Recombinantly Expressed Gas Vesicles as Nanoscale Contrast Agents for Ultrasound and Hyperpolarized MRI
Ultrasound and hyperpolarized magnetic resonance imaging enable the visualization of biological processes in deep tissues. However, few molecular contrast agents are available to connect these modalities to specific aspects of biological function. We recently discovered that a unique class of gas‐filled protein nanostructures known as gas vesicles could serve as nanoscale molecular reporters for these modalities. However, the need to produce these nanostructures via expression in specialized cultures of cyanobacteria or haloarchaea limits their broader adoption by other laboratories and hinders genetic engineering of their properties. Here, we describe recombinant expression and purification of Bacillus megaterium gas vesicles using a common laboratory strain of Escherichia coli, and characterize the physical, acoustic, and magnetic resonance properties of these nanostructures. Recombinantly expressed gas vesicles produce ultrasound and hyperpolarized ^(129)Xe MRI contrast at subnanomolar concentrations, thus validating a simple platform for their production and engineering.
© 2018 American Institute of Chemical Engineers. Issue Online: 25 July 2018; Version of Record online: 08 March 2018; Accepted manuscript online: 23 February 2018; Manuscript revised: 07 February 2018; Manuscript received: 10 November 2017. This research was supported by the NIH (R01-EB018975 to MGS) and HFSP (RGP0050 to MGS and LS). A.L. is supported by the NSF graduate research fellowship (award number 1144469) and the NIH Biotechnology Leaders Program. A.F. is supported by the NSERC graduate fellowship. Related work in the Shapiro Lab is also supported by the Heritage Medical Research Institute, the Pew Charitable Trust, the Sontag Foundation, the Burroughs Wellcome Fund and the Packard Foundation.
Accepted Version - nihms948739.pdf