Microbiology and Cell Science Department , University of Florida, Gainesville, Florida 32611, USA.
Plant Physiol. 2013 Jun;162(2):581-8. doi: 10.1104/pp.113.218081. Epub 2013 Apr 16.
Plants make coenzyme A (CoA) in the cytoplasm but use it for reactions in mitochondria, chloroplasts, and peroxisomes, implying that these organelles have CoA transporters. A plant peroxisomal CoA transporter is already known, but plant mitochondrial or chloroplastic CoA transporters are not. Mitochondrial CoA transporters belonging to the mitochondrial carrier family, however, have been identified in yeast (Saccharomyces cerevisiae; Leu-5p) and mammals (SLC25A42). Comparative genomic analysis indicated that angiosperms have two distinct homologs of these mitochondrial CoA transporters, whereas nonflowering plants have only one. The homologs from maize (Zea mays; GRMZM2G161299 and GRMZM2G420119) and Arabidopsis (Arabidopsis thaliana; At1g14560 and At4g26180) all complemented the growth defect of the yeast leu5Δ mitochondrial CoA carrier mutant and substantially restored its mitochondrial CoA level, confirming that these proteins have CoA transport activity. Dual-import assays with purified pea (Pisum sativum) mitochondria and chloroplasts, and subcellular localization of green fluorescent protein fusions in transiently transformed tobacco (Nicotiana tabacum) Bright Yellow-2 cells, showed that the maize and Arabidopsis proteins are targeted to mitochondria. Consistent with the ubiquitous importance of CoA, the maize and Arabidopsis mitochondrial CoA transporter genes are expressed at similar levels throughout the plant. These data show that representatives of both monocotyledons and eudicotyledons have twin, mitochondrially located mitochondrial carrier family carriers for CoA. The highly conserved nature of these carriers makes possible their reliable annotation in other angiosperm genomes.
植物在细胞质中合成辅酶 A（CoA），但将其用于线粒体、叶绿体和过氧化物酶体中的反应，这意味着这些细胞器具有 CoA 转运蛋白。已经知道一种植物过氧化物酶体 CoA 转运蛋白，但植物线粒体或叶绿体 CoA 转运蛋白尚不清楚。然而，属于线粒体载体家族的酵母（酿酒酵母；Leu-5p）和哺乳动物（SLC25A42）中的线粒体 CoA 转运蛋白已被鉴定。比较基因组分析表明，被子植物有这两种线粒体 CoA 转运蛋白的不同同源物，而非开花植物只有一种。来自玉米（Zea mays；GRMZM2G161299 和 GRMZM2G420119）和拟南芥（Arabidopsis thaliana；At1g14560 和 At4g26180）的同源物均能互补酵母 leu5Δ线粒体 CoA 载体突变体的生长缺陷，并大大恢复其线粒体 CoA 水平，证实这些蛋白具有 CoA 转运活性。使用纯化的豌豆（Pisum sativum）线粒体和叶绿体进行的双重导入测定，以及瞬时转化的烟草（Nicotiana tabacum）Bright Yellow-2 细胞中绿色荧光蛋白融合的亚细胞定位，表明玉米和拟南芥蛋白靶向线粒体。与 CoA 的普遍重要性一致，玉米和拟南芥线粒体 CoA 转运蛋白基因在整个植物中以相似水平表达。这些数据表明，单子叶植物和双子叶植物的代表都具有双，位于线粒体的线粒体载体家族载体用于 CoA。这些载体的高度保守性质使得在其他被子植物基因组中对其进行可靠注释成为可能。
