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Abstract

BackgroundArginine 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.ResultsHigh-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.ConclusionAtmBAC2 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.

Analysis of Gene Expression Profiles in Leaf Tissues of Cultivated Peanuts and Development of EST-SSR Markers and Gene Discovery

“…This value was lower than those of genomic SSR found in other studies [43–45], but was higher than that tested by using RAPD (6.6%) [46], and AFLP (6.7%) [14]. …”

Non-protein amino acids: plant, soil and ecosystem interactions

“…The α-aminoadipic acid pathway is used in plants and animals to catabolise lysine (Zhu et al 2000). Lysine is degraded by lysine-2-oxoglutarate Smirnoff and Cumbes 1989;Hare et al 1998;Akashi et al 2001;Yokota et al 2002;Rontein et al 2002, Catoni et al 2003Akashi et al 2008 2-amino-4-(2-amino-2-carboxyethyl) thio-butanoic acid…”

“…The enzyme is localised in mitochondria (Catoni et al 2003); ornithine is also synthetised in plastids, where it is further converted to arginine (Funck et al 2008). In plants, diamine putrescine is synthetised directly from ornithine by ornithine decarboxylase (ODC; EC 4.1.1.7) and indirectly from arginine by arginine decarboxylase (ADC; EC 4.1.1.19) (Imanishi et al 1998;Tassoni et al 2000).…”

Transport Pathways—Proton Motive Force Interrelationship in Durum Wheat Mitochondria

“…In Arabidopsis thaliana two basic amino acid carriers (BAC1–2) have been identified: BAC1, involved in arginine/ornithine exchange during mobilization of storage proteins in germinating seeds [17,18], and BAC2, responsible for the transport of arginine, ornithine and citrulline and, therefore, involved in proline, polyamine and alkaloid synthesis or in the shuttling of ammonia between mitochondria and plastids [17–20]. As far as the carnitine transport, the BOU1 carrier identified in Arabidopsis thaliana has been hypothesized to import acetyl-carnitine (generated in peroxisomes from acetyl-CoA) in exchange for carnitine to directly feed the Krebs cycle with acetyl units [21].…”