Evolving contributions of the origin recognition complex (ORC) to subtelomeric chromatin

基因复制是分子进化的驱动力，因为它提供了新的遗传物质，可以在生物体中适应不同的目的。该项目旨在阐明重复基因如何分化及其编码蛋白如何获得不同的特性。特别地，该研究将检查最初能够发挥一种功能的蛋白质基序如何在细胞中适应执行其他功能。该项目还旨在将研究与培养本科生和研究生相结合，使他们获得设计、执行和解释实验的实践经验。此外，计划从事本科教育的博士后将在为期三周的冬季课程中，通过在实验室指导本科生，制定和实施本科生实验课程评估以及设计和教学课程来获得教学经验。最后，本项目将通过开发用于比较进化研究的额外酵母菌种来增加模式生物的遗传资源。复制基因的命运在理论上已经有了很好的模型。然而，很少有关于基因复制的研究超越了序列分析，以阐明当复制基因分化时蛋白质功能发生的变化。该项目将通过追踪起源识别复合体（ORC）亚基产生的两种蛋白质的进化来帮助填补这一知识空白。ORC促进DNA合成的预复制复合体的组装，其六个亚基中有五个含有结合和水解ATP的AAA+结构域。在出芽酵母谱系中，Orc1复制产生异染色质蛋白Sir3， Orc4产生端粒结合蛋白Rif2。Sir3和Rif2都缺乏atp酶活性，并重新利用AAA+结构域与其他蛋白质结合。本研究将比较Orc1/Sir3和Orc4/Rif2在非复制和复制酵母物种中的分子特性，重点研究它们的蛋白质相互作用和基因组分布。此外，这些蛋白质对转录抑制和端粒长度调节的贡献将被检查。这些发现将通过确定新的蛋白质功能如何以及何时出现来阐明和澄清基因复制的理论模型。

Gene duplication is a driving force in molecular evolution, as it provides new genetic material that can be adapted to serve different purposes in living organisms. This project is aimed at elucidating how duplicate genes diverge and their encoded proteins acquire distinct properties. In particular, the research will examine how a protein motif originally capable of one function can be adapted to perform other functions in the cell. The project is also designed to integrate research with training of undergraduate and graduate students who will gain hands-on experience in designing, executing, and interpreting experiments. In addition, a postdoctoral fellow who is planning a career in undergraduate education will gain teaching experience by coaching undergraduates in the laboratory, developing and implementing assessments for an undergraduate laboratory course, and designing and teaching a course during the three-week winter session. Finally, this project will enhance genetic resources for model organisms by developing additional yeast species for comparative evolutionary studies.The fates of duplicate genes are well-modeled theoretically. However, few studies of gene duplication move beyond sequence analysis to elucidate the changes that occur in protein function as duplicated genes diverge. The project will help fill this knowledge gap by tracing the evolution of two proteins that arose from subunits of the origin recognition complex (ORC). ORC promotes the assembly of a pre-replication complex for DNA synthesis, and five of its six subunits contain AAA+ domains that bind and hydrolyze ATP. In the budding yeast lineage, Orc1 duplicated to yield the heterochromatin protein Sir3, and Orc4 gave rise to the telomere-binding protein Rif2. Both Sir3 and Rif2 lack ATPase activity and have repurposed the AAA+ domain to bind other proteins. The research will compare the molecular properties of Orc1/Sir3 and Orc4/Rif2 in non-duplicated and duplicated yeast species, focusing on their protein interactions and genomic distributions. In addition, the contributions of these proteins to transcriptional repression and telomere length regulation will be examined. The findings will illustrate and clarify theoretical models of gene duplication by identifying how and when new protein functions arise.