title: Biosynthetic Studies of omega-Cycloheptyl Fatty Acids in Alicyclobacillus cycloheptanicus. Formation of Cycloheptanecarboxylic Acid from Phenylacetic Acid.
abstract: The formation of the structurally novel, mono-substituted cycloheptane ring in omega-cycloheptyl fatty acids in Alicyclobacillus cycloheptanicus (formerly Bacillus cycloheptanicus) has been examined. Feeding experiments with (13)C- and (2)H-labeled intermediates demonstrated that cycloheptanecarboxylic acid (3), probably as its CoA thioester, is the starter unit for omega-cycloheptyl fatty acid biosynthesis. Analysis of the resultant labeling pattern from a feeding experiment with [U-(13)C(6)]glucose suggested a shikimate pathway origin of 3 via aromatic amino acids. [1,2-(13)C(2)]Phenylacetic acid (6) was efficiently metabolized into the 3-derived moiety in a manner reminiscent of the seven-membered ring Pseudomonas metabolite thiotropocin. The fates of the aromatic and benzylic hydrogens of 6 were determined; these dictated various boundary conditions for the biosynthetic pathway from 6 to 3. Taken together with the results from feeding experiments with postulated cycloheptenylcarboxylate biosynthetic intermediates, the data lead us to propose a pathway which involves an oxidative ring-expansion of 6 to a hydroxynorcaradiene intermediate followed by a series of double bond reductions and dehydrations to the saturated 3.
authors.affiliation: The Department of Chemistry BG-10, University of Washington, Seattle, Washington 98195, and the Botanisches Institut, Mikrobiologie, Universität Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany.
authors.forename: Bradley S.
authors.initials: BS
authors.lastname: Moore
authors.forename: Kevin
authors.initials: K
authors.lastname: Walker
authors.forename: Ingo
authors.initials: I
authors.lastname: Tornus
authors.forename: Sandeep
authors.initials: S
authors.lastname: Handa
authors.forename: Karl
authors.initials: K
authors.lastname: Poralla
authors.forename: Heinz G.
authors.initials: HG
authors.lastname: Floss