Revisiting Proteus 2.0: Two Decades of Pioneering Lectin Crystallography at BioMol-Lab in Northeast Brazil

This narrative review reports two decades of pioneering X-ray crystallography research on plant lectins at the BioMol-Lab (Northeast, Brazil). Inspired by the shape-shifting Greek god Proteus, our work has consistently highlighted the structural plasticity and functional diversity of these carbohydrate-binding proteins. From modest beginnings, relying heavily on international collaborations, BioMol-Lab established the first protein crystallization laboratory outside of São Paulo, Brazil, becoming a regional and national leader in structural biology. We detail the evolution of our research, from early successes in solving structures of ConA-like lectins and the novel Jacalin-related lectin from Parkia platycephalla, to our current integration of high-throughput crystallography, advanced synchrotron techniques (utilizing Brazil's LNLS and Sirius facilities), and computational methods (Molecular modeling, molecular docking, and molecular dynamics simulations). Key findings include the identification of noncanonical binding sites (e.g., for α-aminobutyric acid and indole-3-acetic acid), the elucidation of pH-dependent oligomerization mechanisms, and attempts to define the structural basis for the diverse biological activities of plant lectins. The combination of structural determination with predictive bioinformatics is also discussed. This review emphasizes the importance of small structural variations in dictating the outcomes of these proteins in various biological activities and showcases the power of combining structural biology with Brazilian biodiversity to generate novel insights into plant lectin biology and biotechnological potential.