Dissociation of the Dimer of the Intrinsically Disordered Domain of RNase Y upon Antibody Binding.
Biophys J
; 115(11): 2102-2113, 2018 12 04.
Article
em En
| MEDLINE
| ID: mdl-30447990
ABSTRACT
Although RNase Y acts as the key enzyme initiating messenger RNA decay in Bacillus subtilis and likely in many other Gram-positive bacteria, its three-dimensional structure remains unknown. An antibody belonging to the rare immunoglobulin G (IgG) 2b λx isotype was raised against a 12-residue conserved peptide from the N-terminal noncatalytic domain of B. subtilis RNase Y (BsRNaseY) that is predicted to be intrinsically disordered. Here, we show that this domain can be produced as a stand-alone protein called Nter-BsRNaseY that undergoes conformational changes between monomeric and dimeric forms. Circular dichroism and size exclusion chromatography coupled with multiangle light scattering or with small angle x-ray scattering indicate that the Nter-BsRNaseY dimer displays an elongated form and a high content of α-helices, in agreement with the existence of a central coiled-coil structure appended with flexible ends, and that the monomeric state of Nter-BsRNaseY is favored upon binding the fragment antigen binding (Fab) of the antibody. The dissociation constants of the IgG/BsRNaseY, IgG/Nter-BsRNaseY, and IgG/peptide complexes indicate that the affinity of the IgG for Nter-BsRNaseY is in the nM range and suggest that the peptide is less accessible in BsRNaseY than in Nter-BsRNaseY. The crystal structure of the Fab in complex with the peptide antigen shows that the peptide adopts an elongated U-shaped conformation in which the unique hydrophobic residue of the peptide, Leu6, is completely buried. The peptide/Fab complex may mimic the interaction of a microdomain of the N-terminal domain of BsRNaseY with one of its cellular partners within the degradosome complex. Altogether, our results suggest that BsRNaseY may become accessible for protein interaction upon dissociation of its N-terminal domain into the monomeric form.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Fragmentos de Peptídeos
/
Ribonucleases
/
Bacillus subtilis
/
Fragmentos Fab das Imunoglobulinas
/
Proteínas Intrinsicamente Desordenadas
/
Anticorpos Monoclonais
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Biophys J
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
França