Temporal gene regulation enables controlled expression of gas vesicles and preserves bacterial viability

Gas vesicles (GVs) are genetically encodable, air-filled protein nanostructures that have rapidly emerged as a versatile platform for biomedical imaging, cell tracking, and therapeutic delivery. However, their heterologous expression in non-native hosts such as Escherichia coli can be challenging due to the complex assembly process, which often involves around ten different proteins and can lead to proteotoxic stress and impair cell growth. Here, we report the observation of a drop in cell density occurring 8 to 16 hours after GV induction in E. coli. To address these, we developed a dual-inducer transcriptional regulation system that enables orthogonal control of GV assembly factor proteins and the shell protein over a range of stoichiometries. Sequential induction in time, in which assembly factor expression is initiated before shell protein expression, restored normal bacterial growth and prevented lysis without compromising GV production. Further analysis revealed that varying the interval between the two induction steps affected both GV yields and cellular stress. By preserving cell integrity with GV expression, our approach enhances the utility of GV-expressing bacteria in applications that demand population-wide cellular stability and facilitates their broader application in biomedical engineering and synthetic biology.