Open AccessBilayer‐penetrating properties enable apocytochrome c to follow a special import pathway into mitochondria
Author(s) -
JORDI Wilco,
HERGERSBERG Christoph,
KRUIJFF Ben
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb16703.x
Subject(s) - mitochondrion , organelle , biochemistry , lipid bilayer , cytochrome c oxidase , liposome , intermembrane space , bilayer , cytochrome c , lipid bilayer fusion , in vitro , biology , chemistry , microbiology and biotechnology , membrane , bacterial outer membrane , escherichia coli , gene
In this study, we have investigated the protein/lipid interactions of two mitochondrial precursor proteins, apocytochrome c and pCOX IV‐DHFR, which exhibit mitochondrial import pathways with different characteristics. In‐vitro ‐synthesized apocytochrome c was found to bind efficiently and specifically to liposomes composed of negatively charged phospholipids and showed a (at least partial) translocation across a lipid bilayer, as reported previously for the chemically prepared precursor protein [Rietveld, A. & de Kruijff, B. (1984) J. Biol. Chem. 259 , 6704–6707; Dumont, M. E. & Richards, F. M. (1984) J. Biol. Chem. 259 , 4147–4156]. Negatively charged liposomes were shown to efficiently compete with mitochondria for import of in‐vitro ‐synthesized apocytochrome c into the organelle, suggesting an important role for negatively charged phospholipids in the initial binding of apocytochrome c to mitochondria. In contrast, the purified and in‐vitro ‐synthesized precursor fusion protein pCOX IV‐DHFR, consisting of the presequence of yeast cytochrome oxidase subunit IV fused to mouse dihydrofolate reductase was unable to translocate across a pure lipid bilayer. The data indicate that the ability of apocytochrome c to spontaneously translocate across the bilayer is not shared by all mitochondrial precursor proteins. The implications of the special protein/lipid interaction of apocytochrome c for import into mitochondria will be discussed.