Stability improvement of the fatty acid binding protein Sm14 from S. mansoni by Cys replacement: structural and functional characterization of a vaccine candidate

Biochim Biophys Acta. 2009 Apr;1794(4):655-62. doi: 10.1016/j.bbapap.2008.12.010. Epub 2008 Dec 25.


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 [[10]. 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Computer Simulation
  • Fatty Acid Transport Proteins / chemistry*
  • Fatty Acid Transport Proteins / genetics
  • Fatty Acid Transport Proteins / immunology*
  • Female
  • Helminth Proteins / chemistry*
  • Helminth Proteins / genetics
  • Helminth Proteins / immunology*
  • Mice
  • Models, Molecular
  • Mutation
  • Protein Folding
  • Protein Multimerization
  • Protein Stability
  • Schistosoma mansoni / chemistry*
  • Schistosoma mansoni / genetics
  • Schistosoma mansoni / growth & development
  • Schistosoma mansoni / immunology
  • Schistosomiasis mansoni / parasitology
  • Schistosomiasis mansoni / prevention & control
  • Vaccines / administration & dosage
  • Vaccines / chemistry


  • Fatty Acid Transport Proteins
  • Helminth Proteins
  • Vaccines
  • SM14 protein, Schistosoma mansoni

Associated data

  • PDB/2POA