Department of Biochemistry & Microbiology, University of Victoria, Victoria, BC V8W 3P6, Canada.
Univ. Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33076, Pessac, France.
Sci Rep. 2017 Jun 19;7(1):3795. doi: 10.1038/s41598-017-04194-7.
The nucleoplasmin family of histone chaperones is identified by a pentamer-forming domain and multiple acidic tracts that mediate histone binding and chaperone activity. Within this family, a novel domain organization was recently discovered that consists of an N-terminal nucleoplasmin-like (NPL) domain and a C-terminal FKBP peptidyl-proline isomerase domain. Saccharomyces cerevisiae Fpr4 is one such protein. Here we report that in addition to its known histone prolyl isomerase activities, the Fpr4 FKBP domain binds to nucleosomes and nucleosome arrays in vitro. This ability is mediated by a collection of basic patches that enable the enzyme to stably associate with linker DNA. The interaction of the Fpr4 FKBP with recombinant chromatin complexes condenses nucleosome arrays independently of its catalytic activity. Based on phylogenetic comparisons we propose that the chromatin binding ability of 'basic' FKBPs is shared amongst related orthologues present in fungi, plants, and insects. Thus, a subclass of FKBP prolyl isomerase enzymes is recruited to linker regions of chromatin.
核质素家族的组蛋白伴侣通过五聚体形成结构域和多个介导组蛋白结合和伴侣活性的酸性结构域来识别。在这个家族中，最近发现了一种新的结构域组织，由 N 端核质素样（NPL）结构域和 C 端 FKBP 肽脯氨酰异构酶结构域组成。酿酒酵母 Fpr4 就是这样一种蛋白质。在这里，我们报告说，除了其已知的组蛋白脯氨酰异构酶活性外，Fpr4 FKBP 结构域还可以在体外与核小体和核小体阵列结合。这种能力是由一系列碱性斑块介导的，使酶能够与连接 DNA 稳定结合。Fpr4 FKBP 与重组染色质复合物的相互作用独立于其催化活性而使核小体阵列浓缩。基于系统发育比较，我们提出“碱性”FKBP 与真菌、植物和昆虫中存在的相关同源物具有共同的染色质结合能力。因此，一类 FKBP 脯氨酰异构酶酶被招募到染色质的连接区。
