title: Moniliophthora perniciosa necrosis- and ethylene-inducing protein 2 (MpNep2) as a metastable dimer in solution: structural and functional implications.
abstract: Understanding how Nep-like proteins (NLPs) behave during the cell cycle and disease progression of plant pathogenic oomycetes, fungi and bacteria is crucial in light of compelling evidence that these proteins play a role in Witches` Broom Disease (WBD) of Theobroma cacao, one of the most important phytopathological problems to afflict the Southern Hemisphere. The crystal structure of MpNep2, a member of the NLP family and the causal agent of WBD, revealed the key elements for its activity. This protein has the ability to refold after heating and was believed to act as a monomer in solution, in contrast to the related homologs MpNep1 and NPP from the oomyceteous fungus Phytophthora parasitica. Here, we identify and characterize a metastable MpNep2 dimer upon over-expression in Escherichia coli using different biochemical and structural approaches. We found using ultra-fast liquid chromatography that the MpNep2 dimer can be dissociated by heating but not by dilution, oxidation or high ionic strength. Small-angle X-ray scattering revealed a possible tail-to-tail interaction between monomers, and nuclear magnetic resonance measurements identified perturbed residues involved in the putative interface of interaction. We also explored the ability of the MpNep2 monomer to refold after heating or chemical denaturation. We observed that MpNep2 has a low stability and cooperative fold that could be an explanation for its structure and activity recovery after stress. These results can provide new insights into the mechanism for MpNep2's action in dicot plants during the progression of WBD and may open new avenues for the involvement of NLP- oligomeric species in phytopathological disorders.
authors.affiliation: Programa de Biologia Estrutural, Instituto de Bioquímica Médica, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Guilherme A P
authors.initials: GA
authors.lastname: de Oliveira
authors.forename: Elen G
authors.initials: EG
authors.lastname: Pereira
authors.forename: Cristiano V
authors.initials: CV
authors.lastname: Dias
authors.forename: Theo L F
authors.initials: TL
authors.lastname: Souza
authors.forename: Giulia D S
authors.initials: GD
authors.lastname: Ferretti
authors.forename: Yraima
authors.initials: Y
authors.lastname: Cordeiro
authors.forename: Luciana R
authors.initials: LR
authors.lastname: Camillo
authors.forename: Júlio
authors.initials: J
authors.lastname: Cascardo
authors.forename: Fabio C
authors.initials: FC
authors.lastname: Almeida
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Valente
authors.forename: Jerson L
authors.initials: JL
authors.lastname: Silva
mesh_terms: D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012542:Scattering, Radiation; D012996:Solutions; D013816:Thermodynamics
chemical_list: D005656:Fungal Proteins; D011994:Recombinant Proteins; D012996:Solutions