AnÃlise da expressÃo de fatores envolvidos na sÃntese de proteÃnas durante o ciclo de vida de Leishmania sp.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

In eukaryotes, the critical initiation stage of protein synthesis is mostly associated with regulatory mechanisms. Besides the ribosomal subunits, this stage requires the action of a number of translation initiation factors (eIFs). Paramount within those is the eIF4F complex, which is composed by the subunits eIF4A, eIF4E and eIF4G. In Leishmania, translation control is essential to achieve regulation of gene expression, but so far it has been little studied. In this pathogen, multiple homologues to the subunits of the eIF4F complex have been identified and had their expression quantified in the promastigote (Pm) stage of its life cycle. Here we have begun the study of a Leishmania homologue of the ribosomal protein P0, a component of the 60S subunit. Through the cloning of its gene, expression in Escherichia coli and production of specific polyclonal serum, its intracellular levels have been quantified (~6,6x105 molecules/cell) and found to be superior to those observed for the eIF4F homologues. To analyze its expression during the parasite life cycle, the conditions for the growth of representative species of Leishmania and their differentiation into the metacyclic promastigote (MtPm) and amastigote (Am) life stages were first optimized. The detection of proteins whose expression are stage specific (A2- Am; META1 â MtPm) was attempted to validate these growth curves, but only the META1 protein was found, although amastigote cells were observed through the microscope. The expression of P0 was found to be constant within these various life forms. In comparison, the expression of a homologue of the eIF4G protein, LmEIF4G3, also was found to be constant, whilst the LmEIF4G1 homologue was only detected at the Pm and Am stages. Assays with other eIF4F homologues are currently being performed so as to better characterize the processes involved in translation initiation in Leishmania and the control of its cellular differentiation

ASSUNTO(S)

tripanossomatÃdeos ribossomal protein iniciaÃÃo da traduÃÃo ciclo de vida da leishmania genetica translation initiation stage specific expression trypanosomatids expressÃo estÃgio especÃfica proteÃna ribossomal leishmania life cycle

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