Novel Thermostable Flavin‐binding Fluorescent Proteins from Thermophilic Organisms

Flavin‐binding fluorescent proteins (FbFPs) are small, oxygen‐independent in vivo reporters, derived from Light Oxygen Voltage (LOV) domains of photoreceptors. Here, we investigated the thermostability of existing, as well as novel FbFPs, whose genes were identified in genome sequences of various thermophilic bacteria as well as metagenomic libraries from hot springs in the Yellowstone National Park. Detailed in vitro analyses revealed that two of those fluorescent reporter proteins were highly thermostable, exhibiting melting temperatures above 75°C. Flavin‐binding fluorescent proteins (FbFPs) are small, oxygen‐independent fluorescent reporter proteins, derived from Light Oxygen Voltage (LOV) domains, which act as blue light photoreceptors in bacteria and plants. We investigated the thermostability of existing FbFPs and designed new FbFPs based on LOV domains found in genome sequences of various thermophilic bacteria. Two of those novel fluorescent reporter proteins are highly thermostable, exhibiting melting temperatures above 75°C.