Dumay-Odelot Hélène, Marck Christian, Durrieu-Gaillard Stéphanie, Lefebvre Olivier, Jourdain Sabine, Prochazkova Martina, Pflieger Aude, Teichmann Martin
Institut Européen de Chimie et Biologie (I.E.C.B.), Université Bordeaux 2 Victor Ségalen, INSERM U869, rue Robert Escarpit, Pessac, F-33607, France.
J Biol Chem. 2007 Jun 8;282(23):17179-89. doi: 10.1074/jbc.M611542200. Epub 2007 Apr 4.
TFIIIC in yeast and humans is required for transcription of tRNA and 5 S RNA genes by RNA polymerase III. In the yeast Saccharomyces cerevisiae, TFIIIC is composed of six subunits, five of which are conserved in humans. We report the identification, molecular cloning, and characterization of the sixth subunit of human TFIIIC, TFIIIC35, which is related to the smallest subunit of yeast TFIIIC. Human TFIIIC35 does not contain the phosphoglycerate mutase domain of its yeast counterpart, and these two proteins display only limited homology within a 34-amino acid domain. Homologs of the sixth TFIIIC subunit are also identified in other eukaryotes, and their phylogenic evolution is analyzed. Affinity-purified human TFIIIC from an epitope-tagged TFIIIC35 cell line is active in binding to and in transcription of the VA1 gene in vitro. Furthermore, TFIIIC35 specifically interacts with the human TFIIIC subunits TFIIIC63 and, to a lesser extent, TFIIIC90 in vitro. Finally, we determined a limited region in the smallest subunit of yeast TFIIIC that is sufficient for interacting with the yeast TFIIIC subunit ScTfc1 (orthologous to TFIIIC63) and found it to be adjacent to and overlap the 34-amino acid domain that is conserved from yeast to humans.
酵母和人类中的TFIIIC是RNA聚合酶III转录tRNA和5S RNA基因所必需的。在酿酒酵母中，TFIIIC由六个亚基组成，其中五个在人类中是保守的。我们报告了人类TFIIIC第六个亚基TFIIIC35的鉴定、分子克隆和特征，它与酵母TFIIIC的最小亚基相关。人类TFIIIC35不包含其酵母对应物的磷酸甘油酸变位酶结构域，并且这两种蛋白质在一个34个氨基酸的结构域内仅显示有限的同源性。在其他真核生物中也鉴定出了TFIIIC第六个亚基的同源物，并分析了它们的系统发育进化。从带有表位标签的TFIIIC35细胞系中亲和纯化的人类TFIIIC在体外与VA1基因结合并转录时具有活性。此外，TFIIIC35在体外与人TFIIIC亚基TFIIIC63以及在较小程度上与TFIIIC90特异性相互作用。最后，我们确定了酵母TFIIIC最小亚基中一个有限的区域，该区域足以与酵母TFIIIC亚基ScTfc1（与TFIIIC63直系同源）相互作用，并发现它与从酵母到人类保守的34个氨基酸结构域相邻且重叠。
