Cogan Dillon P, Soohoo Alexander M, Chen Muyuan, Liu Yan, Brodsky Krystal L, Khosla Chaitan
Department of Chemistry, Stanford University, Stanford, CA, USA.
Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, USA.
Nat Chem Biol. 2025 Jun;21(6):876-882. doi: 10.1038/s41589-024-01709-y. Epub 2024 Aug 23.
Assembly-line polyketide synthases (PKSs) are modular multi-enzyme systems with considerable potential for genetic reprogramming. Understanding how they selectively transport biosynthetic intermediates along a defined sequence of active sites could be harnessed to rationally alter PKS product structures. To investigate functional interactions between PKS catalytic and substrate acyl carrier protein (ACP) domains, we employed a bifunctional reagent to crosslink transient domain-domain interfaces of a prototypical assembly line, the 6-deoxyerythronolide B synthase, and resolved their structures by single-particle cryogenic electron microscopy (cryo-EM). Together with statistical per-particle image analysis of cryo-EM data, we uncovered interactions between ketosynthase (KS) and ACP domains that discriminate between intra-modular and inter-modular communication while reinforcing the relevance of conformational asymmetry during the catalytic cycle. Our findings provide a foundation for the structure-based design of hybrid PKSs comprising biosynthetic modules from different naturally occurring assembly lines.
流水线型聚酮合酶（PKSs）是模块化多酶系统，具有巨大的基因重编程潜力。了解它们如何沿着定义好的活性位点序列选择性地转运生物合成中间体，有助于合理改变PKS产物结构。为了研究PKS催化结构域与底物酰基载体蛋白（ACP）结构域之间的功能相互作用，我们使用双功能试剂交联典型流水线型6-脱氧红霉内酯B合酶的瞬时结构域-结构域界面，并通过单颗粒低温电子显微镜（cryo-EM）解析其结构。结合cryo-EM数据的统计单颗粒图像分析，我们发现了酮合成酶（KS）与ACP结构域之间的相互作用，这种相互作用区分了模块内和模块间的通讯，同时强化了催化循环中构象不对称的相关性。我们的研究结果为基于结构设计包含来自不同天然流水线型生物合成模块的杂合PKSs奠定了基础。
