Prediction of the Three-Dimensional Structure of Phosphate-6-mannose PMI Present in the Cell Membrane of Xanthomonas citri subsp. citri of Interest for the Citrus Canker Control

Abstract

Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (XAC) is one of the most important diseases in citrus, presenting a significant impact on the Brazilian economy. A promising target enzyme for such disease control is phosphomannose isomerase (PMI). Phosphomannose isomerase is an enzyme that catalyses the interconversion of fructose-6-phosphate (F6P) and mannose-6-phosphate (M6P) and allows the synthesis of GDP-mannose in eukaryotic organisms. In Xanthomonas sp., phosphomannose isomerase is related to the production of xanthan gum, which is a defense mechanism of bacteria to prevent dehydration in harmful environments. Due to the lack of a resolved protein structure, a PMI model was created using the protein homology modeling method and, after protein selection by a BLASTp algorithm and subsequent alignment using ClustalOmega, the model was built using the MODELLER Software. The model was analysed and validated using the WhatIf, ProCheck, Errat, Prove and Verify-3D softwares. The Xanthomonas PMI model proved reliable through the validation and evaluation tests.