Effects of Fe(III) binding to the nucleotide-independent site of F1-ATPase: enzyme thermostability and response to activating anions.
Mitochondrial F1-ATPase was induced in different conformations by binding of specific ligands, such as nucleotides. Then, Fourier transform infrared spectroscopy (FT-IR) and kinetic analyses were run to evaluate the structural and functional effects of Fe(III) binding to the nucleotide-independent site. Binding of one equivalent of Fe(III) induced a localised stabilising effect on the F1-ATPase structure destabilised by a high concentration of NaCl, through rearrangements of the ionic network essential for the maintenance of enzyme tertiary and/or quaternary structure. Concomitantly, a lower response of ATPase activity to activating anions was observed. Both FT-IR and kinetic data were in accordance with the hypothesis of the Fe(III) site location near one of the catalytic sites, i.e. at the alpha/beta subunit interface.
Contessi
S
S
Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, Italy. scontessi@makek.dstb.uniud.it
Tanfani
F
F
Scirè
A
A
Mavelli
I
I
Lippe
G
G
D000838:Anions; D001665:Binding Sites; D004789:Enzyme Activation; D004795:Enzyme Stability; D005290:Ferric Compounds / Q000378:metabolism*; D006358:Hot Temperature; D007700:Kinetics; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared
D000838:Anions; D005290:Ferric Compounds; D006180:Proton-Translocating ATPases