Molecular and immunological analysis of an ABC transporter complex required for cytochrome c biogenesis
Molecular and immunological analysis of an ABC transporter complex required for cytochrome c biogenesis
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DOI：
10.1006/jmbi.1997.0992
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发表时间：
1997-05-16
影响因子：
5.6
通讯作者：
Kranz, RG
中科院分区：
文献类型：
--
作者：
Goldman, BS;Beckman, DL;Kranz, RG
据预测，helABC基因编码一个三磷酸腺苷结合盒(ABC)转运体，在细菌细胞色素c的生物发生中，连接血红素是输出血红素所必需的。最近发现的Helb同源基因和。植物线粒体基因组中的helC基因表明，这是一种在原核生物和一些真核生物中高度保守的转运蛋白，其中HelB和HelC蛋白构成跨膜成分。对革兰氏阴性菌的分子遗传学分析表明，helABC和helDX基因是与secDF基因连锁的操纵子的一部分。为了便于对这种转运蛋白的分析，产生了每个基因、表位和报告标记的HelABCD蛋白以及针对HeLa和HelX蛋白的抗血清的非极性缺失的菌株。我们直接证明了这种转运蛋白以HeLABCD复合体的形式存在于细胞膜中。HelB和HelC是HeLa蛋白结合和稳定所必需的，HelB和HelC是含有ATP结合区的细胞质亚基。此外，我们还发现HeLa蛋白与HelC或保持蛋白共沉淀。因此，HelABCD血红素出口复合体的区别在于存在四个与膜相关的亚单位，并代表了ABC转运蛋白的一个独特的亚家族。(C)1997年学术出版社有限公司。
The helABC genes are predicted to encode an ATP-binding cassette (ABC) transporter necessary for heme export for ligation in bacterial cytochrome c biogenesis. The recent discoveries of homologs of the helB and. helC genes in plant mitochondrial genomes suggest this is a highly conserved transporter in prokaryotes and some eukaryotes with the HelB and HelC proteins comprising the transmembrane components. Molecular genetic analysis in the Gram-negative bacterium Rhodobacter capsulatus was used to show that the helABC and helDX genes are part of an operon linked to the secDF genes. To facilitate analysis of this transporter, strains with non-polar deletions in each gene, epitope and reporter-tagged HelABCD proteins, and antisera specific to the HelA and HelX proteins were generated. We directly demonstrate that this transporter is present in the cytoplasmic membrane as an HeLABCD complex. The HelB and HelC but not HelD proteins are necessary for the binding and stability of the HelA protein, the cytoplasmic subunit containing the ATP-binding region. In addition we show that the HelA protein co-immunoprecipitates with either the HelC or HelD proteins. Thus, the HelABCD heme export complex is distinguished by the presence of four membrane-associated subunits and represents a unique subfamily of ABC transporters. (C) 1997 Academic Press Limited.