Abstract
Paracoccidioides brasiliensis infectious process relies on the initial expression of virulence factors that are assumed to be controlled by molecular mechanisms through which the conidia and/or mycelial fragments convert to yeast cells. In order to analyze the profile of the thermally-induced dimorphic gene expression, 48 h C-L transition cultures which had been incubated at 36°C were studied. By this time approximately 50% of the conidial population had already reverted to yeast form cells. At this transition time, an EST-Orestes library was constructed and characterized. As a result, 79 sequences were obtained, of which 39 (49.4%) had not been described previously in other libraries of this fungus and which could represent novel exclusive C-Y transition genes. Two of these sequences are, among others, cholestanol delta-isomerase, and electron transfer flavoprotein-ubiquinoneoxidoreductase (ETF-QO). The other 40/79 (50.6%) sequences were shared with Mycelia (M), Yeast (Y) or Mycelia to yest transition (M-Y) libraries. An important component of this group of sequences is a putative response regulator receiver SKN7, a protein of high importance in stress adaptation and a regulator of virulence in some bacteria and fungi. This is the first report identifying genes expressed during the C-Y transition process, the initial step required to understand the natural history of P. brasiliensis conidia induced infection.
Acknowledgements
This work was supported by Colciencias, Bogotá-Colombia, research grant No. 22130412669, Contract 476-2002; and by Centro para Investigación y Desarrollo – CIDI -of the Universidad Pontificia Bolivariana, Medellín Colombia (Record 7918). Dr Gustavo H. Goldman was supported by FAPESP and CNPq, Brazil. Ana María García C. received support from both the Programa de Apoyo a Doctorados Nacionales (Colciencias, Bogotá-Colombia) and from ACIN – Antioquia (Asociación Colombiana de Infectología – Capítulo de Antioquia).
The authors express their appreciation to Dr Luiz Travassos from the Universidad de São Paulo, São Paulo, Brazil for his contribution during this study.
Conflict of interest: None
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
This paper was first published online on Early Online on 30 June 2009.