Global analysis for functional residues of histone variant Htz1 using the comprehensive point mutant library
Global analysis for functional residues of histone variant Htz1 using the comprehensive point mutant library
复制标题
使用综合点突变文库对组蛋白变体 Htz1 的功能残基进行全局分析
DOI：
10.1111/j.1365-2443.2011.01512.x
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发表时间：
2011
期刊：
影响因子：
2.1
通讯作者：
M.Horikoshi & Y.Yamaguchi
中科院分区：
文献类型：
--
作者：
A.Kawano;Y.Hayashi;S.Noguchi;H.Handa;M.Horikoshi & Y.Yamaguchi
组蛋白变体执行独特的功能，并通过与典型组蛋白不同的机制沉积到DNA上。H2A变体，H2A.Z，在酿酒酵母中也称为Htz1，在基因组中分布不均匀，但有助于靶基因启动子的转录激活和异染色质基因座的抗沉默。Htz1还参与DNA复制、DNA修复、染色体分离和细胞周期控制。它与经典H2A的序列同一性仅为60%，并且可能是非保守残基负责Htz1特异性功能。然而，这些变体特异性残基的确切作用还不清楚。为了深入了解典型组蛋白和变体组蛋白之间功能差异的分子基础，本研究构建了117个Htz1丙氨酸扫描点突变体，并进行了化学遗传筛选。因此，鉴定了突变时赋予一种或多种异常表型的7个Htz1残基。基于H2A和Htz1之间的一级序列和功能保守性，其中两个残基（F32和I109）似乎具有Htz1特异性作用，而其余残基似乎具有H2A和Htz1之间共享的功能。本研究为今后研究典型组蛋白和变异组蛋白之间的功能趋同和趋异提供了有用的资源。
Histone variants perform unique functions and are deposited onto DNA by mechanisms distinct from those of canonical histones. The H2A variant, H2A.Z, also known as Htz1 inSaccharomyces cerevisiae, is not uniformly distributed across the genome but facilitates transcriptional activation at target gene promoters and anti‐silencing at heterochromatin loci. Htz1 is also involved in DNA replication, DNA repair, chromosome segregation and cell cycle control. Its sequence identity to canonical H2A is only ∼60%, and it is likely that the nonconserved residues are responsible for Htz1‐specific functions. However, precise roles of these variant‐specific residues are not well understood. To gain insights into the molecular basis underlying the functional differences between canonical and variant histones, 117 alanine‐scanning point mutants of Htz1 were constructed for this study, and chemical genetic screens were carried out. Consequently, seven Htz1 residues that conferred one or more abnormal phenotypes when mutated were identified. Based on primary sequence and functional conservation between H2A and Htz1, two of these residues (F32 and I109) appear to have an Htz1‐specific role, whereas the rest seem to have functions shared between H2A and Htz1. This study provides a useful resource for future investigations into functional convergence and divergence between canonical and variant histones.