Functional characterization of HsfA transcription factor and study of the thermotolerance, lipid composition and cell wall integrity in Aspergillus fumigatus

• Grant number: 17/13363-5
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: October 01, 2017
• End date: February 28, 2022
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal Investigator: Iran Malavazi
• Grantee: João Henrique Tadini Marilhano Fabri
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated scholarship(s): 18/22755-7 - Lipidomic-focused mass spectrometry of Aspergillus fumigatus mutant strains aiming to understand the relationship between thermotolerance, cell wall integrity and cell membrane lipid composition, BE.EP.DD

Abstract

The filamentous and saprophytic fungus Aspergillus fumigatus is the main causative pathogen of invasive pulmonary aspergillosis (API), a disease that has a high degree of mortality in immunocompromised individuals. Thermotolerance is one of the key virulence determinants of this fungus, being a prerequisite for the establishment of infection and maintenance of the pathogen inside the host. In Saccharomyces cerevisiae, the transcription factor Hsf1 is responsible for the transcription of several heat shock proteins, such as Hsp90, Hsp70, Hsp60 and Hsp40 chaperones, which are part of the cellular program for heat adaptation. In response to temperature shock, fungal organisms trigger different adaptive responses such as that governing the cell membrane homeostasis towards distinct composition and fluidity. In addition, there is an interplay between heat shock response genes and the maintenance of the cell wall integrity in yeast and other fungal pathogens, such as Candida albicans. For this reason, this study intends to expand the research of heat shock response in A. fumigatus by investigating in detail the regulatory network governed by HsfAHSF1 and to uncover a potential role of this protein in the cell wall integrity and membrane lipid composition. In this project we will construct a conditional mutant for hsfA, considering the apparent essentiality of the hsfA gene we demonstrated previously. This mutant will be used in phenotypic, microscopic and lipidomic analysis to the study of cell membrane lipid composition during thermal and cell wall stress. ChIP-qPCR assays will be used to identify HsfA transcriptional targets upon heat shock and cell wall stress. To better address this question, we will also construct and characterize the sdeA (the yeast OLE1 desaturase homologue) strain, in order to understand the importance of the SdeA enzyme to the cell membrane and its relation with the thermotolerance. This project will complement previous studies in our laboratory on thermotolerance and cell wall integrity and will also provide new data that could be applied to other pathogenic fungi or relevant filamentous fungi. (AU)