RESUMO

This paper reports the EhGEF1-EhRacG and EhGEF1-EhRho1 molecular complexes from Entamoeba histolytica. The not conserved amino acids Gln201,Tyr299, Gln302, Lys312, Asn313, Phe314 and Ile324 were localized, by means of an in silico computational analysis, at the interface of the exposed face from the DH domain of EhGEF1, which are important to establish the contact with its target GTPases EhRacG and EhRho1. Functional studies of nucleotide exchange of Phe314Ala mutant showed a decrement of 80% on EhRacG GTPase; in contrast the Ile324Ala mutant exhibited a reduction of 77%, specifically on EhRho1; meanwhile the Gln302Ala mutant showed a reduction of approximately 50% on the exchange activity for both GTPases. Moreover, the functional studies of the protein EhGEF1 mutants in the conserved residues Thr194Ala, Asn366Ala and Glu367Ala indicated that contrary to what has been reported for other systems, the mutation of these residues did not alter considerably its catalytic activity.

Assuntos

Canais de Cloreto/química , Canais de Cloreto/genética , Entamoeba histolytica/fisiologia , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Canais de Cloreto/metabolismo , Análise Mutacional de DNA , Entamoeba histolytica/genética , Proteínas de Ligação ao GTP/metabolismo , Guanosina Trifosfato/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Ligação Proteica , Mapeamento de Interação de Proteínas , Estrutura Quaternária de Proteína , Proteínas de Protozoários/metabolismo