Structural changes and proapoptotic peroxidase activity of cardiolipin-bound mitochondrial cytochrome c

Details

• Personal Author:
  Ahn J ; DeLucia M ; Hoop CL ; Kagan VE ; Kodali R ; Mandal A ; van der Wel PCA
• Description:
  The cellular process of intrinsic apoptosis relies on the peroxidation of mitochondrial lipids as a critical molecular signal. Lipid peroxidation is connected to increases in mitochondrial reactive oxygen species, but there is also a required role for mitochondrial cytochrome c (cyt-c). In apoptotic mitochondria, cyt-c gains a new function as a lipid peroxidase that catalyzes the reactive oxygen species-mediated chemical modification of the mitochondrial lipid cardiolipin (CL). This peroxidase activity is caused by a conformational change in the protein, resulting from interactions between cyt-c and CL. The nature of the conformational change and how it causes this gain-of-function remain uncertain. Via a combination of functional, structural, and biophysical experiments we investigate the structure and peroxidase activity of cyt-c in its membrane-bound state. We reconstituted cyt-c with CL-containing lipid vesicles, and determined the increase in peroxidase activity resulting from membrane binding. We combined these assays of CL-induced proapoptotic activity with structural and dynamic studies of the membrane-bound protein via solid-state NMR and optical spectroscopy. Multidimensional magic angle spinning (MAS) solid-state NMR of uniformly (13)C,(15)N-labeled protein was used to detect site-specific conformational changes in oxidized and reduced horse heart cyt-c bound to CL-containing lipid bilayers. MAS NMR and Fourier transform infrared measurements show that the peripherally membrane-bound cyt-c experiences significant dynamics, but also retains most or all of its secondary structure. Moreover, in two-dimensional and three-dimensional MAS NMR spectra the CL-bound cyt-c displays a spectral resolution, and thus structural homogeneity, that is inconsistent with extensive membrane-induced unfolding. Cyt-c is found to interact primarily with the membrane interface, without significantly disrupting the lipid bilayer. Thus, membrane binding results in cyt-c gaining the increased peroxidase activity that represents its pivotal proapoptotic function, but we do not observe evidence for large-scale unfolding or penetration into the membrane core. [Description provided by NIOSH]
• Subjects:
  Antioxidants Lipids Occupational Health Safety
• Keywords:
  Antioxidation Cell-function Cellular-function Cellular-structures Lipid-peroxidation Proteins
• ISSN:
  0006-3495
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  109
• Issue:
  9
• NIOSHTIC Number:
  nn:20047522
• Citation:
  Biophys J 2015 Nov; 109(9):1873-1884
• Contact Point Address:
  Patrick C.A. van der Wel, Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
• Email:
  pvdwel@pitt.edu
• Federal Fiscal Year:
  2016
• NORA Priority Area:
  Manufacturing
• Performing Organization:
  University of Pittsburgh at Pittsburgh
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Biophysical Journal
• End Date:
  20160630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:ebdebb0efd76e5a310bdc940a39525adb92a17fe91d9a49668b267a62578a413896e403124a871b399995c8000d1ffc5f322b43a0f9e1a8db3b5148c47624b0a
• Download URL:
  https://stacks.cdc.gov/view/cdc/202561/cdc_202561_DS1.pdf
• File Type:
  [PDF - 1.46 MB ]