Functional characterization of transport proteins of the calcium-dependent signaling pathway in the regulation of cellulase expression by the fungus Trichoderma reesei

Author(s)

Letícia Harumi Oshiquiri

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2024-05-17

Examining board members

Roberto do Nascimento Silva; Alessandra Monteiro de Paula; Lívia Soares Zaramela

• Advisor: Roberto do Nascimento Silva; Renato Graciano de Paula

Abstract

This study aimed to contribute to the understanding of the role of vacuolar calcium transport proteins in regulating the expression of T. reesei genes that act in the deconstruction of lignocellulosic biomass. To achieve this, we carried out the functional characterization of 4 calcium transport proteins that were previously identified by the group. To this end, we obtained mutant strains with the absence of each of these proteins. Growth assays demonstrated that the mutant strains grow more than the parental strain in the presence of xylose and galactose. This indicates that the proteins under study are involved in sugar metabolism. Furthermore, we did not observe significant differences in growth in the presence of different concentrations of calcium in glucose, showing that vacuolar calcium transport proteins are not involved in resistance to the metal. Through enzymatic activity assays, it was observed that the increase in cellulolytic activity that occurs in the parental strain with the addition of calcium did not occur in the mutant strains. This event was also investigated through the evaluation of cellulase gene expression, where the same change was observed. It is possible that with the absence of calcium transport proteins, calcium is retained within the vacuoles, since 3 mutants evaluated present an absence of the YVC1 calcium channel, responsible for the exit of calcium from the vacuoles. These results show the involvement of the calcium-mediated signaling pathway, especially vacuolar transporters, in the regulation of cellulase expression in T. reesei, enabling the identification of new targets for optimizing the lignocellulosic biomass manipulation process. (AU)

• FAPESP's process: 19/19569-0 - Functional characterization of the calcium-dependent signaling pathway in the regulation of cellulases expression by the fungus Trichoderma reesei
• Grantee: Letícia Harumi Oshiquiri
• Support Opportunities: Scholarships in Brazil - Doctorate