title: Enzyme-Dependent [4 + 2] Cycloaddition Depends on Lid-like Interaction of the N-Terminal Sequence with the Catalytic Core in PyrI4.
abstract: The Diels-Alder [4 + 2] cycloaddition reaction is one of the most powerful and elegant organic synthesis methods for forming 6-membered molecules and has been known for nearly a century. However, whether and how enzymes catalyze this type of reaction is still not completely clear. Here we focus on PyrI4, an enzyme found in the biosynthetic pathway of pyrroindomycins where it catalyzes the formation of a spiro-conjugate via an enzyme-dependent exo-selective [4 + 2] cycloaddition reaction. We report the crystal structures of PyrI4 alone and in complex with its product. Comparative analysis of these structures, combined with biochemical analysis, lead us to propose a unique trapping mechanism whereby the lid-like action of the N-terminal tail imposes conformational constraints on the β barrel catalytic core, which enhances the proximity and polarization effects of reactive groups (1,3-diene and alkene) to drive cyclization in a regio- and stereo-specific manner. This work represents an important step toward the wider application of enzyme-catalyzed [4 + 2] cyclization for synthetic purposes.
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Qingfei
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Zhixiong
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Zhuhua
authors.initials: Z
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China; Huzhou Center of Bio-Synthetic Innovation, 1366 Hongfeng Road, Huzhou 313000, China.
authors.forename: Jiequn
authors.initials: J
authors.lastname: Wu
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203, China.
authors.forename: Huaiyu
authors.initials: H
authors.lastname: Yang
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu-Chong-Zhi Road, Shanghai 201203, China.
authors.forename: Hualiang
authors.initials: H
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China. Electronic address: panlf@sioc.ac.cn.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China; Huzhou Center of Bio-Synthetic Innovation, 1366 Hongfeng Road, Huzhou 313000, China. Electronic address: wliu@mail.sioc.ac.cn.
authors.forename: Wen
authors.initials: W
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D055162:Biocatalysis; D061565:Cycloaddition Reaction; D018942:Macrolides / Q000737:chemistry / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010453:Peptide Synthases / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D013141:Spiro Compounds / Q000737:chemistry / Q000378:metabolism
chemical_list: D018942:Macrolides; D013141:Spiro Compounds; D010453:Peptide Synthases