February 06, 2025 11:30 am - 12:30 pm ET
Condensed Matter Seminar
LGRT 1033

Trevor GrandPre, Princeton University

Biomolecular condensates are membraneless organelles formed through the phase separation of macromolecules. These molecules typically feature “sticker” regions connected by flexible “linkers”. While linkers facilitate many interactions, an understudied question is how the length of linkers influences condensation via an interplay with other molecular length scales. We investigate this in the algal pyrenoid, a condensate that enhances photosynthesis in Chlamydomonas reinhardtii. In this model system, condensation is driven by well characterized multivalent interactions between the rigid enzyme Rubisco and its flexible partner EPYC1. Our simulations and theory reveal that halving EPYC1 linker lengths decreases critical concentrations by tenfold due to a sensitive molecular “fit” between EPYC1 and Rubisco. We find an inverse relationship between this fit and the tendency to phase separation, with natural Rubisco sticker locations optimizing this process. Additionally, we study how Rubisco-EPYC1 condensates wet membranes, which is necessary for proper pyrenoid function, highlighting how evolution fine-tunes protein phase separation through molecular length scales.