RESUMEN
Royal jelly (RJ) triggers the development of female honeybee larvae into queens. This effect has been attributed to the presence of major royal jelly protein 1 (MRJP1) in RJ. MRJP1 isolated from royal jelly is tightly associated with apisimin, a 54-residue α-helical peptide that promotes the noncovalent assembly of MRJP1 into multimers. No high-resolution structural data are available for these complexes, and their binding stoichiometry remains uncertain. We examined MRJP1/apisimin using a range of biophysical techniques. We also investigated the behavior of deglycosylated samples, as well as samples with reduced apisimin content. Our mass spectrometry (MS) data demonstrate that the native complexes predominantly exist in a (MRJP14 apisimin4) stoichiometry. Hydrogen/deuterium exchange MS reveals that MRJP1 within these complexes is extensively disordered in the range of residues 20-265. Marginally stable secondary structure (likely antiparallel ß-sheet) exists around residues 266-432. These weakly structured regions interchange with conformers that are extensively unfolded, giving rise to bimodal (EX1) isotope distributions. We propose that the native complexes have a "dimer of dimers" quaternary structure in which MRJP1 chains are bridged by apisimin. Specifically, our data suggest that apisimin acts as a linker that forms hydrophobic contacts involving the MRJP1 segment 316VLFFGLV322. Deglycosylation produces large soluble aggregates, highlighting the role of glycans as aggregation inhibitors. Samples with reduced apisimin content form dimeric complexes with a (MRJP12 apisimin1) stoichiometry. The information uncovered in this work will help pave the way toward a better understanding of the unique physiological role played by MRJP1 during queen differentiation.
Asunto(s)
Ácidos Grasos/química , Glicoproteínas/química , Proteínas de Insectos/química , Proteínas Intrínsecamente Desordenadas/química , Chaperonas Moleculares/química , Polisacáridos/química , Secuencia de Aminoácidos , Animales , Abejas/crecimiento & desarrollo , Abejas/metabolismo , Medición de Intercambio de Deuterio , Ácidos Grasos/fisiología , Expresión Génica , Glicoproteínas/genética , Glicoproteínas/metabolismo , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Proteínas Intrínsecamente Desordenadas/genética , Proteínas Intrínsecamente Desordenadas/metabolismo , Larva/crecimiento & desarrollo , Larva/metabolismo , Espectrometría de Masas , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Péptidos/química , Péptidos/genética , Péptidos/metabolismo , Polisacáridos/metabolismo , Multimerización de ProteínaRESUMEN
The herbal extract of Schizolobium parahyba leaves is used commonly in the Brazil central region to treat snakebites. This study evaluates the acute toxicological effects of Schizolobium parahyba aqueous extract in mice 24 h after intraperitoneal administration. Acute toxicity was evaluated using biochemical, hematological and histopathological assays. Alterations in the levels of transaminases, bilirubin, albumin and prothrombrin time were observed, and these are likely to occur due to hepatic injury, which was confirmed by light microscopy. Liver histopathological analysis revealed the presence of lymph plasmocitary inflammatory infiltrate, but no other histopathological alterations were observed in any of the other organs analysed. The data confirm the low toxicity of the extract of Schizolobium parahyba and provide a model for the selection of a dose that does not cause injuries in the organism.