Molecular features driving phase separation
Our future studies, described in more detail in the sections of individual lab members, are directed in three broad areas. First, we are working to understand the physical principles that enable different classes of macromolecules to undergo LLPS. This includes the surface properties and inter-domain linker sequences of multi-domain proteins involved in signal transduction, as well as the sequence properties of disordered elements such as those found in RNA binding proteins. On the latter, we are interested both in sequence features that drive LLPS, as well as those that promote maturation to amyloid-like fibers. We also are using these various systems to understand how the physical properties of molecules dictate the macroscopic properties of their phase separated structures. These studies involve low-throughput protein design followed by biochemical and cell biological analyses, and also development of high-throughput in vitro screens to examine the properties of thousands of proteins at a time.
To ground these investigations in physical theory, we are working collaboratively with several groups in condensed matter physics—Milo Lin, Rohit Pappu and Ned Wingreen.
Ultrastructure of condensates
In a final area, we are just beginning studies of the ultrastructure of condensates, both reconstituted in vitro and naturally in cells. These analyses will show whether condensates have organized internal structures, and if so, how these differ in natural and diseased conditions (e.g. in cells expressing PML-RAR fusions that cause promyelocytic leukemia, or mutants of the FUS protein that cause ALS). This work involves a combination of super-resolution fluorescence microscopy, as well as collaborative cryo-electron tomography. Ultimately our goal is to develop a comprehensive, quantitative understanding of the composition, dynamics and structure of representative biomolecular condensates, and to discover broadly applicable principles on how these structures function and evolve in biology.
For further details on specific projects we invite you to explore the descriptions found on individual lab members’ pages.