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Science 6 April 2007:
Vol. 316. no. 5821, pp. 73 - 76
DOI: 10.1126/science.1137786
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Research Articles

Chimeras of Two Isoprenoid Synthases Catalyze All Four Coupling Reactions in Isoprenoid Biosynthesis

Hirekodathakallu V. Thulasiram,* Hans K. Erickson,{dagger} C. Dale Poulter{ddagger}

The carbon skeletons of over 55,000 naturally occurring isoprenoid compounds are constructed from four fundamental coupling reactions: chain elongation, cyclopropanation, branching, and cyclobutanation. Enzymes that catalyze chain elongation and cyclopropanation are well studied, whereas those that catalyze branching and cyclobutanation are unknown. We have catalyzed the four reactions with chimeric proteins generated by replacing segments of a chain-elongation enzyme with corresponding sequences from a cyclopropanation enzyme. Stereochemical and mechanistic considerations suggest that the four coupling enzymes could have evolved from a common ancestor through relatively small changes in the catalytic site.

Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, UT 84112, USA.

* Present address: Division of Organic Chemistry, National Chemical Laboratory, Pune 411008, India.

{dagger} Present address: ImmunoGen Incorporated, 128 Sidney Street, Cambridge, MA 02139, USA.

{ddagger} To whom correspondence should be addressed. E-mail: poulter{at}chemistry.utah.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Enzymatic synthesis of a bicyclobutane fatty acid by a hemoprotein lipoxygenase fusion protein from the cyanobacterium Anabaena PCC 7120.
C. Schneider, K. Niisuke, W. E. Boeglin, M. Voehler, D. F. Stec, N. A. Porter, and A. R. Brash (2007)
PNAS 104, 18941-18945
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Science. ISSN 0036-8075 (print), 1095-9203 (online)