131
Modeling of Biomolecular Systems Interactions, Dynamics, and Allostery Poster Session II
78-POS
Board 31
Study of the Interaction of the Extracellular Domain in the ErbB2-ErbB2homodimer and
ErbB2-Trastuzumab by Hydrodynamic Properties and Computational Models
Javier Ramos
1
, Juan Francisco Vega
1
, Victor L. Cruz
1
, Ping Hu
2
, Javier Cortes
3
, Javier
Martinez-Salazar
1
.
1
Instituto de Estructura de la Materia, CSIC, Madrid, Spain,
2
Sino Biological, Inc, Beijing,
China,
3
Vall D'Hebron University Hospital, Barcelona, Spain.
The ErbB2 receptor is one of the four members of the epidermal growth factor (EGFR) family of
receptor tyrosine kinases (RTK), which also includes ErbB1/EGFR, ErbB3 and ErbB4. ErbB2
overexpression is associated with poor prognosis of breast cancer patients. It is known that
ErbB2 receptors can exist on the cell surface as monomers, homodimers and heterodimers with
ErbB1 or ErbB3. It has been shown that trastuzumab antibody, an approved therapeutics for
treatment of ErbB2-overexpresing breast cancer, blocks ErbB2 homodimer activity [1].
In our study, we use a recombinant extracellular domain of the ErbB2, which has a His-tag motif
of 10 His residues at the C-terminal. We study the formation of the ErbB2 homodimer and
ErbB2/trastuzumab complexes by means of a combination of experimental techniques, such as
dynamic and static light scattering as well as chromatography with tetradetection, along with
simulations based on molecular dynamics and hydrodynamic models [2,3]. In this way, we are
able to correlate the solution hydrodynamic data with macromolecular structural parameters.
The experimental results indicate the presence of a variety of complexes between the ErbB2
extracellular domain and trastuzumab in aqueous phase. These complexes show a high degree of
structural flexibility (measured by independent experiments in size- exclusion chromatography
and dynamic light scattering), which is in agreement with our computational results. Under the
experimental condition, our finding reveals the true dynamic features of the complexes in
solution, an insight beyond what is known from the crystal structures. This flexibility does not
allow us to perform 3D reconstruction imaging using TEM experiments [4].
References:
[1] Ghost R, et al. Cancer Res 2011, 71, 1871-1872
[2] Brandt J.P. et al. Biophysical J. 2010, 99, 905-913
[3] Brookes E. et al. Eur. Biophys J., 2010, 39(3), 423-435.
[4] Vicente-Alique E. et al. Eur. Biophys. J. 2011, 40, 835-842.
