A distinct response to gas vesicle collapse in native, but not heterologous expression hosts

Microbial gas vesicles (GVs) are genetically encodable protein microbubbles that have seen a rapid rise in biomedical interest for their applications as acoustic reporter genes and handles. Unlike artificial microbubbles, their nonlinear response to increasing ultrasound pressure enables modes of imaging with increased contrast and signal. Beyond a characteristic threshold pressure, GVs collapse akin to breaking ballons and release the internal air, an effect that has been used to induce cavitation and distinguish them from background signals. In contrast to the biomedical utility, little is known about the physiological consequences of GV collapse. Here, we demonstrate that GV collapse in a natively GV-positive cell – Dolichospermum flos-aquae – has a distinct transcriptional response, which may be linked to reports of GV recovery post collapse. Conversely, the collapse of GVs in heterologous expressors such as E. coli does not reproduce this behavior. We attempt to provide an initial investigation into the underlying mechanism. Our findings support the existence of a cellular homeostasis mechanism that responds to GV collapse and highlight the importance of the cellular environment in supporting efficient GV assembly and in sensing GV collapse, a feature unique to native GV-producing microbes. Overall design: Cultures of the Cyanobacteria Dolichospermum flos-aquae were grown in triplicates and subjected to sonication before isolation of RNA, followed by RNAseq analysis. Control cells were not subjected to sonication instead. The RNAseq data is intended to display the transcription-level response to collapse of gas vesicles in D. flos-aquae