Development of methods for obtaining a recombinant pectin methyl esterase from symbiotic fungus of leaf cutting ant, Leucoagaricus gongylophorus

• Grant number: 12/20020-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): January 01, 2013
• Effective date (End): June 30, 2014
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Dulce Helena Ferreira de Souza
• Grantee: Caio Almeida Batista de Oliveira
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The process of symbiosis between ants of the genus Atta and Acromirmex and fungus L. gongylophorus has been the subject of many studies. Biochemical aspects of the symbiosis between L. gongylophorus and Atta sexdens (lemon ants) have been studied and it has indicated that the interaction is achieved by supplying the ants with fungal enzymes including digestive enzymes such as pectinases. Pectin methylesterases, PMEs, are enzymes that belong to the family of 8-carbohydrate esterases and catalyze the removal reaction of successive units of pectin's methanol, converting it into pectate (not-esterified pectin). PME's are found in plants, bacteria, and fungi, being associated to symbiotic microorganisms during their interaction with plants. The Natural Products group, from the Chemistry Department of UFSCar, has developed, in collaboration with researchers from CEIS - Centre for the Study of Social Insects, Institute of Biosciences, UNESP, Rio Claro campus -, studies to control ants. In this context, the Laboratory of Functional and Structural Biochemistry of UFSCar, coordinated by Professor Dulce Helena Ferreira de Souza, has been devoted to studies of recombinant and native enzymes of the fungus L. gongylophorus, with the goal of searching for specific inhibitors that can act as prototypes of new and more specific insecticides. Recently, studies with the fungus L. gongylophorus showed a protein expression of molecular mass of about 37,500 Da, which has been classified, by sequence identity, such as a pectin methyl esterase. Despite the sequence has been deposited, this protein has never been purified and characterized. Thus, in order to contribute to a better understanding of the digestive enzymes of symbiotic fungus of leaf-cutting ants and, more specifically, about the mechanism of action of pectin methylesterases, it is proposed in this project the obtainment of recombinant PME's from L. gongylophorus, which will enable, in the future, the structural study of the enzyme. The student Caio Oliveira is an apprentice in the Laboratory since January 2012, and he is quite competent and dedicated, and the development of the project will be an important differential in his Academic History. (AU)