Mutations in the Arabidopsis gene immutans cause a variegated phenotype by inactivating a chloroplast terminal oxidase associated with phytoene desaturation
Mutations in the Arabidopsis gene immutans cause a variegated phenotype by inactivating a chloroplast terminal oxidase associated with phytoene desaturation
复制标题
DOI：
10.1105/tpc.11.1.57
复制
发表时间：
1999-01-01
期刊：
影响因子：
11.6
通讯作者：
Kuntz, M
中科院分区：
文献类型：
--
作者：
Carol, P;Stevenson, D;Kuntz, M
拟南芥的immutans（im）突变体显示出包括白化病和绿色体细胞区段的杂色表型。我们已经克隆了转座子标签的IM基因，并表明，即使是稳定的无效等位基因引起的杂色表型。该基因产物与线粒体交替氧化酶具有氨基酸相似性。我们表明，IM蛋白是合成的前体多肽，进口到叶绿体和插入到类囊体膜。im植物的白化病部分含有减少水平的类胡萝卜素和增加水平的类胡萝卜素前体八氢番茄红素。这里提供的数据是一致的IM蛋白作为类胡萝卜素去饱和的辅因子的作用。IM的末端氧化酶功能的建议似乎是必不可少的，以防止叶绿体形成的早期步骤中的光氧化损伤。我们提出了一个模型，其中IM功能与八氢番茄红素去饱和，并可能，叶绿体的呼吸活性。
The immutans (im) mutant of Arabidopsis shows a variegated phenotype comprising albino and green somatic sectors. We have cloned the IM gene by transposon tagging and show that even stable null alleles give rise to a variegated phenotype. The gene product has amino acid similarity to the mitochondrial alternative oxidase. We show that the IM protein is synthesized as a precursor polypeptide that is imported into chloroplasts and inserted into the thylakoid membrane. The albino sectors of im plants contain reduced levels of carotenoids and increased levels of the carotenoid precursor phytoene. The data presented here are consistent with a role for the IM protein as a cofactor for carotenoid desaturation. The suggested terminal oxidase function of IM appears to be essential to prevent photooxidative damage during early steps of chloroplast formation. We propose a model in which IM function is linked to phytoene desaturation and, possibly, to the respiratory activity of the chloroplast.