Caracterização molecular e funcional dos genes ras1 e ras2 do fungo dimórfico e patogênico Paracoccidioides Brasiliensis
AUTOR(ES)
Larissa Fernandes
DATA DE PUBLICAÇÃO
2007
RESUMO
Paracoccidioides brasiliensis is a thermo-dimorphic fungus that causes a human systemic mycosis with high incidence in Latin America. Due to their participation in the control of pathogen morphogenesis, differentiation and virulence the characterization of ras genes in P. brasiliensis was done. It was identified ras1 and ras2 coding for two different proteins with high identity. The ras transcriptional pattern was investigated by RT-PCR during mycelium-to-yeast (M→Y) transition, heat shock at 42C and after internalization of yeast cells by murine macrophages. Both genes were down regulated inside macrophages and ras1, at 42C. In contrast, the ras genes did not show any transcriptional variation during the M→Y transition. The fact that Ras proteins are attached to the membrane via farnesylation prompted the search on Pb gene database for the genes coding the subunits of the prenyltransferases (farnesyltransferase and geranilgeraniltransferase I): ram1, ram2 and cdc43. P. brasiliensis has all genes necessary to the prenylation machinary. Also, a farnesyltransferase inhibitor was used to investigate the importance that process to vegetative growth and dimorphic transition. Farnesylation inhibition interfered with vegetative growth of yeast cells and stimulated germinative tube production even at 37C. During Y→M transition the inhibitor increased filamentation in a dose-dependent manner, indicating that impairement of farnesylation favors the mycelium form of P. brasiliensis. The results suggest that ras genes might have a role in dimorphism, heat shock response and in host-pathogen interaction. A strategy to study the ras1 function in P. brasiliensis via RNA interference was designed. Cassettes with ras1 sense and antisense were constructed for further investigate in detail the possible roles of ras genes in this fungal pathogen
ASSUNTO(S)
paracoccidioides brasiliensis ras biologia molecular
Documentos Relacionados
- Phosphorylation of RAS1 and RAS2 proteins in Saccharomyces cerevisiae.
- Multiple regulatory mechanisms control the expression of the RAS1 and RAS2 genes of Saccharomyces cerevisiae.
- Caracterização molecular das subunidades catalítica e regulatória da calcineurina no fungo patogênico Paracoccidioides brasiliensis.
- A lisozima desempenha um papel duplo contra o fungo dimórfico Paracoccidioides brasiliensis
- Avaliação do efeito do complemento de cão "in vitro" sobre o fungo dimórfico Paracoccidioides brasiliensis