Open AccessPreferential Digestion of (A + T)‐Rich Stretches of Yeast Mitochondrial DNA in Isolated Mitochondria
Author(s) -
ZEMAN Leos J.,
LUSENA Charles V.
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.tb02331.x
Subject(s) - mitochondrial dna , micrococcal nuclease , dna , biochemistry , biology , nuclear dna , mitochondrion , microbiology and biotechnology , yeast , isopycnic , incubation , centrifugation , chromatin , gene , nucleosome
Yeast mitochondrial DNA labelled in vitro by incubation of isolated mitochondria with DNA precursors exhibits skewed profiles on isopycnic CsCl gradients. The skew is not due to nuclear DNA nor to single‐stranded mitochondrial DNA in the product labelled in vitro . Simultaneous labelling with [ 3 H]dTTP and [ 14 C]dCTP in vitro indicates a gradient of base composition in the DNA labelled in vitro . Thus, selective degradation of mitochondrial DNA occurs during incubation, converting large molecules having the mean density of mitochondrial DNA into smaller molecules of higher mean density and with higher G:T ratio. Similarly skewed distributions can also be produced by incubation of mitochondrial DNA labelled in vivo with the yeast mitochondrial fraction or with micrococcal endonuclease, an enzyme known to selectively hydrolyse (A + T)‐rich regions of DNA.