闭环线粒体DNA的三级结构与功能及其体内转录

Tertiary structure and function of closed-circular mitochondrial DNA and its transcription in vivo.

作者信息

Rastogi A K, Erlinger R F, Koch J

出版信息

Eur J Biochem. 1975 Sep 1;57(1):257-63. doi: 10.1111/j.1432-1033.1975.tb02297.x.

DOI:10.1111/j.1432-1033.1975.tb02297.x

Abstract

The conformation of the closed circular mitochondrial DNA in cultured human cells is changed by the addition of berenil to the culture medium in such a way that the 34-S mitochondrial DNA is converted into a 29-S DNA and finally into a 24-S DNA. The superhelix density of the covalently closed 29-S mitochondrial DNA is sigma O = -1.5 times 10(-2) (turns/10 base pairs) and consequently is intermediate between the superhelix density of the 34-S DNA (sigma0 = -2.8 times 10(-2)) and that of the closed circular 24-S DNA (sigmao appromiately 0). Removal of the drug reverses the transition, covalently closed circular 34-S DNA to covalently closed circular 29-S DNA to covalently closed circular 24-S DNA. The covalently closed circular 24-S mitochondrial DNA is not replicated. Transcription of this DNA is also inhibited as indicated by the fact that no synthesis of the mitochondrial ribosomal RNAs occurs as long as the mitochondrial DNA is in this conformation. The covalently closed circular 29-S mitochondrial DNA is replicated but not transcribed in vivo.

摘要

在培养的人类细胞中，向培养基中添加贝尼尔会改变闭环线粒体DNA的构象，使得34-S线粒体DNA转化为29-S DNA，最终转化为24-S DNA。共价闭合的29-S线粒体DNA的超螺旋密度为σO = -1.5×10^(-2)（每10个碱基对的匝数），因此介于34-S DNA的超螺旋密度（σ0 = -2.8×10^(-2)）和闭环24-S DNA的超螺旋密度（σo约为0）之间。去除药物会使转变逆转，即从共价闭合的环状34-S DNA转变为共价闭合的环状29-S DNA，再转变为共价闭合的环状24-S DNA。共价闭合的环状24-S线粒体DNA不进行复制。这种DNA的转录也受到抑制，这一事实表明，只要线粒体DNA处于这种构象，就不会有线粒体核糖体RNA的合成。共价闭合的环状29-S线粒体DNA在体内进行复制但不转录。