Collins Sean R, Miller Kyle M, Maas Nancy L, Roguev Assen, Fillingham Jeffrey, Chu Clement S, Schuldiner Maya, Gebbia Marinella, Recht Judith, Shales Michael, Ding Huiming, Xu Hong, Han Junhong, Ingvarsdottir Kristin, Cheng Benjamin, Andrews Brenda, Boone Charles, Berger Shelley L, Hieter Phil, Zhang Zhiguo, Brown Grant W, Ingles C James, Emili Andrew, Allis C David, Toczyski David P, Weissman Jonathan S, Greenblatt Jack F, Krogan Nevan J
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158, USA.
Nature. 2007 Apr 12;446(7137):806-10. doi: 10.1038/nature05649. Epub 2007 Feb 21.
Defining the functional relationships between proteins is critical for understanding virtually all aspects of cell biology. Large-scale identification of protein complexes has provided one important step towards this goal; however, even knowledge of the stoichiometry, affinity and lifetime of every protein-protein interaction would not reveal the functional relationships between and within such complexes. Genetic interactions can provide functional information that is largely invisible to protein-protein interaction data sets. Here we present an epistatic miniarray profile (E-MAP) consisting of quantitative pairwise measurements of the genetic interactions between 743 Saccharomyces cerevisiae genes involved in various aspects of chromosome biology (including DNA replication/repair, chromatid segregation and transcriptional regulation). This E-MAP reveals that physical interactions fall into two well-represented classes distinguished by whether or not the individual proteins act coherently to carry out a common function. Thus, genetic interaction data make it possible to dissect functionally multi-protein complexes, including Mediator, and to organize distinct protein complexes into pathways. In one pathway defined here, we show that Rtt109 is the founding member of a novel class of histone acetyltransferases responsible for Asf1-dependent acetylation of histone H3 on lysine 56. This modification, in turn, enables a ubiquitin ligase complex containing the cullin Rtt101 to ensure genomic integrity during DNA replication.
确定蛋白质之间的功能关系对于理解细胞生物学的几乎所有方面都至关重要。大规模鉴定蛋白质复合物为此目标迈出了重要的一步；然而，即便了解了每一个蛋白质-蛋白质相互作用的化学计量、亲和力和寿命，也无法揭示这些复合物之间以及内部的功能关系。遗传相互作用能够提供蛋白质-蛋白质相互作用数据集在很大程度上无法看到的功能信息。在此，我们展示了一种上位性微阵列图谱（E-MAP），它由对参与染色体生物学各个方面（包括DNA复制/修复、染色单体分离和转录调控）的743个酿酒酵母基因之间的遗传相互作用进行的定量成对测量组成。这一E-MAP揭示出，物理相互作用可分为两类，其显著特征是各个蛋白质是否协同发挥作用以执行共同功能。因此，遗传相互作用数据使得剖析包括中介体在内的功能多蛋白复合物以及将不同的蛋白质复合物组织成途径成为可能。在此定义的一条途径中，我们表明Rtt109是一类新型组蛋白乙酰转移酶的首个成员，这类酶负责依赖于Asf1的组蛋白H3赖氨酸56位的乙酰化。反过来，这种修饰使得一个含有cullin Rtt101的泛素连接酶复合物能够在DNA复制过程中确保基因组完整性。
