Phosphatidylcholine and phosphatidylethanolamine enhance the activity of the mammalian mitochondrial endonuclease in vitro

W. A. Parks, C. L. Couper, R. L. Low*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The purified endonuclease of bovine heart mitochondria extensively degrades a variety of DNA templates in vitro but shows a remarkably strong preference to nick within one specific evolutionarily conserved sequence block of 12 consecutive guanine residues which resides just upstream from the heavy strand origin of mitochondrial DNA replication (Low, R.L., Cummings, O.W., and King, T.C. (1987) J. Biol. Chem. 262, 16164-16170). If the enzyme serves to provide an important nicking function at this site in vivo, then mitochondrial factors likely exist which further enhance the enzyme's recognition of this locus and prevent cleavage at other less favored sites. In this study, we report that specific membrane phospholipids appear to exert such effects in vitro. In standard endonuclease assays, low levels of phosphatidylcholine or phosphatidylethanolamine (0.5 mM) stimulate the purified enzyme activity 10-20-fold. However, at moderate levels (20-40 mM), these phospholipids largely inhibit widespread degradation of duplex DNA while still allowing site-specific nicking at the conserved guanine target in the mitochondrial genome. These findings suggest that an interaction of the endonuclease with major lipid components of the inner membrane could be an important determinant of the enzyme's specificity for mitochondrial DNA.

Original languageEnglish (US)
Pages (from-to)3436-3439
Number of pages4
JournalJournal of Biological Chemistry
Volume265
Issue number6
StatePublished - 1990

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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