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
Lugar:
Salta
Reunión:
Congreso; Latin American Protein Society Meeting, SAB and Workshop CeBEM; 2010
Resumen:
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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.