IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Recognition mechanism of an intrinsically disordered antigen by a monoclonal antibody
Autor/es:
FASSOLARI, M; CERUTTI, ML; CHEMES, L; SMAL, C; HEER, A; DE PRAT GAY, G.
Lugar:
Salta
Reunión:
Congreso; XXXIX Annual Meeting of the Argentinean Biophysical Society. 3rd Latin American Protein Society Meeting; 2010
Institución organizadora:
Argentinean Biophysical Society and Latin American Protein Society
Resumen:
Persistent infections by high-risk human
papillomaviruses (HPV) are the main etiologic factors for cervical cancer. The major cell transforming activity of HPVs
is the E7 oncoprotein. HPV16 E7 is
an extended dimer with a conserved N-terminal intrinsically disordered domain
and a globular C-terminal domain. E7 represents an interesting model to
investigate the recognition mechanism of intrinsically disordered antigens by
antibodies. Here, we present a characterization
of the interaction between E7 and the specific M1 monoclonal antibody. Spectroscopic
solution binding experiments indicate high
binding affinity. Fragmentation analysis of E7 shows that M1
recognizes an epitope comprising amino acids 36-48. Kinetic
studies between M1 and E736-48 suggest two phases in complex
formation: a fast protein-concentration bimolecular association phase (kon 1.108 M-1
seg-1) and a slow protein concentration independent phase (kobs
4.10-3 S-1). Circular dichroism experiments indicated
conformational changes induced by the binding corresponding to the slow phase
observed in kinetic experiments. The equilibrium dissociation
constant of M1 for the E736-48 peptide is 6-fold higher
than that measured for full length E7.
This result suggests that the highest affinity recognition by the M1
requires entire E7. This study shows the
recognition mechanism of a unique epitope, located between the N-terminal and
the C-terminal regions of E7, by a monoclonal antibody.