Biochemical characterization of candidate tricin glycosyltransferases in the model grass Setaria viridis

• Grant number: 24/19632-1
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: March 28, 2025
• End date: July 31, 2025
• Field of knowledge: Biological Sciences - Botany - Pant Physiology
• Principal Investigator: Igor Cesarino
• Grantee: Arthur de Barros Rates
• Supervisor: Wilfried Schwab
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Technical University of Munich, Weihenstephan (TUM), Germany
• Associated to the scholarship: 22/12496-0 - Functional characterization of SvUGTs potentially involved in tricin glycosylation in Setaria viridis, BP.DR

Abstract

The phenylpropanoid metabolism is the source of a vast array of specialized metabolites, including lignin, a phenolic polymer crucial for structural support and protection against stresses. Because of its recalcitrant nature, lignin is considered an obstacle to biomass processing into downstream products. Recently, the flavone tricin was identified as an authentic lignin monomer, present mainly in grasses. However, little is known about tricin metabolism. Previously, we hypothesized that UDP glycosyltransferases (UGTs) may play a role in controlling tricin incorporation into the lignin polymer. Thus, the aim of my original project (Processo Fapesp n° 2022/12496-0) is to identify and characterize UGTs involved in the glycosylation of tricin in the model grass Setaria viridis. Three candidate genes were previously selected using in silico and transcriptomic analyses and their corresponding recombinant proteins were successfully produced in E. coli. The aim of this BEPE project is to biochemically characterize these enzymes, determining their activity and kinetic parameters using different flavonoids as substrates, including tricin. These analyses will be performed using LC-MS in the lab of Dr. Wilfried Schwab (Technical University of Munich, Germany), an expert in plant UGTs. The PhD candidate will spend 5 months abroad to (i) express and purify the proteins and (ii) perform in vitro assays to determine kinetics data. These data will be essential to determine the best SvUGT candidate to be overexpressed in S. viridis to assess whether glycosylation plays a role in controlling tricin incorporation into lignin in planta.