1]). Condensed chromatin domains are predominantly associated with transcriptionally inactive and gene poor sequences, and are referred to as heterochromatin. Euchromatin includes the less compacted domains associated with high transcriptional activity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
