學術研究 • ACADEMIC RESEARCH 澳大新語 • 2023 UMAGAZINE 27 62 周昶行是澳大健康科學學院副教授，擁有牛津大學生物化學本科/碩士學位、倫敦癌症研究院哲學博士學位。他運 用結構生物學技術來研究基本的生物學過程，聚焦領域包括細胞分裂、染色質結構和表觀遺傳學。 William Chao is an associate professor in the Faculty of Health Sciences at UM. He holds a PhD from the Institute of Cancer Research in London, and an MBiochem from the University of Oxford. He applies structural biology techniques to study fundamental biological processes, particularly in the areas of cell division, chromatin structure, and epigenetics. 「學術研究」為投稿欄目，內容僅代表作者個人意見。 Articles in the Academic Research column were submitted by UM scholars. The views expressed are solely those of the author(s). The Self-Defense Mechanism of Vibrio Parahaemolyticus To prevent committing suicide, V. parahaemolyticus produces an immunity protein called RhsPI to protect itself against its toxin. This RhsPI immunity protein binds to RhsPC and forms an RhsPC-RhsPI toxin-immunity pair to neutralise the toxicity by interacting with the active site of the RhsPC nuclease. New Protein Structures Revealed With the support of one of the most advanced third-generation synchrotron light sources in the world, the Shanghai Synchrotron Light Source of the Chinese Academy of Sciences (CAS), we used X-ray crystallography to determine the atomic structure of the RhsPC-RhsPI toxin-immunity pair and gain a detailed understanding of how the RhsPI immunity protein protects against the toxicity of RhsPC. This discovery marks the first case where X-ray crystallography has been used to determine a new complex protein structure by researchers based in Macao. In addition, we collaborated with the team of Dr He Jun, a researcher at the Guangzhou Institute of Biomedicine and Health of the CAS, to use advanced cryo-electron microscopy techniques to reveal the structural changes and dimerisation of RhsP caused by autoproteolysis. This is also the first time that a Macao-based research institute has used cryo-electron microscopy to determine a new protein structure. These findings were published in the journal Cell Reports. A Path to Unravel RhsP Toxin Delivery Mechanism While our results have shown that RhsP dimerisation is a crucial step for V. parahaemolyticus to target its neighbours, the reason for this is still unclear. Further studies are needed to determine whether dimerisation occurs before RhsP is delivered via the T6SS or after the toxin has reached its target. RhsP毒素的自體蛋白分解促進其二聚化。這是RhsP發揮毒性，使腸炎弧菌得以攻擊鄰菌的必要一步。 Autoproteolysis of RhsP toxin can promote its dimerisation, which is a necessary step for prey targeting
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