Tapetum-specific location of a cation-dependent O-methyltransferase in Arabidopsis thaliana.
Cation- and S-adenosyl-L-methionine (AdoMet)-dependent plant natural product methyltransferases are referred to as CCoAOMTs because of their preferred substrate, caffeoyl coenzyme A (CCoA). The enzymes are encoded by a small family of genes, some of which with a proven role in lignin monomer biosynthesis. In Arabidopsis thaliana individual members of this gene family are temporally and spatially regulated. The gene At1g67990 is specifically expressed in flower buds, and is not detected in any other organ, such as roots, leaves or stems. Several lines of evidence indicate that the At1g67990 transcript is located in the flower buds, whereas the corresponding CCoAOMT-like protein, termed AtTSM1, is located exclusively in the tapetum of developing stamen. Flowers of At1g67990 RNAi-suppressed plants are characterized by a distinct flower chemotype with severely reduced levels of the N ',N ''-bis-(5-hydroxyferuloyl)-N '''-sinapoylspermidine compensated for by N(1),N(5),N(10)-tris-(5-hydroxyferuloyl)spermidine derivative, which is characterized by the lack of a single methyl group in the sinapoyl moiety. This severe change is consistent with the observed product profile of AtTSM1 for aromatic phenylpropanoids. Heterologous expression of the recombinant protein shows the highest activity towards a series of caffeic acid esters, but 5-hydroxyferuloyl spermidine conjugates are also accepted substrates. The in vitro substrate specificity and the in vivo RNAi-mediated suppression data of the corresponding gene suggest a role of this cation-dependent CCoAOMT-like protein in the stamen/pollen development of A. thaliana.
Fellenberg
Christin
C
Department of Secondary Metabolism, Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany.
Milkowski
Carsten
C
Hause
Bettina
B
Lange
Peter-Robert
PR
Böttcher
Christoph
C
Schmidt
Jürgen
J
Vogt
Thomas
T
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002109:Caffeic Acids / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D013058:Mass Spectrometry; D008780:Methyltransferases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics; D011073:Polyamines / Q000378:metabolism; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013379:Substrate Specificity; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D002109:Caffeic Acids; D018076:DNA, Complementary; D011073:Polyamines; D018749:RNA, Plant; D008780:Methyltransferases; C059825:caffeoyl-CoA O-methyltransferase