Tertiary structural changes of the alpha-hemolysin from Staphylococcus aureus on association with liposome membranes
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Data
1998-03-01
Autores
Bortoleto, R. K.
de Oliveira, AHC
Ruller, R.
Arni, R. K.
Ward, R. J.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Academic Press Inc.
Resumo
The interaction of alpha-hemolysin (also called alpha-toxin) from Staphylococcus aureus with mixed egg-yolk phosphatidylcholine/cholesterol liposomes has been investigated using the intrinsic tryptophan fluorescence emission (ITFE) signal. The ITFE intensity of alpha-hemolysin, which was obtained using a novel purification protocol, showed a triphasic increase on incubation with liposomes at low protein/lipid ratios. The first, rapid phase results in an increase in ITFE of 10%, which reflects rapid conformation changes in the alpha-hemolysin on association with the liposome membrane, the second phase of the ITFE increase is associated with a red shift from 334 to 339 nm in the maximum emission wavelength, suggesting the transition to a partially unfolded intermediate in the oligomerization process. The third phase of the ITFE intensity change demonstrates a temporal correlation with the appearance of SDS-stable oligomers. The results demonstrate the feasibility of identification of intermediate protein conformations in complex membrane-associated processes by manipulation of the liposomal membrane composition. (C) 1998 Academic Press.
Descrição
Palavras-chave
alpha-hemolysin, alpha-toxin, Staphylococcus aureus, pore-forming, liposome membrane, unfolded intermediate
Como citar
Archives of Biochemistry and Biophysics. San Diego: Academic Press Inc., v. 351, n. 1, p. 47-52, 1998.