Cross-talk between the cytosolic mevalonate and the plastidial methylerythritol phosphate pathways in tobacco bright yellow-2 cells.
In plants, two pathways are utilized for the synthesis of isopentenyl diphosphate, the universal precursor for isoprenoid biosynthesis. The key enzyme of the cytoplasmic mevalonic acid (MVA) pathway is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). Treatment of Tobacco Bright Yellow-2 (TBY-2) cells by the HMGR-specific inhibitor mevinolin led to growth reduction and induction of apparent HMGR activity, in parallel to an increase in protein representing two HMGR isozymes. Maximum induction was observed at 24 h. 1-Deoxy-d-xylulose (DX), the dephosphorylated first precursor of the plastidial 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway, complemented growth inhibition by mevinolin in the low millimolar concentration range. Furthermore, DX partially re-established feedback repression of mevinolin-induced HMGR activity. Incorporation studies with [1,1,1,4-2H4]DX showed that sterols, normally derived from MVA, in the presence of mevinolin are synthesized via the MEP pathway. Fosmidomycin, an inhibitor of 1-deoxy-d-xylulose-5-phosphate reductoisomerase, the second enzyme of the MEP pathway, was utilized to study the reverse complementation. Growth inhibition by fosmidomycin of TBY-2 cells could be partially overcome by MVA. Chemical complementation was further substantiated by incorporation of [2-13C]MVA into plastoquinone, representative of plastidial isoprenoids. Best rates of incorporation of exogenous stably labeled precursors were observed in the presence of both inhibitors, thereby avoiding internal isotope dilution.
CNRS, UPR 2357, Institut de Biologie Moléculaire des Plantes, 28 Rue Goethe, 67083 Strasbourg Cedex, France.
Andréa
A
Hemmerlin
Jean-François
JF
Hoeffler
Odile
O
Meyer
Denis
D
Tritsch
Isabelle A
IA
Kagan
Catherine
C
Grosdemange-Billiard
Michel
M
Rohmer
Thomas J
TJ
Bach
D003600:Cytosol / Q000378:metabolism; D004896:Erythritol / Q000031:analogs & derivatives* / Q000378:metabolism*; D005578:Fosfomycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D008148:Lovastatin / Q000494:pharmacology; D008798:Mevalonic Acid / Q000378:metabolism*; D010840:Phytosterols / Q000096:biosynthesis; D018087:Plastids / Q000378:metabolism; D010971:Plastoquinone / Q000378:metabolism; D015398:Signal Transduction; D013403:Sugar Phosphates / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014996:Xylulose / Q000031:analogs & derivatives* / Q000494:pharmacology
C114232:2-C-methylerythritol 4-phosphate; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D010840:Phytosterols; D013403:Sugar Phosphates; D005578:Fosfomycin; C024640:fosmidomycin; D014996:Xylulose; C029724:1-deoxy-2-pentulose; D008148:Lovastatin; D006903:Hydroxymethylglutaryl CoA Reductases; D010971:Plastoquinone; D004896:Erythritol; D008798:Mevalonic Acid