DNA bending mediated by ORC is essential for replication licensing in budding yeast

• 成果类型: Article
• 署名作者: Lam, Wai Hei; Yu, Daqi; Zhang, Qiongdan; Lin, Yuhan; Li, Ningning; Li, Jian; Wu, Yue; Zhang, Yingyi; Gao, Ning; Tye, Bik Kwoon; Zhai, Yuanliang; Dang, Shangyu
• 署名单位: Hong Kong University of Science & Technology; University of Hong Kong; Peking University; Cornell University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11978
• DOI: 10.1073/pnas.2502277122
• 发表日期: 2025-04-08
• 关键词: cryo-em structure; cell-cycle; origin; complex; RECOGNITION; reveals; localization; facilitate; initiation; mechanism

摘要

In eukaryotes, the origin recognition complex (ORC) promotes the assembly of minichromosome maintenance 2 to 7 complexes into a head-to-head double hexamer at origin DNA in a process known as replication licensing. In this study, we present a series of cryoelectron microscopy structures of yeast ORC mutants in complex with origin DNA. We show that Orc6, the smallest subunit of ORC, utilizes its transcription factor II B-B domain to orchestrate the sequential binding of ORC to origin DNA. In addition, Orc6 plays the role of a scaffold by stabilizing the basic patch (BP) of Orc5 for ORC to capture and bend origin DNA. Importantly, disrupting DNA bending through mutating three key residues in Orc5-BP impairs ORC's ability to promote replication initiation at two points during the pre-RC assembly process. This study dissects the multifaceted role of Orc6 in orchestrating ORC's activities on DNA and underscores the vital role of DNA bending by ORC in replication licensing.