Functional Assignment among Chromatin Chaperones

本研究的目的是系统地鉴定参与染色质重塑的染色质伴侣，阐明其活性的调控机制以及它们之间的功能分配。我们以腺病毒DNA与病毒碱性核心蛋白复合物为模板，通过重组和解剖无细胞复制和转录系统，除了先前鉴定的TAF-Ⅰ和TAF-Ⅱ/核小体组装蛋白-Ⅰ外，还鉴定了模板激活因子（TAF）-Ⅲ。TAF-III显示与核磷蛋白/B23相同。对突变蛋白的分析表明，三种蛋白中的高酸性氨基区域对其染色质重塑活性是必不可少的。我们建议这些蛋白质的术语“酸性分子伴侣”。每种TAF-I或TAF-III由两种亚型组成，其中一种的活性比另一种低得多。我们发现了细胞中这两种亚型的比例与活性水平有关的可能性。染色质 ...更多信息 在有丝分裂期，TAF-I和TAF-III的重塑活性被磷酸化并显著降低。我们发现，磷酸化的有丝分裂特异性蛋白激酶，包括细胞周期蛋白B/cdc 2负调控他们的染色质重塑活性。结果表明，TAF-Ⅰ和TAF-Ⅲ分别存在于细胞核和核仁中，TAF-Ⅱ是一种核质穿梭蛋白。TAF-I不仅参与腺病毒染色质，而且参与用纯化的组蛋白和质粒DNA重建的细胞型染色质。使用酵母细胞的遗传实验表明，穿梭，而不是核定位是重要的有丝分裂的进展。染色质免疫沉淀分析表明TAF-III与核糖体DNA区域相关。通过对流感病毒核糖核蛋白的功能分析，我们鉴定出RAF（RNA聚合酶激活因子）-1和RAF-2 p48/NPI 5/BAT-1/UAP 56为酸性分子伴侣家族成员。因此，这表明，归类到这个家庭的蛋白质不仅参与DNA-蛋白质复合物的功能调节，而且RNA-蛋白质复合物。少

The aim of this study is to systematically identify chromatin chaperones involved in chromatin remodeling and to clarify the regulatory mechanism of their activities and the functional assignment among them. We have identified Template Activating Facor (TAF)-III in addition to previously identified TAF-I and TAF-II/Nucleosome Assembly Protein-I by reconstitution and dissection of cell free replication and transcription systems with the adenovirus DNA complexed with viral basic core proteins astemplate. TAF-III was shown identical with nucleophosmin/B23. Analyzes with mutated proteins revealed that the highly acidic amino region in three proteins is essential for their chromatin remodeling activity. We proposed the term "acidic molecular chaperone" for these proteins. Each TAF-I or TAF-III consists of two subtypes, one of which has much less activity than the other. We showed the possibility that the ratio of these two subtypes in a cell is involved in the activity level. The chromatin … More remodeling activity of TAF-I and TAF-III was phosphorylated and markedly reduced : during the mitotic phase. We showed that phosphorylation by a mitotic-specific protein kinase including cyclin B/cdc2 negatively regulates their chromatin remodeling activity. It was indicated that TAF-I and TAF-III exist in nucleus and nucleolus, respectively, while TAF-II was found a nucleocytoplasmic shuttling protein. TAF-I was involved in not only the adenovirus chromatin but also the cellular type chromatin reconstituted with purified histones and plasmid DNA. Genetic experiments using yeast cells indicated that Shuttling but not nuclear localization is important for mitotic progression. Chromatin immunoprecipitation assays showed that TAF-III is associated with the ribosome DNA region. Of interest, is that by functuional analysis of influenza virus ribonucleoproteins, we identified RAF (RNA polymerase Activating Factor)-1 and RAF-2p48/NPI 5/BAT-1/UAP56 as a family member of the acidic molecular chaperone. Thus, it is suggested that proteins categorized into this family involves in function regulation of not only DNA-protein complexes but also RNA-protein complexes. Less