Expression and molecular analysis of the Arabidopsis DXR gene encoding 1-deoxy-D-xylulose 5-phosphate reductoisomerase, the first committed enzyme of the 2-C-methyl-D-erythritol 4-phosphate pathway.
1-Deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) catalyzes the first committed step of the 2-C-methyl-D-erythritol 4-phosphate pathway for isoprenoid biosynthesis. In Arabidopsis, DXR is encoded by a single-copy gene. We have cloned a full-length cDNA corresponding to this gene. A comparative analysis of all plant DXR sequences known to date predicted an N-terminal transit peptide for plastids, with a conserved cleavage site, and a conserved proline-rich region at the N terminus of the mature protein, which is not present in the prokaryotic DXR homologs. We demonstrate that Arabidopsis DXR is targeted to plastids and localizes into chloroplasts of leaf cells. The presence of the proline-rich region in the mature Arabidopsis DXR was confirmed by detection with a specific antibody. A proof of the enzymatic function of this protein was obtained by complementation of an Escherichia coli mutant defective in DXR activity. The expression pattern of beta-glucuronidase, driven by the DXR promoter in Arabidopsis transgenic plants, together with the tissue distribution of DXR transcript and protein, revealed developmental and environmental regulation of the DXR gene. The expression pattern of the DXR gene parallels that of the Arabidopsis 1-deoxy-D-xylulose 5-phosphate synthase gene, but the former is slightly more restricted. These genes are expressed in most organs of the plant including roots, with higher levels in seedlings and inflorescences. The block of the 2-C-methyl-D-erythritol 4-phosphate pathway in Arabidopsis seedlings with fosmidomycin led to a rapid accumulation of DXR protein, whereas the 1-deoxy-D-xylulose 5-phosphate synthase protein level was not altered. Our results are consistent with the participation of the Arabidopsis DXR gene in the control of the 2-C-methyl-D-erythritol 4-phosphate pathway.
Departament de Bioquímica i Biologia Molecular, Facultat de Química, Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain.
Lorenzo
L
Carretero-Paulet
Iván
I
Ahumada
Nuria
N
Cunillera
Manuel
M
Rodríguez-Concepción
Albert
A
Ferrer
Albert
A
Boronat
Narciso
N
Campos
D019747:Aldose-Ketose Isomerases / Q000235:genetics*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004896:Erythritol / Q000031:analogs & derivatives* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics*; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D011106:Polyisoprenyl Phosphates / Q000096:biosynthesis; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D013403:Sugar Phosphates / Q000378:metabolism*
C114232:2-C-methylerythritol 4-phosphate; D029681:Arabidopsis Proteins; D009097:Multienzyme Complexes; D011106:Polyisoprenyl Phosphates; D013403:Sugar Phosphates; D010088:Oxidoreductases; C114231:1-deoxy-D-xylulose 5-phosphate reductoisomerase; D019747:Aldose-Ketose Isomerases; D004896:Erythritol