Structure prediction and functional analysis of a non-permutated lectin from Dioclea grandiflora

• Published in: Biochimie 2016-12, Vol.131, p.54-67
• Main Authors: de Sousa, Bruno Lopes, Nagano, Celso Shiniti, Simões, Rafael da Conceição, Silva-Filho, José Caetano, Cunha, Rodrigo Maranguape da Silva, Cajazeiras, João Batista, do Nascimento, Kyria Santiago, Cavada, Benildo Sousa
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Binding Sites - genetics; Carbohydrates - chemistry; Computational Biology - methods; Crystallography, X-Ray; Dioclea - genetics; Dioclea - metabolism; Diocleinae; Electrophoresis, Polyacrylamide Gel; Escherichia coli - genetics; Functional analysis; Lectin; Molecular Dynamics Simulation; Plant Lectins - chemistry; Plant Lectins - genetics; Plant Lectins - metabolism; Precursor; Protein Binding; Protein Domains; Protein Precursors - chemistry; Protein Precursors - genetics; Protein Precursors - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Analysis, Protein; Structure prediction; Tandem Mass Spectrometry
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/j.biochi.2016.09.010

Legume lectins have been widely studied and applied for many purposes in the last few decades, but many of their physiological aspects remain elusive. The Diocleinae legume subtribe, which includes intensively explored lectins, such as ConA, presents an unusual and extensive post-translational process which results in minor alterations in protein structure, in turn making its function elusive. Despite previous reports about Diocleinae precursor activity, no structural or functional analyses have ever been carried out to understand the impacts of post-translational processing relative to lectin structure and binding specificity. Here we analyzed the functionality of a non glycosylated, recombinantly expressed lectin precursor from Dioclea grandiflora through inhibition assays, corroborating the experimental data with structural information generated by molecular modeling, docking calculations and molecular dynamics simulations. We demonstrate that Diocleinae precursors are active and share the same carbohydrate specificity as mature lectins. At the same time, however, subtle structural alterations were detected and mostly result in an “incomplete” functionality of the precursor, as consequence of an immature binding site and an unstructured tetramer interface, affecting carbohydrate binding and oligomer formation, respectively. •Structural prediction and computational analysis of a legume lectin precursor.•Functional analysis of a non-glycosylated legume lectin precursor.•Insights about the influence of circular permutation over lectin structure.•Structural comparison between a lectin precursor and its fully processed counterpart.