The Strawberry Pathogenesis-related 10 (PR-10) Fra a Proteins Control Flavonoid Biosynthesis by Binding to Metabolic Intermediates

Abstract

Background: Suppression of Fra a gene expression leads to down-regulation of color-producing flavonoid biosynthesis in strawberry.Results: Fra proteins can bind natural flavonoids, which induce conformational changes in conserved loop regions.Conclusion: Fra a proteins control flavonoid biosynthesis through binding to metabolic intermediates.Significance: PR-10 proteins may play a role in the control of secondary metabolism through binding of metabolites to their ligand-binding cavities.

Physical interaction between the strawberry allergen Fra a 1 and an associated partner FaAP: Interaction of Fra a 1 proteins and FaAP

“…Recently, it was shown that Fra a 1.01E is a monomer in solution and in the crystal 3D structure . In this study, the time resolved DNA‐switching measurement system demonstrated dimerization of Fra a 1.01E.…”

“…These results demonstrated that Fra a 1 expression is directly linked to flavonoid biosynthesis and showed that the Fra a 1 allergen has an essential biological function in pigment formation in strawberry fruits . Only recently, the structural analysis of a Fra a 1.03‐catechin complex provided first mechanistic insights into the biological function of Fra a 1 proteins as they may play a role in the control of the flavonoid pathway by binding to metabolic intermediates …”

Overexpression of RSOsPR10, a root-specific rice PR10 gene, confers tolerance against drought stress in rice and drought and salt stresses in bentgrass

“…The PR10 genes, including those of the tree pollen allergens, are present as a multigene family in various seed plants, and are regulated by highly complex signaling systems (Agarwal and Agarwal 2014). Genetic, structural, and bioinformatic studies have revealed a variety of activities for PR10 proteins, including binding to cytokinins (Pasternak et al 2006;Fernandes et al 2008;Zubini et al 2009) and flavonoids (Casañal et al 2013), membrane permeability (Mogensen et al 2007), and norcoclaurine synthase activity (Lee and Facchini 2010). Furthermore, a Bet v1-superfamily has been defined based on protein structural similarities (Radauer et al 2008), and includes the PR10 family and the PYR1/PYL1/RCAR family of abscisic acid receptors (Ma et al 2009).…”

The Pathogenesis Related Class 10 proteins in Plant Defense against Biotic and Abiotic Stresses

“…The difference in binding activity pointed towards the differences in the binding pockets based on homology modeling. PR-10 proteins have structural and sequence homology with mammalian lipid transport and plant abscisic acid receptor proteins and are predicted to have cavities for ligand binding [61]. A large internal Y-shaped hydrophobic cavity, as determined by three-dimensional structure of PR-10 proteins could be liable for transport of a polar ligands such as fatty acids, flavonoids, cytokinins or brassino steroids in the intracellular spaces [62].…”

“…In a recently study, three new members of the PR-10 family, the Fra a proteins, have been identified in strawberry in response to the flavonoid biosynthesis pathway, which is essential for the development of color and flavor in fruits and it was suggested that Fra a proteins could act as transporters or "chemical chaperones" binding to flavonoid intermediates so that they are available to processing enzymes [61]. Furthermore, structural comparisons of the apo forms of Fra a 1E and the Fra a 3-catechin complex indicates that Fra a proteins show significant flexibility in the loop regions surrounding the cavity (loops L3, L5, and L7) and ligandbinding induces important conformational changes suggesting an important role of PR-10 proteins in control of secondary metabolic pathways.…”