Identification and characterization of the BAHD acyltransferase malonyl CoA: anthocyanidin 5-O-glucoside-6''-O-malonyltransferase (At5MAT) in Arabidopsis thaliana.
The major anthocyanin in A. thaliana is a cyanidin derivative modified by glycosylation as well as by the addition of three acyl moieties: malonyl, p-coumaroyl, and sinapoyl. We have isolated a member of the BAHD acyltransferase family which catalyzes this malonylation reaction by combining a reverse genetics approach with biochemical genomics. A mutant line containing a T-DNA insertion in At3g29590, the gene encoding the malonylating enzyme, is incapable of producing malonylated anthocyanins. Transgenic plants harboring an RNAi silencing cassette for At3g29590 demonstrate a positive correlation between reduction in the At3g29590 gene transcript and the decrease of malonylated anthocyanins. Transcript levels for both At3g29590 and the epistatic gene At4g14090, encoding 5-O-anthocyanin glucosyltransferase, increase in several plant lines as they accumulate anthocyanin pigments. Investigation of the heterologously expressed and purified malonylating enzyme showed that the activity is specific for malonyl-CoA and for anthocyanins with 5-O-glucosylation. The malonyl transfer itself occurs only to the 5-O-glucoside function, and not to any of the other sugar moieties present in A. thaliana anthocyanins. Hence, both in vivo and in vitro results define the activity of the At3g29590-encoded enzyme as an anthocyanin 5-O-glucoside-6''-O-malonyltransferase (At5MAT).
D'Auria
John C
JC
Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll Strasse 8, D-07745 Jena, Germany. dauria@ice.mpg.de
Reichelt
Michael
M
Luck
Katrin
K
Svatos
Ales
A
Gershenzon
Jonathan
J
D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D004843:Epistasis, Genetic; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D030821:Plants, Genetically Modified; D034622:RNA Interference; D013379:Substrate Specificity
D000872:Anthocyanins; D000217:Acyltransferases; C445314:malonyl-CoA anthocyanin 5-O-glucoside-6'''-O-malonyltransferase; D005964:Glucosyltransferases; C118149:UDP-glucose anthocyanin 5-O-glucosyltransferase