Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, Université Pierre et Marie Curie (Paris 6), UR5 EAC7180 CNRS, Case 156, 75005 Paris, France.
Plant Physiol. 2010 Apr;152(4):1851-62. doi: 10.1104/pp.109.152371. Epub 2010 Feb 19.
Mitochondrial carrier family proteins are diverse in their substrate specificity, organellar location, and gene expression. In Arabidopsis (Arabidopsis thaliana), 58 genes encode these six-transmembrane-domain proteins. We investigated the biological role of the basic amino acid carrier Basic Amino Acid Carrier2 (BAC2) from Arabidopsis that is structurally and functionally similar to ARG11, a yeast ornithine and arginine carrier, and to Arabidopsis BAC1. By studying the expression of BAC2 and the consequences of its mutation in Arabidopsis, we showed that BAC2 is a genuine mitochondrial protein and that Arabidopsis requires expression of the BAC2 gene in order to use arginine. The BAC2 gene is induced by hyperosmotic stress (with either 0.2 m NaCl or 0.4 m mannitol) and dark-induced senescence. The BAC2 promoter contains numerous stress-related cis-regulatory elements, and the transcriptional activity of BAC2:beta-glucuronidase is up-regulated by stress and senescence. Under hyperosmotic stress, bac2 mutants express the P5CS1 proline biosynthetic gene more strongly than the wild type, and this correlates with a greater accumulation of Pro. Our data suggest that BAC2 is a hyperosmotic stress-inducible transporter of basic amino acids that contributes to proline accumulation in response to hyperosmotic stress in Arabidopsis.
线粒体载体家族蛋白在其底物特异性、细胞器定位和基因表达方面具有多样性。在拟南芥（Arabidopsis thaliana）中，有 58 个基因编码这些六跨膜域蛋白。我们研究了拟南芥碱性氨基酸载体 Basic Amino Acid Carrier2（BAC2）的生物学作用，该蛋白在结构和功能上与酵母鸟氨酸和精氨酸载体 ARG11 以及拟南芥 BAC1 相似。通过研究 BAC2 的表达及其在拟南芥中的突变后果，我们表明 BAC2 是一种真正的线粒体蛋白，并且拟南芥需要表达 BAC2 基因才能利用精氨酸。BAC2 基因受高渗胁迫（0.2 m NaCl 或 0.4 m 甘露醇）和暗诱导衰老诱导。BAC2 启动子包含许多与应激相关的顺式调控元件，BAC2:β-葡萄糖醛酸酶的转录活性受应激和衰老的上调。在高渗胁迫下，bac2 突变体比野生型更强烈地表达 P5CS1 脯氨酸生物合成基因，这与脯氨酸的积累有关。我们的数据表明，BAC2 是一种高渗胁迫诱导的碱性氨基酸转运体，有助于拟南芥对高渗胁迫的脯氨酸积累。
