The biosynthetic gene cluster for the cyanogenic glucoside dhurrin in Sorghum bicolor contains its co-expressed vacuolar MATE transporter

Abstract

Genomic gene clusters for the biosynthesis of chemical defence compounds are increasingly identified in plant genomes. We previously reported the independent evolution of biosynthetic gene clusters for cyanogenic glucoside biosynthesis in three plant lineages. Here we report that the gene cluster for the cyanogenic glucoside dhurrin in Sorghum bicolor additionally contains a gene, SbMATE2, encoding a transporter of the multidrug and toxic compound extrusion (MATE) family, which is co-expressed with the biosynthetic genes. The predicted localisation of SbMATE2 to the vacuolar membrane was demonstrated experimentally by transient expression of a SbMATE2-YFP fusion protein and confocal microscopy. Transport studies in Xenopus laevis oocytes demonstrate that SbMATE2 is able to transport dhurrin. In addition, SbMATE2 was able to transport non-endogenous cyanogenic glucosides, but not the anthocyanin cyanidin 3-O-glucoside or the glucosinolate indol-3-yl-methyl glucosinolate. The genomic co-localisation of a transporter gene with the biosynthetic genes producing the transported compound is discussed in relation to the role self-toxicity of chemical defence compounds may play in the formation of gene clusters.

Global analysis of the MATE gene family of metabolite transporters in tomato

“…This result is significant, given the recent interest in breeding vegetables for high-nutrient density [ 11 ]. Also in this clade is SbMATE2 from sorghum, which transports toxic hydroxynitrile glucosides (e.g., dhurrin) to the vacuole of cells in diverse tissues of the plant [ 53 ].…”

Biosynthesis of cyanogenic glucosides in Phaseolus lunatus and the evolution of oxime‐based defenses

“…Analysis of the L. japonicus genome revealed that the biosynthetic genes for linamarin and lotaustralin are organized in a biosynthetic gene cluster and helped identify CYP736A2 as responsible for the second enzymatic step (Takos et al, 2011). We also reported the existence of biosynthetic gene clusters for cyanogenic glucosides in the genomes of cassava and sorghum, of which the latter was shown to contain additionally a vacuolar MATE-type transporter for dhurrin (Darbani et al, 2016). A gene cluster in barley (Hordeum vulgare) contains the CYP79 and CYP71 genes that encode the enzymes for the production of five leucine-derived α-, β-, and γ-hydroxynitrile glucosides, including the cyanogenic glucoside epiheterodendrin (Knoch, Motawie, Olsen, Møller, & Lyngkjaer, 2016).…”

Multi‐omics data‐driven investigations of metabolic diversity of plant triterpenoids

“…For example, a transporter from the multidrug and toxic compound extrusion (MATE) family identified within the monoterpene indole alkaloid (MIA) gene cluster is involved in translocation of the intermediates of the MIA pathway (Kellner et al ., ). In sorghum, the vascular membrane protein SbMATE2 is co‐located with the cluster genes and able to transport dhurrin (Darbani et al ., ). Based on the fact that plants are likely to need transporters to translocate specialized metabolites to the right locations, identification and characterization of the transporters involved in counteracting the toxicity or unpleasant flavors conferred by the defensive compounds could provide key knowledge for improving crop quality and also simplify the procedure of metabolic engineering of natural plant products by pumping target compounds out of plant cells or microbes (Xiao and Zhong, ).…”