The plastidic bile acid transporter 5 is required for the biosynthesis of methionine-derived glucosinolates in Arabidopsis thaliana.
Aliphatic glucosinolate biosynthesis is highly compartmentalized, requiring import of 2-keto acids or amino acids into chloroplasts for side chain elongation and export of the resulting compounds into the cytosol for conversion into glucosinolate. Aliphatic glucosinolate biosynthesis in Arabidopsis thaliana is regulated by three R2R3-MYB transcription factors, the major player being High Aliphatic Glucosinolate 1 (HAG1/MYB28). Here, we show that BAT5, which belongs to the putative bile acid transporter family, is the only member of this family that is transactivated by HAG1/MYB28, HAG2/MYB76, and HAG3/MYB29. Furthermore, two isopropylmalate isomerases genes, IPMI1 and IPMI2, and the isopropylmalate dehydrogenase gene, IPMDH1, were identified as targets of HAG1/MYB28 and the corresponding proteins localized to plastids, suggesting a role in plastidic chain elongation reactions. The BAT proteins also localized to plastids; however, only mutants defective in BAT5 function contained strongly reduced levels of aliphatic glucosinolates. The bat5 mutant chemotype was rescued by induced overexpression of BAT5. Feeding experiments using 2-keto acids and amino acids of different chain length suggest that BAT5 is a plastidic transporter of (chain-elongated) 2-keto acids. Mechanical stimuli and methyl jasmonate transiently induced BAT5 expression in inflorescences and leaves. Thus, BAT5 was identified as the first transporter component of the aliphatic glucosinolate biosynthetic pathway.
Gigolashvili
Tamara
T
Botanisches Institut der Universität zu Köln, D-50931 Köln, Germany.
Yatusevich
Ruslan
R
Rollwitz
Inga
I
Humphry
Melanie
M
Gershenzon
Jonathan
J
Flügge
Ulf-Ingo
UI
D000085:Acetates / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002736:Chloroplasts / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D035264:Flowers / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005961:Glucosinolates / Q000096:biosynthesis*; D051548:Histone Acetyltransferases; D007651:Keto Acids / Q000378:metabolism; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D054883:Oxylipins / Q000494:pharmacology; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D000099224:p300-CBP-Associated Factor
D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D005961:Glucosinolates; D051548:Histone Acetyltransferases; D007651:Keto Acids; D029363:Organic Anion Transporters, Sodium-Dependent; D054883:Oxylipins; D014157:Transcription Factors; C544387:BAT5 protein, Arabidopsis; C072239:methyl jasmonate; C474636:GCN5 protein, Arabidopsis; D000099224:p300-CBP-Associated Factor