Poster Presentation The 47th Lorne Conference on Protein Structure and Function 2022

Investigation of the Mediator Complex in Ceanorhabditis elegans. (#130)

Joanne Coyle 1 , Wei Cao 1 , Roger Pocock 1 , Senthil Arumugam 1
  1. Monash University, Clayton, VIC, Australia

In the last two decades liquid-liquid phase separation (LLPS) has become an integral part of cell biology and has enhanced our understanding of protein dynamics within cells. LLPS represents a phenomenon whereby proteins separate from their original phase into their own phase separated compartment, similarly to how oil separates in water1. This compartment or “droplet” is 10-100 times more concentrated in proteins than its surrounding milieu and provides the basis for containing proteins without the use of a biological membane2,3. This project focuses on one possible example of LLPS – the Mediator complex in C. elegans. The Mediator complex is made up of ~30 subunits, and is involved in transcription. Specifically, the Mediator is important for the preinitiator complex, and for translating signals from transcription factors to RNA Pol II4. By focusing on two subunits – Mdt26 and Mdt29, this project investigates if these proteins are undergoing LLPS. In particular, this project aims to confirm if the Mediator complex is phase separating through fluorescence recovery after photobleaching (FRAP) and heat shock of the worm samples5. Techniques such as fluorescence lifetime imaging microscopy (FLIM) and Fӧrster resonance energy transfer (FRET) are also being used to study these proteins. Overall, this project encompasses a thorough investigation into LLPS using C. elegans as a model organism6.  

  1. Hyman, A. A., Weber, C. A. & Jülicher, F. Liquid-Liquid Phase Separation in Biology. Rev. Cell Dev. Biol. 30, 39–58 (2014).
  2. Mitrea, D. M. & Kriwacki, R. W. Phase separation in biology; functional organization of a higher order. Cell Commun. Signal. 14, 1 (2016).
  3. Kanaan, N. M., Hamel, C., Grabinski, T. & Combs, B. Liquid-liquid phase separation induces pathogenic tau conformations in vitro. Commun. 11, 2809 (2020).
  4. Poss, Z. C., Ebmeier, C. C. & Taatjes, D. J. The Mediator complex and transcription regulation. Rev. Biochem. Mol. Biol. 48, 575–608 (2013).
  5. Alberti, S., Gladfelter, A. & Mittag, T. Considerations and Challenges in Studying Liquid-Liquid Phase Separation and Biomolecular Condensates. Cell 176, 419–434 (2019).
  6. Kaletta, T. & Hengartner, M. O. Finding function in novel targets: C. elegans as a model organism. Rev. Drug Discov. 5, 387–399 (2006).