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Title: Effects of transmembrane potential and pH gradient on the cytochrome c-promoted fusion of mitochondrial mimetic membranes
Authors: Kawai, Cintia
Pessoto, Felipe S. [UNIFESP]
Graves, Catharine V.
Carmona-Ribeiro, Ana Maria
Nantes, Iseli L.
Universidade Federal do ABC (UFABC)
Universidade Federal de São Paulo (UNIFESP)
Universidade de São Paulo (USP)
Keywords: Cytochrome c
Site L
Membrane potential
PC/PE/CL liposome
Vesicle fusion
Issue Date: 1-Aug-2013
Publisher: Springer
Citation: Journal of Bioenergetics and Biomembranes. New York: Springer/plenum Publishers, v. 45, n. 4, p. 421-430, 2013.
Abstract: The present study investigated the effects of Delta I and Delta pH (pH gradient) on the interaction of cytochrome c with a mitochondrial mimetic membrane composed of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cardiolipin (CL) leading to vesicle fusion. Delta pH generated by lowered bulk pH (pH(out)) of PCPECL liposomes, with an internal pH (pH(in)) of 8.0, favored vesicle fusion with a titration sigmoidal profile (pK (a) similar to 6.9). Conversely, Delta pH generated by enhanced pH(in) of PCPECL at a pH(out) of 6.0 favored the fusion of vesicles with a linear profile. We did not observe a significant amount of liposome fusion when Delta pH was generated by lowered pH(in) at a pH(out) of 8.0. At bulk acidic pH, Delta I generated by Na+ gradient also favored cyt c-promoted vesicle fusion. At acidic and alkaline pH(out), the presence of Delta pH and Delta I did not affect cytochrome c binding affinity measured by pyrene quenching. Therefore, cytochrome c-mediated PC/PE/CL vesicle fusion is dependent of ionization of the protein site L (acidic pH) and the presence of transmembrane potential. the effect of transmembrane potential is probably related to the generation of defects on the lipid bilayer. These results are consistent with previous reports showing that cytochrome c release prior to the dissipation of the Delta I-M blocks inner mitochondrial membrane fusion during apoptosis.
ISSN: 0145-479X
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Appears in Collections:Em verificação - Geral

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