Proteins seldom act alone. They interact with a variety of other molecules and also with
other proteins to form either homo-oligomers (self-association) or hetero-oligomers
(heterologous association). Oligomerization provides diversity and specificity to many
cellular pathways and play a central role in the regulation of gene expression, the
activity of enzymes, ion channels, receptors, and cell-cell adhesion processes [1, 2]. The
biophysical characterization of heterogenous oligomeric complexes is particularly difficult
due to the complex nature and quality of the samples, and often the available material is
not sufficient for most biophysical methods.
The ribosomal stalk is a heterogeneous pentameric complex directly involved in the
regulation of protein translation. This process is often hijacked by toxins like ricin, which
stalls translation in the cells by binding to subunits of the ribosomal stalk.
Here we show the versatility of MicroScale Thermophoresis (MST) to study the interaction
between a subunit of the ricin toxin and the in-vitro reconstituted ribosomal stalk in its
native form. We also compare the MST results to those obtained with other biophysical
methods such and isothermal calorimetry (ITC), surface plasmon resonance (SPR) and
bio-layer interferometry (BLI). MST allowed the study of this interaction in solution,
without the need for immobilization using very little sample.