Analysis of Thermoresponsive Phase Behavior of Biomolecular Condensates

Biomolecular condensates form membrane-free compartments of cells by liquid-liquid phase separation (LLPS). Various molecular interactions drive phase separation of macromolecules in vitro, such as electrostatic attraction, cation-π, π-π, hydrogen bonding, and hydrophobic interactions. Factors that regulate protein LLPS include external stimuli such as changes in salt concentration, pH, and temperature, etc. One of the factors that can be easily controlled in vitro is temperature, hence the interest in thermosensitive LLPS. As the temperature increases or decreases, thermosensitive protein-based condensates are separated with either a lower critical solution temperature (LCST) or a higher critical solution temperature (UCST).

Fig. 1. Temperature-controlled liquid-liquid phase separation of disordered proteins. ( Dignon GL, et al., 2019)

Customized Services

The thermally responsive phase behavior of biomolecular condensates can be modulated by a variety of factors such as pH, ionic strength, protein concentration, chain length, mutations, and post-translational modifications. Here, CD BioSciences provides professional services to analyze the thermoresponsive phase behavior of LCST and UCST jumps of biomolecular condensates. Among them, tropoelastin and elastin have been used as templates to design elastin-like peptides and elastin-like peptides (ELP and RLP) that exhibit LCST and UCST phase behavior, respectively.

CD BioSciences offers the following strategies to analyze the thermoresponsive phase behavior of biomolecular condensates.

• Coarse-Grained (CG) Models
  We provide coarse-grained models to handle sufficiently large systems and calculate the phase behavior of a large number of protein sequences. Such CG models are constructed at specific temperatures (e.g., room temperature) and do not take into account the temperature dependence of such solvent-mediated interactions. Therefore these models cannot capture properties such as the collapse of disordered proteins that occur with increasing temperature and LCST behavior.
• Temperature-Dependent CG Model
  Our team of experts is committed to developing a transferable temperature-dependent coarse-grained model to directly probe the sequence-dependent thermoresponsive phase behavior of disordered proteins (IDPs). This is an effective approach to inform experimental design and provide insight into the sequence determinants and underlying physics of temperature-dependent LLPS. The advantages of this model are:

✓ Use of knowledge from single-molecule Förster resonance energy transfer (smFRET) experiments and all-atom simulations of disordered protein sizes over a wide temperature range to tune model parameters.

✓ The optimized model can successfully predict the experimentally known phase behavior of large ELP and RLP libraries qualitatively by distinguishing between UCST and LCST.

We provide a temperature-dependent coarse-grained model to directly probe the thermoresponsive phase behavior of biomolecular condensates that explicitly represents amino acid sequences and explains the temperature-dependent solvent-mediated interactions of each amino acid. If you have any special requirements for our services, please feel free to contact us. We are looking forward to working together with your attractive projects.