The Poly-Glutamate Motif of GmMATE4 Regulates Its Isoflavone Transport Activity

Abstract

Multidrug and toxic compound extrusion (MATE) transporters in eukaryotes have been characterized to be antiporters that mediate the transport of substrates in exchange for protons. In plants, alkaloids, phytohormones, ion chelators, and flavonoids have been reported to be the substrates of MATE transporters. Structural analyses have been conducted to dissect the functional significance of various motifs of MATE proteins. However, an understanding of the functions of the N- and C-termini has been inadequate. Here, by performing phylogenetic analyses and protein sequence alignment of 14 representative plant species, we identified a distinctive N-terminal poly-glutamate motif among a cluster of MATE proteins in soybean. Amongst them, GmMATE4 has the most consecutive glutamate residues at the N-terminus. A subcellular localization study showed that GmMATE4 was localized at the vacuolar membrane-like structure. Protein charge prediction showed that the mutation of the glutamate residues to alanine would reduce the negative charge at the N-terminus. Using yeast as the model, we showed that GmMATE4 mediated the transport of daidzein, genistein, glycitein, and glycitin. In addition, the glutamate-to-alanine mutation reduced the isoflavone transport capacity of GmMATE4. Altogether, we demonstrated GmMATE4 as an isoflavone transporter and the functional significance of the N-terminal poly-glutamate motif of GmMATE4 for regulating the isoflavone transport activity.

The Role of Anthocyanins in Plant Tolerance to Drought and Salt Stresses

“…Competition between FLS and DFR regulates flavonol synthesis or anthocyanin accumulation, respectively. DFR is the key enzyme in anthocyanin biosynthesis, it converts dihydrokaempferol, converts dihydrokaempferol, dihydroquercetin, or dihydromyricetin (DHK, DHQ or DHM, respectively) into leucoanthocyanidins, which are further converted by ANS into other anthocyanidins, modified by glycosylation, acylation, and methylation (Figure 1) [4] and transported by GST and the multidrug and toxic compound extrusion (MATE) transport system into the vacuole [5][6][7]. There are hundreds of unique anthocyanins and many enzymes involved in their modifications; however, these late modification pathways are mostly unknown [8].…”

Preferential transport activity of DkDTX5/MATE5 affects the formation of different astringency in persimmon

“…For example, MtMATE2 can transport diverse types of flavonoids (Zhao et al, 2011). The specificity of the DTX/MATE transport substrate varies with the amino acid residues (Ku et al, 2022). Moreover, we found two alleles of DkDTX5/MATE5 in the A‐type, in which the dominantly expressed DkDTX5/MATE5‐2 A gene lacked the transport function.…”

Biosynthesis and metabolic engineering of isoflavonoids in model plants and crops: a review

“…In soybean, GmMATE1, GmMATE2, and GmMATE4, localized in the vacuolar membrane, are implicated in transporting isoflavones for accumulation through yeast uptake assay. In addition, it has also been confirmed that the total isoflavone content in seeds is significantly increased due to the overexpression of GmMATE1 in transgenic soybean, while it is significantly decreased due to GmMATE1 mutation (Ng et al, 2021;Ku et al, 2022). The utilization of maize GST-mediated conjugation with GSH (medicarpin-GS) significantly enhances the uptake of isoflavonoids by vacuoles (Li et al, 1997).…”