Campus Units

Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

9-4-2019

Journal or Book Title

Biochemical Journal

DOI

10.1042/BCJ20190479

Abstract

All land plants contain at least one class II diterpene cyclase (DTC), which utilize an acid-base catalytic mechanism, for the requisite production of ent -copalyl diphosphate ( ent -CPP) in gibberellin A (GA) phytohormone biosynthesis. These ent -CPP synthases (CPSs) are hypothesized to be derived from ancient bacterial origins and, in turn, to have given rise to the frequently observed additional DTCs utilized in more specialized plant metabolism. However, such gene duplication and neo-functionalization has occurred repeatedly, reducing the utility of phylogenetic analyses. Support for evolutionary scenarios can be found in more specific conservation of key enzymatic features. While DTCs generally utilize a DxDD motif as the catalytic acid, the identity of the catalytic base seems to vary depending, at least in part, on product outcome. The CPS from Arabidopsis thaliana has been found to utilize a histidine-asparagine dyad to ligate a water molecule that serves as the catalytic base, with alanine substitution leading to production of 8b-hydroxy- ent -CPP. Here this dyad and effect of Ala substitution is shown to be specifically conserved in plant CPSs involved in GA biosynthesis, providing insight into plant DTC evolution and assisting functional assignment. Even more strikingly, while GA biosynthesis arose independently in plant-associated bacteria and fungi, the catalytic base dyad also is specifically found in the relevant bacterial, but not fungal, CPSs. This suggests functional conservation of CPSs from bacteria to plants, presumably reflecting an early role for derived diterpenoids in both plant development and plant-microbe interactions, eventually leading to GA, and a speculative evolutionary scenario is presented.

Comments

This is a manuscript of an article published as Lemke, Cody, Kevin C. Potter, Samuel Schulte, and Reuben J. Peters. "Conserved bases for the initial cyclase in gibberellin biosynthesis: from bacteria to plants." Biochemical Journal (2019). doi: 10.1042/BCJ20190479. Posted with permission.

Copyright Owner

The Authors

Language

en

File Format

application/pdf

Available for download on Friday, September 04, 2020

Published Version

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