The following information was submitted:
Transactions: WSEAS TRANSACTIONS ON BIOLOGY AND BIOMEDICINE
Transactions ID Number: 42-292
Full Name: Abraham H. Parola
Position: Professor
Age: ON
Sex: Male
Address: Ben-Gurion University of the Negev P.O. Box 635, Beer-Sheva, 84105
Country: ISRAEL
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E-mail address: aparola@bgu.ac.il
Other E-mails: nathan@bgu.ac.il
Title of the Paper: Bax∆C Induces Increased Membrane Lipid Order in Isolated Rat Liver Mitochondria
Authors as they appear in the Paper: Natalia Tsesin, Elai Davicioni, Rivka Cohen-Luria, Ilana Nathan, Abraham H. Parola
Email addresses of all the authors: nataliat@bgu.ac.il,davicion@gmail.com,riky@bgu.ac.il,nathan@bgu.ac.il,aparola@bgu.ac.il
Number of paper pages: 14
Abstract: The interaction of the pro-apoptotic Bax∆C with the excimer-forming lipid, 12-(pyrene-1-yl)-dodecanoic acid (PDA) labeled isolated rat liver mitochondria, caused a decrease in PDA excimer-to-monomer fluorescence emission ratio (E/M). This suggested that BaxΔC caused mitochondrial membrane lipid reorganization. These changes were dependent on the Bax∆C protein-to-mitochondrial lipid ratio. The changes in the fluorescence emission spectra were not attributed to overall changes in the bulk properties of the mitochondrial suspensions or to fluorescence resonance energy transfer between the heme group of cytochrome c and pyrene. These data suggested that BaxΔC increases mitochondrial membrane "microviscosity". Fluorescence anisotropy studies with DPH and TMA-DPH labeled mitochondria independently show reduced rotational dynamics, further supporting this presumed increased membrane "microviscosity". The lifetimes of all probes did not change upon Ba!
xΔC interaction with the mitochondrial membrane, verifying the changes in the dynamics of the probe mobility in the membrane. Another pro-apoptotic protein tBid, a more potent inducer of cytochrome c release, also caused an increase in DPH anisotropy, yet to a lesser extent as compare with equal concentration of BaxΔC. The observed increase in DPH anisotropy caused by BaxΔC-membrane interaction was inhibited by the anti-apoptotic protein Bcl-2∆TM. The effects of BaxΔC on the mitochondrial membranes were correlated to cytochrome c release. These findings reflect BaxΔC interaction with the mitochondrial membrane, where the binding of Bax∆C lowers probe mobility and induces major reorganization of mitochondria membrane lipids, possibly a phase transition associated with non-lamellar bilayer structures.
Keywords: apoptosis, tBid, Bcl-2∆TM, cytochrome c, pyrene excimers, fluorescence anisotropy & lifetime, lipid probes, "microviscosity", lipid pores
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