Structural basis of substrate processing in modular polyketide synthases

模块化聚酮合酶底物加工的结构基础

• 批准号: 9247925
• 负责人: Georgios Skiniotis
• 金额: $ 7.28万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9247925
• 关键词: Active Sites; Acyl Carrier Protein; Antifungal Agents; Antiviral Agents; Architecture; Biochemical; Biological Assay; Biological Products; Biomedical Engineering; Catalysis; Complement; Cryoelectron Microscopy; Dimerization; Docking; Enzymes; Imagery; Immunosuppressive Agents; Individual; Length; Light; Link; Maps; Modeling; Molecular Conformation; Mutagenesis; Natural Products; Pathway interactions; Pharmacologic Substance; Positioning Attribute; Process; Proteins; Resolution; Sampling; Specific qualifier value; Structural Models; Structure; Substrate Interaction; System; Technology; Tertiary Protein Structure; Time; Type I Polyketide Synthase; Work; analog; antimicrobial; chemical synthesis; conformational conversion; conformer; design; dimer; drug discovery; enzyme substrate; experimental study; image processing; molecular dynamics; novel; picromycin; polyketide synthase; prototype; public health relevance; reconstruction; success

 DESCRIPTION (provided by applicant): Bacterial type I polyketide synthases (PKSs) are mega-enzyme assembly lines responsible for generating the macrolactone core of a wide range of polyketide products that are biologically active natural compounds (e.g. antimicrobial, antifungal, antiviral, anticancer, and immunosuppressant compounds). Indicative of their significance, polyketide natural products currently form the basis for nearly one-third of pharmaceuticals. PKSs employ a modular multi-step mechanism to produce polyketides, and bioengineering these systems has immense potential for the creation of new chemotypes with invaluable applications in drug discovery. However, such efforts have met with limited success, reflecting our poor structural and mechanistic understanding of the modular process to generate polyketides. We recently employed cryo-electron microscopy (cryo-EM) to show the first subnanometer resolution structures of the full length PikAIII module from the pikromycin PKS biosynthetic pathway, a prototype for assembly-line PKS systems. The findings not only revealed an unexpected module architecture undergoing extensive structural rearrangements, but also showed that the type of substrate linked to a highly mobile acyl carrier protein (ACP) domain specifies its positioning in a way that facilitates assembly-line throughput. By employing recent breakthroughs in cryo-EM technologies, we now aim to obtain high resolution cryo-EM structures of PikAIII and of the terminal PikAIV module, in an effort to resolve several lingering question regarding functional interfaces and module dynamics. Our studies will include both natural and unnatural substrates, seeking to reveal the principles of substrate recognition and processing in these remarkable macromolecular factories. The findings from the proposed studies will for the basis for renewed bioengineering efforts towards the creation of PKSs that can efficiently produce novel compounds of high medicinal value.