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Structural visualization of transient interactions between the cis-acting acyltransferase and acyl carrier protein of the salinomycin modular polyketide synthase
Acta Crystallographica Section D ( IF 2.2 ) Pub Date : 2022-06-01 , DOI: 10.1107/s2059798322004612
Y Feng 1 , F Zhang 1 , S Huang 1 , Z Deng 1 , L Bai 1 , J Zheng 1
Affiliation  

Transient protein–protein interactions between cis-acting acyltransferase (AT) and acyl carrier protein (ACP) domains are critical for the catalysis and processivity of modular polyketide synthases (mPKSs), but are challenging for structural characterization due to the intrinsically weak binding affinity. Here, a stable complex of cis-acting AT and ACP domains from the ninth module of the salinomycin mPKS was obtained using a maleimide cross-linker and the structure of the complex was determined at 2.6 Å resolution. The crystal structure shows that the AT in combination with the ketosynthase (KS)-to-AT linker forms a C-shaped architecture to embrace the ACP. The large hydrolase subdomain of the AT serves as a major binding platform for the ACP, while the small ferredoxin-like subdomain of the AT and the KS-to-AT linker cooperate with each other to constrain binding of the ACP. The importance of interface residues in cis-acting AT–ACP interactions was confirmed by mutagenesis assays. The interaction mode observed in the cis-acting AT–ACP complex is completely different from those observed in trans-acting AT–ACP complexes, where the ACP primarily contacts the small domain of the AT. The complex structure provides detailed mechanistic insights into AT–ACP recognition in cis-AT mPKSs.

中文翻译:

盐霉素模块化聚酮合酶顺式酰基转移酶与酰基载体蛋白瞬时相互作用的结构可视化

顺式作用酰基转移酶 (AT) 和酰基载体蛋白 (ACP) 结构域之间的瞬时蛋白质-蛋白质相互作用对于模块化聚酮化合物合酶 (mPKS) 的催化和持续合成能力至关重要,但由于其固有的弱结合亲和力,因此对结构表征具有挑战性。在这里,一个稳定的顺式复合物使用马来酰亚胺交联剂获得盐霉素 mPKS 第九模块的作用 AT 和 ACP 结构域,并以 2.6 Å 分辨率确定复合物的结构。晶体结构表明,AT 与酮合酶 (KS)-to-AT 接头结合形成了一个 C 形结构以包含 ACP。AT 的大水解酶亚结构域作为 ACP 的主要结合平台,而 AT 的小类铁氧还蛋白亚结构域和 KS-to-AT 接头相互配合以限制 ACP 的结合。通过诱变试验证实了界面残基在顺式作用 AT-ACP 相互作用中的重要性。在顺式作用的 AT-ACP 复合物中观察到的相互作用模式与在反式中观察到的完全不同- 作用 AT-ACP 复合物,其中 ACP 主要接触 AT 的小区域。复杂的结构为cis -AT mPKSs中的 AT-ACP 识别提供了详细的机制见解。
更新日期:2022-06-03
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