IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Oligomerization mechanism of the HPV 16 oncoprotein E7
Autor/es:
C. SMAL; WETZLER DE; ALONSO LEONARDO G.; DE PRAT-GAY GONZALO
Lugar:
Salta
Reunión:
Congreso; XXXIX Annual Meeting of the Argentinean Biophysical Society (SAB 2010); 2010
Resumen:
@font-face {
font-family: "Times New Roman";
}p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 10pt; font-family: "Times New Roman"; }p.MsoBodyTextIndent, li.MsoBodyTextIndent, div.MsoBodyTextIndent { margin: 0cm 0cm 0.0001pt; text-align: justify; text-indent: 14.2pt; font-size: 10pt; font-family: "Times New Roman"; }table.MsoNormalTable { font-size: 10pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; }
The oncoprotein E7 is the major transforming activity in human
papillomaviruses, a causal agent for cervical cancer. More than 40 specific
cellular targets were described for this protein that represents a prototypical
oncoprotein among small DNA tumor viruses. The HPV16 E7 oncoprotein is an
extended dimer, with a stable and cooperative fold, but it displays properties of
intrinsically disorder proteins. The protein can form spherical oligomers with
amyloid-like properties that display chaperone activity. It was previously shown
that oligomers assemble through an ordered process. The oligomers assemble can
be started in vitro by
chelating the structural Zn by EDTA 1,2.
In this work we characterize the kinetic mechanism of oligomers assembly
using different experimental techniques such as circular dichroism and
fluorescence spectroscopy, dynamic light scattering measurements and binding to
specific dyes that report different conformational and structural events. We
could observe three phases in the oligomerization process: a slow lag phase, a
rapid elongation step and a final steady state. A two state process with an
initial monomeric specie and a final homogeneous spherical oligomer without
populated intermediaries was found.
Using a kinetic model
proposed by Zlotnick et al.3
for spherical oligomeric assemblies we propose a simple mechanism where the
formation of E7 monomer species after chelating Zn corresponds to lag phase
observed, followed by the elongation phase where monomeric E7 species are added
one by one to form the final state.