Buzan J M, Low R L
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
Biochem Biophys Res Commun. 1988 Apr 15;152(1):22-9. doi: 10.1016/s0006-291x(88)80674-0.
The RNA polymerase of HeLa cell mitochondria has been purified free of endonuclease and DNA topoisomerase activities, permitting evaluation of the effect of template topology on transcription in vitro. On single-stranded DNA templates, transcription is nonspecific and does not require mitochondrial DNA sequences. In contrast, duplex DNA templates are efficiently transcribed only when they (1) carry the mitochondrial D-loop region and (2) are negatively supercoiled. These findings suggest a role for template superhelicity in modulating mitochondrial transcription in vivo.
已纯化出不含核酸内切酶和DNA拓扑异构酶活性的海拉细胞线粒体RNA聚合酶，从而能够评估模板拓扑结构对体外转录的影响。在单链DNA模板上，转录是非特异性的，不需要线粒体DNA序列。相比之下，双链DNA模板只有在满足以下两个条件时才能高效转录：（1）携带线粒体D环区域；（2）呈负超螺旋状态。这些发现表明模板超螺旋在体内调节线粒体转录过程中发挥作用。
