PDF(Pubmed)
Abstract：
Histone variants leading to altered nucleosome structure, dynamics and DNA accessibility occur frequently, albeit rarely for H4. We carried out a comprehensive in silico scrutiny of fungal genomes, which revealed the presence of a novel H4 variant (H4E) in the ascomycetes, throughout the Pezizomycotina, in basal species of the Taphrinomycotina and also in the Glomeromycota. The coding cognate genes show a specific intron/exon organization, different from H4 canonical genes. H4Es diverge from canonical H4s mainly in the N- and C-terminal extensions, showing marked differences in the distribution and number of Lys and Arg residues, which may result in novel post-translational modifications. In Aspergillus nidulans (Pezizomycotina, Eurotiomycetes) the H4E variant protein level is low in mycelia. However, the encoding gene is well expressed at 37°C under nitrogen starvation. H4E localizes to the nucleus and interacts with H3, but its absence or overexpression does not result in any detectable phenotype. Deletion of only one of the of the two canonical H4 genes results in a strikingly impaired growth phenotype, which indicates that H4E cannot replace this canonical histone. Thus, an H4 variant is present throughout a whole subphylum of the ascomycetes, but with hitherto no experimentally detectable function.
摘要：
组蛋白变异导致核小体结构改变,动态和DNA可及性经常发生，虽然很少为H4。我们对真菌基因组进行了全面的计算机审查，这揭示了子囊菌中存在一种新的H4变体（H4E），整个Pezizomycotina，在Taphrinomcotina和Glomomcota的基础物种中。编码同源基因显示特定的内含子/外显子组织，不同于H4规范基因。H4E主要在N端和C端延伸与规范的H4s不同，Lys和Arg残基的分布和数量显示出明显的差异，这可能导致新的翻译后修饰。在构巢曲霉（Pezizomycotina，Eurotimocetes）菌丝体中的H4E变异蛋白水平较低。然而,编码基因在37°C氮饥饿下良好表达。H4E定位于细胞核并与H3相互作用,但其不存在或过表达不会导致任何可检测的表型。仅缺失两个经典H4基因中的一个会导致明显受损的生长表型，这表明H4E不能取代这种典型的组蛋白。因此，H4变体存在于子囊菌的整个亚门中，但是迄今为止还没有实验上可检测的功能。
