It is currently proposed that histone modifications play vital roles in many fundamental biological processes by rearranging the structure and composition of chromatin. Mass spectrometry (MS) allows us not only to deduce the amino acid sequence of a peptide, but also to identify the exact sites and type of modifications in the peptide via the modified peptide mass shifts.Įpigenetic studies of chromatin in model organisms have provided insights into the modifications of histones, ranging from the identification of several enzymes and related effectors associated with histone modifications to their biological functions in cell development. Using techniques such as Western blotting and mass spectrometry, increasing number of histone modification sites have been identified in mouse, yeast, Drosophila melanogaster, Tetrahymena thermophila and A. Most of these modifications are dynamic and can be reversed by other enzymes, such as histone demethylase and HDAC (histone deacetylase). These modifications include methylation, acetylation, phosphorylation, ubiquitination, glycosylation, ADP ribosylation, carbonylation, sumoylation and biotinylation. In general, the N terminus of histone H3 and H4, and N and C terminus of H2A and H2B are prone to being covalently modified by many enzymes, such as HMT (histone methyltransferase) and HAT (histone acetyltransferase). An additional histone, H1 links these nucleosomes together along the chromatin chain. The fundamental structural unit of chromatin in eukaryotic cells is the nucleosome, that consists of 146 base pairs (bp) of DNA wrapped around a histone octamer, each of which is formed by two copies of H2A, H2B, H3 and H4. Histone modifications and histone variants play critical roles in regulating gene expression, modulating the cell cycle, and are responsible for maintaining genome stability. thaliana, thus providing important biological information toward further understanding of the histone modifications and their functional significance in higher plants. This work revealed several distinct variants of soybean histone and their modifications that were different from A. In the histone variant H4.1 and H4.2, the amino acid 60 was isoleucine and valine, respectively. In addition, two variants of histone H4 (H4.1 and H4.2) were also detected, which were missing in other organisms. Lysine 4 and Lysine 36 methylation were only detected in HISTONE H3.2, suggesting that HISTONE variant H3.2 might be associated with actively transcribing genes. The methylation patterns in these two HISTONE H3 variants also exhibited differences. They were different at positions of A 31F 41S 87S 90 (HISTONE variant H3.1) and T 31Y 41H 87L 90 (HISTONE variant H3.2), respectively. Using a combination of mass spectrometry and nano-liquid chromatography, two variants of HISTONE H3 were detected and their modifications were determined. Besides, acetylation at Lysine 8 and 12 of HISTONE H4 in soybean were identified. thaliana, mono- and di-methylated HISTONE H3 Lysine 79 were detected in soybean. Although methylation at HISTONE H3 Lysine 79 was not reported in A. We also observed that Lysine 27 methylation and Lysine 36 methylation usually excluded each other in HISTONE H3. Lysine 27 was prone to being mono-methylated, while tri-methylation was predominant at Lysine 36. In soybean leaves, mono-, di- and tri-methylation at Lysine 4, Lysine 27 and Lysine 36, and acetylation at Lysine 14, 18 and 23 were detected in HISTONE H3. To understand the biological functions of the global dynamics of histone modifications and histone variants in higher plants, we elucidated the variants and post-translational modifications of histones in soybean, a legume plant with a much bigger genome than that of Arabidopsis thaliana. Histone modifications and histone variants are of importance in many biological processes.
0 kommentar(er)
