Expression pattern of a nuclear encoded mitochondrial arginine-ornithine translocator gene from Arabidopsis.
BACKGROUND
Arginine and citrulline serve as nitrogen storage forms, but are also involved in biosynthetic and catabolic pathways. Metabolism of arginine, citrulline and ornithine is distributed between mitochondria and cytosol. For the shuttle of intermediates between cytosol and mitochondria transporters present on the inner mitochondrial membrane are required. Yeast contains a mitochondrial translocator for ornithine and arginine, Ort1p/Arg11p. Ort1p/Arg11p is a member of the mitochondrial carrier family (MCF) essential for ornithine export from mitochondria. The yeast arg11 mutant, which is deficient in Ort1p/Arg11p grows poorly on media lacking arginine.


RESULTS
High-level expression of a nuclear encoded Arabidopsis thaliana homolog (AtmBAC2) of Ort1p/Arg11p was able to suppress the growth deficiency of arg11. RT-PCR analysis demonstrated expression of AtmBAC2 in all tissues with highest levels in flowers. Promoter-GUS fusions showed preferential expression in flowers, i.e. pollen, in the vasculature of siliques and in aborted seeds. Variable expression was observed in leaf vasculature. Induction of the promoter was not observed during the first two weeks in seedlings grown on media containing NH4NO3, arginine or ornithine as sole nitrogen sources.


CONCLUSIONS
AtmBAC2 was isolated as a mitochondrial transporter for arginine in Arabidopsis. The absence of expression in developing seeds and in cotyledons of seedlings indicates that other transporters are responsible for storage and mobilization of arginine in seeds.
Catoni
Elisabetta
E
Plant Physiology, ZMBP, Auf der Morgenstelle 1, D-72076 Tübingen, Germany. elisabetta.catoni@zmbp.uni-tuebingen.de
Desimone
Marcelo
M
Hilpert
Melanie
M
Wipf
Daniel
D
Kunze
Reinhard
R
Schneider
Anja
A
Flügge
Ulf-Ingo
UI
Schumacher
Karin
K
Frommer
Wolf B
WB
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001120:Arginine / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009952:Ornithine / Q000378:metabolism; D010802:Phylogeny; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics
D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011993:Recombinant Fusion Proteins; D001120:Arginine; D009952:Ornithine; D005966:Glucuronidase