Education & Certifications


  • BA, University of Pennsylvania, Biochemistry; Biophysics; Physics (2012)

All Publications


  • Protein Self-Assembly Drives Surface Layer Biogenesis and Maintenance in C. crescentus Herrmann, J., Comerci, C., Yoon, J., Jabbarpour, F., Shapiro, L., Wakatsuki, S., Moerner, W. E. CELL PRESS. 2019: 159A
  • Multi-Step 2D Protein Crystallization via Structural Changes within an Ordered Lattice Herrmann, J., Comerci, C. J., Jabbarpour, F., Shapiro, L., Moerner, W. E., Wakatsuki, S. CELL PRESS. 2019: 194A
  • Revealing Nanoscale Morphology of the Primary Cilium Using Super-Resolution Fluorescence Microscopy. Biophysical journal Yoon, J., Comerci, C. J., Weiss, L. E., Milenkovic, L., Stearns, T., Moerner, W. E. 2018

    Abstract

    Super-resolution (SR) microscopy has been used to observe structural details beyond the diffraction limit of 250nm in a variety of biological and materials systems. By combining this imaging technique with both computer-vision algorithms and topological methods, we reveal and quantify the nanoscale morphology of the primary cilium, a tiny tubular cellular structure (2-6 mum long and 200-300nm in diameter). The cilium in mammalian cells protrudes out of the plasma membrane and is important in many signaling processes related to cellular differentiation and disease. After tagging individual ciliary transmembrane proteins, specifically Smoothened, with single fluorescent labels in fixed cells, we use three-dimensional (3D) single-molecule SR microscopy to determine their positions with a precision of 10-25nm. We gain a dense, pointillistic reconstruction of the surfaces of many cilia, revealing large heterogeneity in membrane shape. A Poisson surface reconstruction algorithm generates a fine surface mesh, allowing us to characterize the presence of deformations by quantifying the surface curvature. Upon impairment of intracellular cargo transport machinery by genetic knockout or small-molecule treatment of cells, our quantitative curvature analysis shows significant morphological differences not visible by conventional fluorescence microscopy techniques. Furthermore, using a complementary SR technique, two-color, two-dimensional stimulated emission depletion microscopy, we find that the cytoskeleton in the cilium, the axoneme, also exhibits abnormal morphology in the mutant cells, similar to our 3D results on the Smoothened-measured ciliary surface. Our work combines 3D SR microscopy and computational tools to quantitatively characterize morphological changes of the primary cilium under different treatments and uses stimulated emission depletion to discover correlated changes in the underlying structure. This approach can be useful for studying other biological or nanoscale structures of interest.

    View details for PubMedID 30598282

  • Two-Color Sted Microscopy to Visualize S-Layer Biogenesis in Caulobacter Crescentus Comerci, C. J., Herrmann, J., Shapiro, L., Wakatsuki, S., Moerner, W. E. CELL PRESS. 2018: 613A
  • Super-Resolution Microscopy and Single-Protein Tracking in Live Bacteria Using a Genetically Encoded, Photostable Fluoromodule. Current protocols in cell biology Saurabh, S., Perez, A. M., Comerci, C. J., Shapiro, L., Moerner, W. E. 2017; 75: 4.32.1–4.32.22

    Abstract

    Visualization of dynamic protein structures in live cells is crucial for understanding the mechanisms governing biological processes. Fluorescence microscopy is a sensitive tool for this purpose. In order to image proteins in live bacteria using fluorescence microscopy, one typically genetically fuses the protein of interest to a photostable fluorescent tag. Several labeling schemes are available to accomplish this. Particularly, hybrid tags that combine a fluorescent or fluorogenic dye with a genetically encoded protein (such as enzymatic labels) have been used successfully in multiple cell types. However, their use in bacteria has been limited due to challenges imposed by a complex bacterial cell wall. Here, we describe the use of a genetically encoded photostable fluoromodule that can be targeted to cytosolic and membrane proteins in the Gram negative bacterium Caulobacter crescentus. Additionally, we summarize methods to use this fluoromodule for single protein imaging and super-resolution microscopy using stimulated emission depletion. © 2017 by John Wiley & Sons, Inc.

