Excavation of acoustic nanostructures biosynthesis gene clusters by combinatorial strategy.

Gas vesicles (GVs) produced by microorganisms are genetically engineered, air-filled protein nanostructures that have widespread applications in ultrasound imaging and ultrasound-mediated drug delivery. However, constrained by the shape and size, most of them are difficult to be imaged by clinical ultrasound machines, which limits their biomedical applications. Here, we constructed a hybrid gene cluster of the structural gene cluster from Serratia sp. ATCC 39006 and the accessory gene cluster from Bacillus megaterium in Escherichia coli to synthesize a novel gene-encoded gas vesicle with a width of approximately 70 nm and a length of about 100 nm, using a synthetic biology strategy, termed as ARG_S1B. This new type of GVs can be stably produced in bacteria and is able to be imaged by clinical ultrasound machines in vivo and in vitro. Furthermore, the novel nanostructure can be easily engineered for different particle sizes through point saturation mutation, expanding the sources of GVs and providing new insights into the biosynthesis mechanism of GVs.