Conformational and Structural Changes Induced by Ligand Binding in Yarrowia lipolytica Sterol Carrier Protein-2

BURGARDT, N. I.; FERREYRA, R. G.; CÓRSICO, B.; ERMÁCORA, M. R.; CEOLÍN, M.R.

Montevideo

Congreso; VI International Conference of Biological Physics- ICBP2007, V Southern Cone Biophysics Congress, XXXVI Annual Meeting of the Argentinean Biophysical Society; 2007

International Union of Pure and Applied Physics, International Union for Pure and Applied Biophysics

Yarrowia lipolytica sterol carrier protein-2 (YLSCP-2) binds a broad spectrum of ligands with different physicochemical properties. In previous work, we have observed that p-CoA binding attenuates fluorescence of YLSCP-2 and that the binding of 1,8-ANS induces protein destabilization in the urea-induced unfolding. Now, the effect of ligand binding on the stability of YLSCP-2 was further investigated. The thermal unfolding of YLSCP-2 with and without ligands was monitored by circular dichroism (CD) at 220 nm, and the thermodynamics parameters for the transition were obtained by fitting a two-state model to the experimental data. Below the critical micellar concentration, p-CoA does not affect protein stability and structure. On the other hand, 1,8-ANS produces a significant change of the tertiary structure and destabilizes the protein. The results suggests either that the binding sites or the interaction mode is quite different for the two ligands. Moreover, ANS may have greater affinity for a partially folded than for the native state of YLSCP-2, as observed in other cases.