Stability improvement of the fatty acid binding protein Sm14 from S. mansoni by Cys replacement: Structural and functional characterization of a vaccine candidate.Ramos, C.R., Spisni, A., Oyama, S., Sforca, M.L., Ramos, H.R., Vilar, M.M., Alves, A.C., Figueredo, R.C., Tendler, M., Zanchin, N.I., Pertinhez, T.A., Ho, P.L.
(2009) Biochim.Biophys.Acta 1794: 655-662
- PubMed: 19150418
- DOI: 10.1016/j.bbapap.2008.12.010
- PubMed Abstract:
The Schistosoma mansoni fatty acid binding protein (FABP), Sm14, is a vaccine candidate against, S. mansoni and F. hepatica. Previously, we demonstrated the importance of a correct fold to achieve protection in immunized animals after cercariae chall ...
The Schistosoma mansoni fatty acid binding protein (FABP), Sm14, is a vaccine candidate against, S. mansoni and F. hepatica. Previously, we demonstrated the importance of a correct fold to achieve protection in immunized animals after cercariae challenge [. C.R.R. Ramos, R.C.R. Figueredo, T.A. Pertinhez, M.M. Vilar, A.L.T.O. Nascimento, M. Tendler, I. Raw, A. Spisni, P.L. Ho, Gene structure and M20T polymorphism of the Schistosoma mansoni Sm14 fatty acid-binding protein: structural, functional and immunoprotection analysis. J. Biol. Chem. 278 (2003) 12745-12751.]. Here we show that the reduction of vaccine efficacy over time is due to protein dimerization and subsequent aggregation. We produced the mutants Sm14-M20(C62S) and Sm14-M20(C62V) that, as expected, did not dimerize in SDS-PAGE. Molecular dynamics calculations and unfolding experiments highlighted a higher structural stability of these mutants with respect to the wild-type. In addition, we found that the mutated proteins, after thermal denaturation, refolded to their active native molecular architecture as proved by the recovery of the fatty acid binding ability. Sm14-M20(C62V) turned out to be the more stable form over time, providing the basis to determine the first 3D solution structure of a Sm14 protein in its apo-form. Overall, Sm14-M20(C62V) possesses an improved structural stability over time, an essential feature to preserve its immunization capability and, in experimentally immunized animals, it exhibits a protection effect against S. mansoni cercariae infections comparable to the one obtained with the wild-type protein. These facts indicate this protein as a good lead molecule for large-scale production and for developing an effective Sm14 based anti-helminthes vaccine.
Biotechnology Center, Butantan Institute, Av. Vital Brasil 1500, 05503-900, São Paulo, SP, Brazil.