Disruption of adenosine-5'-phosphosulfate kinase in Arabidopsis reduces levels of sulfated secondary metabolites.
Plants can metabolize sulfate by two pathways, which branch at the level of adenosine 5'-phosphosulfate (APS). APS can be reduced to sulfide and incorporated into Cys in the primary sulfate assimilation pathway or phosphorylated by APS kinase to 3'-phosphoadenosine 5'-phosphosulfate, which is the activated sulfate form for sulfation reactions. To assess to what extent APS kinase regulates accumulation of sulfated compounds, we analyzed the corresponding gene family in Arabidopsis thaliana. Analysis of T-DNA insertion knockout lines for each of the four isoforms did not reveal any phenotypical alterations. However, when all six combinations of double mutants were compared, the apk1 apk2 plants were significantly smaller than wild-type plants. The levels of glucosinolates, a major class of sulfated secondary metabolites, and the sulfated 12-hydroxyjasmonate were reduced approximately fivefold in apk1 apk2 plants. Although auxin levels were increased in the apk1 apk2 mutants, as is the case for most plants with compromised glucosinolate synthesis, typical high auxin phenotypes were not observed. The reduction in glucosinolates resulted in increased transcript levels for genes involved in glucosinolate biosynthesis and accumulation of desulfated precursors. It also led to great alterations in sulfur metabolism: the levels of sulfate and thiols increased in the apk1 apk2 plants. The data indicate that the APK1 and APK2 isoforms of APS kinase play a major role in the synthesis of secondary sulfated metabolites and are required for normal growth rates.
Mugford
Sarah G
SG
Department of Metabolic Biology, John Ines Centre, Norwich, Norfolk NR4 7UH, United Kingdom.
Yoshimoto
Naoko
N
Reichelt
Michael
M
Wirtz
Markus
M
Hill
Lionel
L
Mugford
Sam T
ST
Nakazato
Yoshimi
Y
Noji
Masaaki
M
Takahashi
Hideki
H
Kramell
Robert
R
Gigolashvili
Tamara
T
Flügge
Ulf-Ingo
UI
Wasternack
Claus
C
Gershenzon
Jonathan
J
Hell
Rüdiger
R
Saito
Kazuki
K
Kopriva
Stanislav
S
D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000737:chemistry / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D054883:Oxylipins / Q000737:chemistry / Q000378:metabolism; D010641:Phenotype; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism; D014018:Tissue Distribution
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D007210:Indoleacetic Acids; D007527:Isoenzymes; D054883:Oxylipins; D011993:Recombinant Fusion Proteins; D013431:Sulfates; D013438:Sulfhydryl Compounds; C011006:jasmonic acid; D013455:Sulfur; D017853:Phosphotransferases (Alcohol Group Acceptor); C019617:adenylylsulfate kinase