ATP induces a conformational change in lipid-bound cytochrome c.
Resonance energy transfer studies using a pyrene-labeled phospholipid derivative 1-palmitoyl-2-[10-(pyren-1-yl)decanoyl]-sn-glycero-3-phosphoglycerol (donor) and the heme (acceptor) of cytochrome c (cyt c) have indicated that ATP causes changes in the conformation of the lipid-bound protein (Rytömaa, M., Mustonen, P., and Kinnunen, P. K. J. (1992) J. Biol. Chem. 267, 22243-22248). Accordingly, after binding cyt c via its so called C-site to neat phosphatidylglycerol liposomes (mole fraction of PG = 1.0) has commenced, further quenching of donor fluorescence is caused by ATP, saturating at 2 mm nucleotide. ATP-induced conformational changes in liposome-associated cyt c could be directly demonstrated by CD in the Soret band region (380-460 nm). The latter data were further supported by time-resolved spectroscopy using the fluorescent cyt c analog with a Zn(2+)-substituted heme moiety. A high affinity ATP-binding site has been demonstrated in cyt c (Craig, D. B., and Wallace, C. J. A. (1993) Protein Sci. 2, 966-976) that is compromised by replacing the invariant Arg(91) to norleucine. Although no major effects on conformation and function of cyt c were concluded due to the modification, a significantly reduced effect by ATP on the lipid-bound [Nle(91)]cyt c was evident, implying that this modulation is mediated via the Arg(91)-containing binding site.
Tuominen
E K
EK
Helsinki Biophysics and Biomembrane Group, Department of Medical Chemistry, Institute of Biomedicine, P.O. Box B8 (Siltavuorenpenger 10 A), University of Helsinki, FIN-00014 Helsinki, Finland.
Zhu
K
K
Wallace
C J
CJ
Clark-Lewis
I
I
Craig
D B
DB
Rytomaa
M
M
Kinnunen
P K
PK
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001120:Arginine / Q000737:chemistry; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003574:Cytochrome c Group / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006736:Horses; D006863:Hydrogen-Ion Concentration; D050356:Lipid Metabolism; D008081:Liposomes / Q000378:metabolism; D008958:Models, Molecular; D009646:Norleucine / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000737:chemistry
D003574:Cytochrome c Group; D008081:Liposomes; D009646:Norleucine; D000255:Adenosine Triphosphate; D001120:Arginine; D015032:Zinc