How Dirigent Proteins Guide Assembly of Lignans and Lignin in Vascular Plants
EMSL Project ID
48403
Abstract
Vascular plants use a class of proteins termed dirigent proteins (from Latin dirigere, to guide or steer) to direct the regio- and stereospecificity of radical-radical coupling reactions of monolignol precursors, such as coniferyl alcohol, in the key reaction forming a class of specialized metabolites called lignans such as pinoresinol and many others. The same monolignols are precursors for lignin, the principal biopolymer responsible for lignocelluloses recalcitrance, and there is growing evidence that dirigent proteins are involved in guiding the stereochemical outcome of monolignol coupling reactions there as well. We have studied dirigent proteins since their discovery in our lab more than fifteen years ago, yet many mysteries about their function remain. Here we propose to use EMSL's capabilities in mass spectrometry, NMR and EPR spectroscopy, and proteomics and metabolomics to understand two key questions surrounding dirigent proteins: 1) what is the nature of the protein-substrate complex--the substrate being the reactive monolignol radical itself--and how does the dirigent protein position this radical with respect to another in a way that specifies one stereochemical outcome over another? And 2) what is implied by the broad sequence diversity across the family of dirigent proteins, i.e. most plants have 10-20 or more dirigent protein paralogues, some with very low sequence similarity, each expressed at varying levels in different tissues--does it mean there is a corresponding diversity of substrates or products, or do the differences lie elsewhere? Both questions are timely in light of the first X-ray structure of a dirigent protein, solved in our lab, that enables these key questions to be asked for the first time.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Corbin C., S. Drouet, L. Markulin, D. Auguin, D. Auguin, E. Laine, and L.B. Davin, et al. 2018. "A genome-wide analysis of the flax (Linum usitatissimum L.) dirigent protein family: from gene identification and evolution to differential regulation." Plant Molecular Biology 97, no. 1-2:73-101. PNNL-SA-131411. doi:10.1007/s11103-018-0725-x
Garcellano R.C., S. Moinuddin, R.P. Young, M.E. Bowden, M. Zhou, R.S. Renslow, and Y. Yesiltepe, et al. 2018. "Isolation of Tryptanthrin and Reassessment of Evidence for its Isobaric Isostere Wrightiadione in Plants of the Wrightia Genus." Journal of Natural Products. PNNL-SA-135279. doi:10.1021/acs.jnatprod.8b00567.
Garcellano R.C., S. Moinuddin, R.P. Young, M.E. Bowden, M. Zhou, R.S. Renslow, and Y. Yesiltepe, et al. 2019. "Isolation of Tryptanthrin and Reassessment of Evidence for its Isobaric Isostere Wrightiadione in Plants of the Wrightia Genus." Journal of Natural Products 82, no. 3:440-448. PNNL-SA-135279. doi:10.1021/acs.jnatprod.8b00567