Steinmüller K, Ley A C, Steinmetz A A, Sayre R T, Bogorad L
Biological Laboratories, Harvard University, Cambridge, MA 02138.
Mol Gen Genet. 1989 Mar;216(1):60-9. doi: 10.1007/BF00332231.
The ndhC and ORF159 genes of the maize plastid DNA (ptDNA) were sequenced and maize ORF159 was used to screen a library of genomic DNA of the blue-green alga Synechocystis sp. PCC 6803. The cyanobacterial gene homologous to ORF159 (ORF157) was isolated and sequenced. In sequencing the region upstream of ORF157, reading frames with homology to the ndhC and psbG genes of maize ptDNA were identified. The ndhC and psbG genes overlap in the ptDNAs of maize, tobacco and Marchantia polymorpha, but are separated by a noncoding spacer in Synechocystis. Northern blot analysis showed that the ndhC, psbG and ORF157/159 genes are cotranscribed in maize and Synechocystis. The three genes occur in the same order in ptDNA of maize, tobacco, and M. polymorpha as in Synechocystis 6803. The amino acid sequences of the NDH-C, PSII-G and the ORF157/159 proteins deduced from the maize genes are 65%, 52% and 53% homologous to those of Synechocystis. However, the cyanobacterial and higher plant NDH-C protein sequences are only 23% homologous to the mitochondrial NDH-3 protein. Protein products of in vitro transcription/translation of the Synechocystis transcription unit had apparent molecular masses of 6 kDa (NDH-C), 25 kDa (PSII-G) and 22 kDa (ORF157) on lithium dodecyl sulfate (LDS) polyacrylamide gel electrophoresis. If these are components of an NADH dehydrogenase, cyanobacteria appear to resemble mitochondria more than they do Escherichia coli and Rhodopseudomonas capsulata with regard to this enzyme complex.
对玉米质体DNA（ptDNA）的ndhC和ORF159基因进行了测序，并利用玉米ORF159筛选了蓝藻集胞藻PCC 6803的基因组DNA文库。分离并测序了与ORF159同源的蓝藻基因（ORF157）。在对ORF157上游区域进行测序时，鉴定出了与玉米ptDNA的ndhC和psbG基因具有同源性的阅读框。ndhC和psbG基因在玉米、烟草和地钱的ptDNA中重叠，但在集胞藻中被一个非编码间隔区分开。Northern印迹分析表明，ndhC、psbG和ORF157/159基因在玉米和集胞藻中是共转录的。这三个基因在玉米、烟草和地钱的ptDNA中的排列顺序与集胞藻6803中的相同。从玉米基因推导的NDH-C、PSII-G和ORF157/159蛋白的氨基酸序列与集胞藻的相应序列同源性分别为65%、52%和53%。然而，蓝藻和高等植物的NDH-C蛋白序列与线粒体NDH-3蛋白的同源性仅为23%。集胞藻转录单元的体外转录/翻译产物在十二烷基硫酸锂（LDS）聚丙烯酰胺凝胶电泳上的表观分子量分别为6 kDa（NDH-C）、25 kDa（PSII-G）和22 kDa（ORF157）。如果这些是NADH脱氢酶的组成部分，那么就这种酶复合物而言，蓝藻似乎更类似于线粒体，而不是大肠杆菌和荚膜红假单胞菌。
