title: The unusual macrocycle forming thioesterase of mycolactone.
abstract: Mycolactone is a polyketide natural product secreted by Mycobacterium ulcerans, the organism responsible for the tropical skin disease Buruli ulcer. The finding that this small molecule virulence factor is sufficient to reconstitute the necrotic pathology associated with Buruli ulcer suggests that a better understanding of mycolactone biosynthesis, particularly the processes which are distinct from those in human metabolism, may provide a unique avenue for the development of selective therapeutics. In the present study we have cloned, expressed, and biochemically characterized the putative macrocycle forming thioesterase for mycolactone, MLSA2 TE. We have evaluated the enzyme both as the truncated thioesterase domain and as a carrier protein-linked didomain construct. The results of these analyses distinguish MLSA2 TE from traditional fatty acid and polyketide synthase TE-domains in terms of its sequence, kinetic parameters, and susceptibility to traditional active-site directed inhibitors. These findings suggest that MLSA2 TE utilizes a unique biochemical mechanism for macrocycle formation.
authors.affiliation: Department of Chemistry and Biochemistry, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, USA.
authors.forename: Jordan L
authors.initials: JL
authors.lastname: Meier
authors.forename: Tiffany
authors.initials: T
authors.lastname: Barrows-Yano
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Foley
authors.forename: Candice L
authors.initials: CL
authors.lastname: Wike
authors.forename: Michael D
authors.initials: MD
authors.lastname: Burkart
mesh_terms: D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D020134:Catalytic Domain; D003001:Cloning, Molecular; D003500:Cyclization; D020869:Gene Expression Profiling; D006868:Hydrolysis; D007700:Kinetics; D047028:Macrocyclic Compounds / Q000737:chemistry / Q000378:metabolism*; D018942:Macrolides; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017421:Sequence Analysis; D013869:Thiolester Hydrolases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; D047028:Macrocyclic Compounds; D018942:Macrolides; D011994:Recombinant Proteins; C117218:mycolactone; D013869:Thiolester Hydrolases