    View details for PubMedID 28627757

  • Super-resolution Imaging of Live Bacteria Cells Using a Genetically Directed, Highly Photostable Fluoromodule. Journal of the American Chemical Society Saurabh, S., Perez, A. M., Comerci, C. J., Shapiro, L., Moerner, W. E. 2016; 138 (33): 10398-10401

    Abstract

    The rapid development in fluorescence microscopy and imaging techniques has greatly benefited our understanding of the mechanisms governing cellular processes at the molecular level. In particular, super-resolution microscopy methods overcome the diffraction limit to observe nanoscale cellular structures with unprecedented detail, and single-molecule tracking provides precise dynamic information about the motions of labeled proteins and oligonucleotides. Enhanced photostability of fluorescent labels (i.e., maximum emitted photons before photobleaching) is a critical requirement for achieving the ultimate spatio-temporal resolution with either method. While super-resolution imaging has greatly benefited from highly photostable fluorophores, a shortage of photostable fluorescent labels for bacteria has limited its use in these small but relevant organisms. In this study, we report the use of a highly photostable fluoromodule, dL5, to genetically label proteins in the Gram-negative bacterium Caulobacter crescentus, enabling long-time-scale protein tracking and super-resolution microscopy. dL5 imaging relies on the activation of the fluorogen Malachite Green (MG) and can be used to label proteins sparsely, enabling single-protein detection in live bacteria without initial bleaching steps. dL5-MG complexes emit 2-fold more photons before photobleaching compared to organic dyes such as Cy5 and Alexa 647 in vitro, and 5-fold more photons compared to eYFP in vivo. We imaged fusions of dL5 to three different proteins in live Caulobacter cells using stimulated emission depletion microscopy, yielding a 4-fold resolution enhancement compared to diffraction-limited imaging. Importantly, dL5 fusions to an intermediate filament protein CreS are significantly less perturbative compared to traditional fluorescent protein fusions. To the best of our knowledge, this is the first demonstration of the use of fluorogen activating proteins for super-resolution imaging in live bacterial cells.

    View details for DOI 10.1021/jacs.6b05943

    View details for PubMedID 27479076

    View details for PubMedCentralID PMC4996739

  • Cby1 promotes Ahi1 recruitment to a ring-shaped domain at the centriole-cilium interface and facilitates proper cilium formation and function MOLECULAR BIOLOGY OF THE CELL Lee, Y. L., Sante, J., Comerci, C. J., Cyge, B., Menezes, L. F., Li, F., Germino, G. G., Moerner, W. E., Takemaru, K., Stearns, T. 2014; 25 (19): 2919-2933

    Abstract

    Defects in centrosome and cilium function are associated with phenotypically related syndromes called ciliopathies. Cby1, the mammalian orthologue of the Drosophila Chibby protein, localizes to mature centrioles, is important for ciliogenesis in multiciliated airway epithelia in mice, and antagonizes canonical Wnt signaling via direct regulation of β-catenin. We report that deletion of the mouse Cby1 gene results in cystic kidneys, a phenotype common to ciliopathies, and that Cby1 facilitates the formation of primary cilia and ciliary recruitment of the Joubert syndrome protein Arl13b. Localization of Cby1 to the distal end of mature centrioles depends on the centriole protein Ofd1. Superresolution microscopy using both three-dimensional SIM and STED reveals that Cby1 localizes to an ∼250-nm ring at the distal end of the mature centriole, in close proximity to Ofd1 and Ahi1, a component of the transition zone between centriole and cilium. The amount of centriole-localized Ahi1, but not Ofd1, is reduced in Cby1(-/-) cells. This suggests that Cby1 is required for efficient recruitment of Ahi1, providing a possible molecular mechanism for the ciliogenesis defect in Cby1(-/-) cells.

    View details for DOI 10.1091/mbc.E14-02-0735

    View details for Web of Science ID 000343124100004

    View details for PubMedCentralID PMC4230582

  • Cby1 promotes Ahi1 recruitment to a ring-shaped domain at the centriole-cilium interface and facilitates proper cilium formation and function. Molecular biology of the cell Lee, Y. L., Santé, J., Comerci, C. J., Cyge, B., Menezes, L. F., Li, F., Germino, G. G., Moerner, W. E., Takemaru, K., Stearns, T. 2014; 25 (19): 2919-2933

    Abstract

    Defects in centrosome and cilium function are associated with phenotypically related syndromes called ciliopathies. Cby1, the mammalian orthologue of the Drosophila Chibby protein, localizes to mature centrioles, is important for ciliogenesis in multiciliated airway epithelia in mice, and antagonizes canonical Wnt signaling via direct regulation of β-catenin. We report that deletion of the mouse Cby1 gene results in cystic kidneys, a phenotype common to ciliopathies, and that Cby1 facilitates the formation of primary cilia and ciliary recruitment of the Joubert syndrome protein Arl13b. Localization of Cby1 to the distal end of mature centrioles depends on the centriole protein Ofd1. Superresolution microscopy using both three-dimensional SIM and STED reveals that Cby1 localizes to an ∼250-nm ring at the distal end of the mature centriole, in close proximity to Ofd1 and Ahi1, a component of the transition zone between centriole and cilium. The amount of centriole-localized Ahi1, but not Ofd1, is reduced in Cby1(-/-) cells. This suggests that Cby1 is required for efficient recruitment of Ahi1, providing a possible molecular mechanism for the ciliogenesis defect in Cby1(-/-) cells.

    View details for DOI 10.1091/mbc.E14-02-0735

    View details for PubMedID 25103236