染色质是真核生物遗传物质的包装形式。按照其包装的致密程度，染色质可分为较为松散的常染色质和较为致密的异染色质。异染色质的这种结构特征不利于蛋白质的招募，因而可能会危及到正常的异染色质DNA代谢过程，例如DNA复制和重组。
1月13日，PLoS Genetics杂志发表了上海生科院生化与细胞所周金秋研究组关于酿酒酵母异染色质组蛋白标记的文章。他们发现组蛋白乙酰化酶复合物NuA4能够被招募到端粒异染色质区，并特异性地乙酰化组蛋白H4第12位赖氨酸。该位点的乙酰化对端粒异染色质的基本DNA代谢过程起调控作用。这一研究表明，异染色质并不像人们以往认为的那样“静默”，它同样具备可塑性，而这种异染色质的可塑性直接归因于它自身的化学性质。
该论文是由周金秋研究组的助理研究员周波和博士研究生王珊珊等完成。该课题获得了国家科技部和国家自然科学基金委的经费资助。（生物谷Bioon.com）
生物谷推荐原文出处：
PLoS Genet 7(1): e1001272. doi:10.1371/journal.pgen.1001272
Histone H4 Lysine 12 Acetylation Regulates Telomeric Heterochromatin Plasticity in Saccharomyces cerevisiae
Bo O. Zhou1, Shan-Shan Wang1, Yang Zhang1, Xiao-Hong Fu1, Wei Dang1, Brian A. Lenzmeier2, Jin-Qiu Zhou1*
1 State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China, 2 School of Science, Buena Vista University, Storm Lake, Iowa, United States of America
Abstract
Recent studies have established that the highly condensed and transcriptionally silent heterochromatic domains in budding yeast are virtually dynamic structures. The underlying mechanisms for heterochromatin dynamics, however, remain obscure. In this study, we show that histones are dynamically acetylated on H4K12 at telomeric heterochromatin, and this acetylation regulates several of the dynamic telomere properties. Using a de novo heterochromatin formation assay, we surprisingly found that acetylated H4K12 survived the formation of telomeric heterochromatin. Consistently, the histone acetyltransferase complex NuA4 bound to silenced telomeric regions and acetylated H4K12. H4K12 acetylation prevented the over-accumulation of Sir proteins at telomeric heterochromatin and elimination of this acetylation caused defects in multiple telomere-related processes, including transcription, telomere replication, and recombination. Together, these data shed light on a potential histone acetylation mark within telomeric heterochromatin that contributes to telomere plasticity.
