title: Farnesylation mediates brassinosteroid biosynthesis to regulate abscisic acid responses.
abstract: Protein farnesylation is a post-translational modification involving the addition of a 15-carbon farnesyl isoprenoid to the carboxy terminus of select proteins(1-3). Although the roles of this lipid modification are clear in both fungal and animal signalling, many of the mechanistic functions of farnesylation in plant signalling are still unknown. Here, we show that CYP85A2, the cytochrome P450 enzyme that performs the last step in brassinosteroid biosynthesis (conversion of castasterone to brassinolide)(4), must be farnesylated to function in Arabidopsis. Loss of either CYP85A2 or CYP85A2 farnesylation results in reduced brassinolide accumulation and increased plant responsiveness to the hormone abscisic acid (ABA) and overall drought tolerance, explaining previous observations(5). This result not only directly links farnesylation to brassinosteroid biosynthesis but also suggests new strategies to maintain crop yield under challenging climatic conditions.
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada.
authors.forename: Julian G B
authors.initials: JG
authors.lastname: Northey
authors.affiliation: Department of Biological Sciences, University of Calgary, BI 392, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Siyu
authors.initials: S
authors.lastname: Liang
authors.affiliation: Department of Biological Sciences, University of Calgary, BI 392, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Jamshed
authors.affiliation: Department of Biological Sciences, University of Calgary, BI 392, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Srijani
authors.initials: S
authors.lastname: Deb
authors.affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
authors.forename: Eloise
authors.initials: E
authors.lastname: Foo
authors.affiliation: School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
authors.forename: James B
authors.initials: JB
authors.lastname: Reid
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: McCourt
authors.affiliation: Department of Biological Sciences, University of Calgary, BI 392, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Marcus A
authors.identifier: 0000-0002-3936-5563
authors.initials: MA
authors.lastname: Samuel
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D060406:Brassinosteroids / Q000096:biosynthesis*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D054876:Prenylation
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D003577:Cytochrome P-450 Enzyme System; C474079:brassinosteroid-6 oxidase 2, Arabidopsis