Quantitative exploration of the catalytic landscape separating divergent plant sesquiterpene synthases

Paul E. O'Maille, Arthur Malone, Nikki Dellas, B. Andes Hess, Lidia Smentek, Iseult Sheehan, Bryan T. Greenhagen, Joe Chappell, Gerard Manning, Joseph P. Noel

Research output: Contribution to journalArticlepeer-review

149 Scopus citations

Abstract

Throughout molecular evolution, organisms create assorted chemicals in response to varying ecological niches. Catalytic landscapes underlie metabolic evolution, wherein mutational steps alter the biosynthetic properties of enzymes. Here we report the first systematic quantitative characterization of the catalytic landscape underlying the evolution of sesquiterpene chemical diversity. On the basis of our previous discovery of a set of nine naturally occurring amino acid substitutions that functionally interconverted orthologous sesquiterpene synthases from Nicotiana tabacum and Hyoscyamus muticus, we created a library of all possible residue combinations (29 = 512) in the N. tabacum enzyme. The product spectra of 418 active enzymes revealed a rugged landscape where several minimal combinations of the nine mutations encode convergent solutions to the interconversions of parental activities. Quantitative comparisons indicated context dependence for mutational effects - epistasis - in product specificity and promiscuity. These results provide a measure of the mutational accessibility of phenotypic variability in a diverging lineage of terpene synthases.

Original languageEnglish
Pages (from-to)617-623
Number of pages7
JournalNature Chemical Biology
Volume4
Issue number10
DOIs
StatePublished - Oct 2008

Bibliographical note

Funding Information:
We thank M. Austin and J. Melnick for critical review of the manuscript, Y. Zhai for computational support and J. Gullberg and A. Nordstom for insightful discussions. This work was supported by National Institutes of Health grant GM54029 to J.C. and J.P.N. J.P.N. is supported by the Howard Hughes Medical Institute.

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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