Open AccessHuman mitochondrial DNA: analysis of 7S DNA from the origin of replication.
Author(s) -
Wesley M. Brown,
John Shine,
Howard M. Goodman
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.2.735
Subject(s) - mitochondrial dna , restriction enzyme , biology , dna , nucleotide , microbiology and biotechnology , genetics , mtdna control region , restriction fragment , d loop , heavy strand , human mitochondrial genetics , population , endonuclease , dna replication , rna , gene , genotype , transfer rna , demography , sociology , haplotype
Heat-treated samples of human mitochondrial DNA (mtDNA) exhibited a set of three low molecular weight DNA bands in addition to the major mtDNA band when electrophoresed in polyacrylamide gels. These DNA components were seen only after heat treatment or after relaxation of the mtDNA with a restriction endonuclease. The three components were single stranded and had sizes of 550, 585, and 629 nucleotides, close to the size (600 nucleotides) estimated from contour length measurements for the 7S DNA from the D loop of human mtDNA. Hybridization of the components with restriction endonuclease fragments of known position in the mtDNA confirmed this identification. Digestion of each 7S DNA component with the restriction endonuclease Hae III produced three fragments, two of which were identical in size among the components and the third of which varied. This third fragment, shown to be from the 5' end of each component, differed in length by approximately 35 nucleotides among the components. These results suggest that human 7S mtDNA synthesis is terminated at a distinct position and that it is either initiated at one of three possible sites in the same mtDNA or that the mtDNA population consists of three subpopulations, each differing from the others by the presence or absence of a nucleotide sequence immediately adjacent to the origin of replication.