An official website of the United States government
Cutting-edge photonic devices frequently rely on microparticle components to focus and manipulate light. Conventional methods used to produce these microparticle components frequently offer limited control of their structural properties or require low-throughput nanofabrication of more complex structures. Here, we employ a synthetic biology approach to produce environmentally friendly, living microlenses with tunable structural properties. We engineeredEscherichia colibacteria to display the silica biomineralization enzyme silicatein from aquatic sea sponges. Our silicatein-expressing bacteria can self-assemble a shell of polysilicate “bioglass” around themselves. Remarkably, the polysilicate-encapsulated bacteria can focus light into intense nanojets that are nearly an order of magnitude brighter than unmodified bacteria. Polysilicate-encapsulated bacteria are metabolically active for up to 4 mo, potentially allowing them to sense and respond to stimuli over time. Our data demonstrate that synthetic biology offers a pathway for producing inexpensive and durable photonic components that exhibit unique optical properties.
more »
« less
Tunable light-focusing behavior of engineered bacterial microlenses with controllable shapes
Abstract Recently, engineered bacterial cells have been shown to behave as optically-active photonic devices comparable to industrially fabricated microlenses1. Bacterial cells can be encapsulated within a layer of polysilicate through surface display of the sea sponge enzyme silicatein, which mineralizes a polysilicate coating. The addition of this polysilicate layer significantly enhances the ability of these cells to guide, scatter, and focus light1. However, this previous technique was limited to creating rod-shaped microlenses, which are not ideal for all applications. Here we expand upon this technology by engineering the shapes of silicatein-displaying bacterial cells. Through the overexpression of the genesbolA2–5andsulA6,7or through the use of the drug A228,9, we are able to alterEscherichia colicells from their characteristic rod-like shape to either spherical or filamentous forms. Round cells encapsulated in polysilicate were shown to scatter light more intensely and symmetrically than rod-shaped cells, while encapsulated filamentous cells were shown to guide light similarly to an optical fiber. This control over the size and shape of optically-active cells is a major advancement towards developing bio-engineered photonic devices such as nanophotonic waveguides, spherical microlens arrays, and advanced biosensors.
more »
« less
- Award ID(s):
- 2230641
- PAR ID:
- 10660630
- Publisher / Repository:
- bioRxiv
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Bactofilins are rigid, nonpolar bacterial cytoskeletal filaments that link cellular processes to specific curvatures of the cytoplasmic membrane. Although homologs of bactofilins have been identified in archaea and eukaryotes, functional studies have remained confined to bacterial systems. Here, we characterize representatives of two families of archaeal bactofilins from the pleomorphic archaeonHaloferax volcanii, halofilin A (HalA) and halofilin B (HalB). HalA and HalB polymerize in vitro, assembling into straight bundles. HalA polymers are highly dynamic and accumulate at positive membrane curvatures in vivo, whereas HalB forms more static foci that localize in areas of local negative curvatures on the outer cell surface. Gene deletions and live-cell imaging show that halofilins are critical in maintaining morphological integrity during shape transition from disk (sessile) to rod (motile). Morphological defects in ΔhalAresult in accumulation of highly positive curvatures in rods but not in disks. Conversely, disk-shaped cells are exclusively affected byhalBdeletion, resulting in flatter cells. Furthermore, while ΔhalAand ΔhalBcells imprecisely determine the future division plane, defects arise predominantly during the disk-to-rod shape remodeling. The deletion ofhalAin the haloarchaeonHalobacterium salinarum, whose cells are consistently rod-shaped, impacted morphogenesis but not cell division. Increased levels of halofilins enforced drastic deformations in cells devoid of the S-layer, suggesting that HalB polymers are more stable at defective S-layer lattice regions. Our results suggest that halofilins might play a significant mechanical scaffolding role in addition to possibly directing envelope synthesis.more » « less
-
Nanoparticle therapeutic delivery is influenced by many factors including physical, chemical, and biophysical properties along with local vascular conditions. In recent years, nanoparticles of various shapes have been fabricated and have shown significant impact on transport efficiency. Identification of which nanoparticle shape helps to improve the therapeutic delivery process allows for enhanced therapeutic effects, yet is hard to be quantified in vivo due to the complex nature of the in vivo environment. In this work, we turn to biological models as a guide for informing improved nanoparticle therapeutic delivery, and quantify the contribution of various factors on delivery efficiency. Here we show that with a mimetic blood vessel, improved therapeutic delivery is achieved using long filamentous rod nanoparticles under low pressure conditions. When considering medium pressure conditions, a combination of nanoparticle shapes presents improved therapeutic delivery over the treatment time-course starting with long filamentous rod nanoparticles, followed by short rod nanoparticles. Conditions of high pressure required a combination of short rod nanoparticles, followed by spherical nanoparticles to achieve enhanced therapeutic delivery. Overall, improvement of therapeutic delivery via nanoparticle carriers is likely to require a combination of nanoparticle shapes administered at different times over the treatment time-course, given patient specific conditions.more » « less
-
null (Ed.)The cell morphology of rod-shaped bacteria is determined by the rigid net of peptidoglycan forming the cell wall. Alterations to the rod shape, such as the curved rod, occur through manipulating the process of cell wall synthesis. The human pathogen Vibrio cholerae typically exists as a curved rod, but straight rods have been observed under certain conditions. While this appears to be a regulated process, the regulatory pathways controlling cell shape transitions in V. cholerae and the benefits of switching between rod and curved shape have not been determined. We demonstrate that cell shape in V. cholerae is regulated by the bacterial second messenger cyclic dimeric guanosine monophosphate (c-di-GMP) by posttranscriptionally repressing expression of crvA , a gene encoding an intermediate filament-like protein necessary for curvature formation in V. cholerae. This regulation is mediated by the transcriptional cascade that also induces production of biofilm matrix components, indicating that cell shape is coregulated with V. cholerae ’s induction of sessility. During microcolony formation, wild-type V. cholerae cells tended to exist as straight rods, while genetically engineering cells to maintain high curvature reduced microcolony formation and biofilm density. Conversely, straight V. cholerae mutants have reduced swimming speed when using flagellar motility in liquid. Our results demonstrate regulation of cell shape in bacteria is a mechanism to increase fitness in planktonic and biofilm lifestyles.more » « less
-
Abstract Understanding the behaviors of contractile actomyosin systems requires precise spatiotemporal control of filamentous myosin activity. Here, we develop a tool for optical control of contractility by extending the MyLOV family of gearshifting motors to create engineered filamentous myosins that change velocity in response to blue light. We characterize these minifilaments usingin vitrosingle-molecule tracking assays, contractility assays in reconstituted actin networks, and imaging of contractile phenotypes inDrosophilaS2 cells. The minifilaments change speed and/or direction when illuminated, display speeds that fall within and beyond the relevant physiological range, and display high processivities. Additionally, minifilament-driven contraction rates increase in blue light bothin vitroand in S2 cells. Finally, we develop an alternative design for minifilaments that only interact processively with actin in blue light. Engineered minifilaments can be used to dissect behaviors such as self-organization and mechanotransduction in contractile systems bothin vitroand in cells and tissues.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Posted Content:
- https://doi.org/10.64898/2025.12.17.694918
