pH-sensing collaboration with the Childers lab out in Nature Communications

The study shows that bacterial ribonucleoprotein bodies (BR-bodies) — membraneless condensates that carry out RNA decay — maintain an acidic internal pH that tunes the enzymes inside them. In other words, bacteria can build a chemically distinct, organelle-like compartment without a membrane.

We changed how the field pictures the inside of a condensate. By reading the fluorescence lifetime of a pH-sensitive reporter (RNase E–pHluorin2) alongside single-molecule localization microscopy, we showed that a single BR-body is not a uniform droplet at all: it contains coexisting, nanoscale acidic sub-domains with sharp internal pH gradients. Paired with a multidimensional analysis of these lifetime maps, this moves condensates from the picture of a well-mixed liquid droplet to spatially heterogeneous chemical networks, where the local chemistry — not the average composition — decides what the enzymes inside actually do.

Congratulations to Moeka Sasazawa and Ryan Cho, and to our collaborators in the Childers and Schrader labs!