Open AccessTertiary Structure and Function of Closed‐Circular Mitochondrial DNA and Its Transcription in vivo
Author(s) -
RASTOGI Anil K.,
ERLINGER Rudolf F. L. S.,
KOCH Jürgen
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb02297.x
Subject(s) - superhelix , mitochondrial dna , circular dna , dna , covalent bond , dna supercoil , transcription (linguistics) , microbiology and biotechnology , heavy strand , hmg box , biology , biophysics , chemistry , biochemistry , dna replication , rna , transcription factor , dna binding protein , gene , genome , transfer rna , linguistics , philosophy , organic chemistry
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 Ó 0 =− 1.5 × 10 −2 (turns/10 base pairs) and consequently is intermediate between the superhelix density of the 34‐S DNA (Ó 0 =− 2.8 × 10 −2 ) and that of the closed circular 24‐S DNA (σ 0 ∼ 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 .