title: Structural and functional analysis of two di-domain aromatase/cyclases from type II polyketide synthases.
abstract: Aromatic polyketides make up a large class of natural products with diverse bioactivity. During biosynthesis, linear poly-β-ketone intermediates are regiospecifically cyclized, yielding molecules with defined cyclization patterns that are crucial for polyketide bioactivity. The aromatase/cyclases (ARO/CYCs) are responsible for regiospecific cyclization of bacterial polyketides. The two most common cyclization patterns are C7-C12 and C9-C14 cyclizations. We have previously characterized three monodomain ARO/CYCs: ZhuI, TcmN, and WhiE. The last remaining uncharacterized class of ARO/CYCs is the di-domain ARO/CYCs, which catalyze C7-C12 cyclization and/or aromatization. Di-domain ARO/CYCs can further be separated into two subclasses: "nonreducing" ARO/CYCs, which act on nonreduced poly-β-ketones, and "reducing" ARO/CYCs, which act on cyclized C9 reduced poly-β-ketones. For years, the functional role of each domain in cyclization and aromatization for di-domain ARO/CYCs has remained a mystery. Here we present what is to our knowledge the first structural and functional analysis, along with an in-depth comparison, of the nonreducing (StfQ) and reducing (BexL) di-domain ARO/CYCs. This work completes the structural and functional characterization of mono- and di-domain ARO/CYCs in bacterial type II polyketide synthases and lays the groundwork for engineered biosynthesis of new bioactive polyketides.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Grace
authors.initials: G
authors.lastname: Caldara-Festin
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697; drjackso@uci.edu sctsai@uci.edu.
authors.forename: David R
authors.initials: DR
authors.lastname: Jackson
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Jesus F
authors.initials: JF
authors.lastname: Barajas
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Valentic
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Avinash B
authors.initials: AB
authors.lastname: Patel
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Stephanie
authors.initials: S
authors.lastname: Aguilar
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: MyChi
authors.initials: M
authors.lastname: Nguyen
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Michael
authors.initials: M
authors.lastname: Vo
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697;
authors.forename: Avinash
authors.initials: A
authors.lastname: Khanna
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, TX 78712; Department of Chemistry, University of Texas, Austin, TX 78712.
authors.forename: Eita
authors.initials: E
authors.lastname: Sasaki
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, TX 78712; Department of Chemistry, University of Texas, Austin, TX 78712.
authors.forename: Hung-Wen
authors.initials: HW
authors.lastname: Liu
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697; Department of Chemistry, University of California, Irvine, CA 92697; Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697; drjackso@uci.edu sctsai@uci.edu.
authors.forename: Shiou-Chuan
authors.initials: SC
authors.lastname: Tsai
mesh_terms: D001141:Aromatase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D016296:Mutagenesis; D048630:Polyketide Synthases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D048630:Polyketide Synthases; D001141:Aromatase
keywords: aromatase/cyclase; polyketide biosynthesis; structural biology