Characterization and comparative functional analysis in yeast of a Schistosoma mansoni Rho1 GTPase gene

Túlio Marcos Santos, Carlos Renato Machado, Glória Regina Franco, Sérgio Danilo Junho Pena

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13 Scopus citations

Abstract

Low-molecular weight GTP-binding proteins (LMWGPs) of the Ras superfamily are believed to play a role in Schistosoma mansoni female development and egg production. Here we describe the characterization of a novel S. mansoni gene (SMRHO1), highly homologous to Rho-type LMWGPs from several other organisms and encoding a polypeptide with 193 amino acids and an estimated molecular mass of 21.8 kDa. SMRHO1 complemented a Saccharomyces cerevisiae rho1 null mutant strain even in restrictive temperature and calcium concentration, in contrast with the human RHOA GTPase that was not able to provide complementation in such conditions. Comparison of the amino acid sequence of the α3-helix loop7 regions of the two proteins allowed the identification of the proline 96 and threonine 100 amino acid residues of human RHOA as the most probable determinants of the complementation differences. We generated SMRHO1 mutants (smrho1E97P, smrho1L101T and smrho1E97P, L101T) by site directed mutagenesis and reproduced the conditional lethality phenotype at high temperature, providing strong evidence that the related amino acid positions (Gln101 and Ile105) in the Rho1 GTPase are indeed important for regulation of the cell wall synthesis performed by this protein in yeast. The observation that specific amino acid positions seem to be important for the different functions performed by the Rho GTPases leads to the idea that SMRHO1 might be a useful target in the development of new anti-schistosomiasis drugs, although it does share high sequence homology with the human RhoA GTPase.

Original languageEnglish
Pages (from-to)103-112
Number of pages10
JournalMolecular and Biochemical Parasitology
Volume125
Issue number1-2
DOIs
StatePublished - 2002
Externally publishedYes

Keywords

  • Complementation
  • Rho GTPase
  • Schistosoma mansoni
  • Site directed mutagenesis
  • Yeast

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