Photon Science Directorate
Showing 41-43 of 43 Results
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Debbie Senesky
Associate Professor of Aeronautics and Astronautics, of Electrical Engineering and Senior Fellow at the Precourt Institute for Energy and, by courtesy, of Photon Science
BioDebbie G. Senesky is an Associate Professor at Stanford University in the Aeronautics and Astronautics Department and the Electrical Engineering Department. In addition, she is the Principal Investigator of the EXtreme Environment Microsystems Laboratory (XLab). Her research interests include the development of nanomaterials for extreme harsh environments, high-temperature electronics for Venus exploration, and microgravity synthesis of nanomaterials. In the past, she has held positions at GE Sensing (formerly known as NovaSensor), GE Global Research Center, and Hewlett Packard. She received the B.S. degree (2001) in mechanical engineering from the University of Southern California. She received the M.S. degree (2004) and Ph.D. degree (2007) in mechanical engineering from the University of California, Berkeley. Prof. Senesky is the Site Director of nano@stanford. She is currently the co-editor of two technical journals: IEEE Journal of Microelectromechanical Systems and Sensors. In recognition of her research, she received the Presidential Early Career Award for Scientists and Engineers (PECASE) in 2025, Emerging Leader Abie Award from AnitaB.org in 2018, Early Faculty Career Award from the National Aeronautics and Space Administration (NASA) in 2012, Gabilan Faculty Fellowship Award in 2012, and Sloan Ph.D. Fellowship from the Alfred P. Sloan Foundation in 2004.
Prof. Senesky's career path and research has been featured by Scientific American, Seeker, People Behind the Science podcast, The Future of Everything radio show, Space.com, and NPR's Tell Me More program. More information about Prof. Senesky can be found at https://xlab.stanford.edu and on Instagram (@astrodebs). -
Christopher John Tassone
Associate Professor (Research) of Photon Science
BioChristopher J. Tassone, PhD is the Associate Lab Director for the Energy Sciences Directorate. His scientific interests lie in the development and characterization of advanced materials for energy. Dr. Tassone’s research addresses critical challenges in energy transition materials, plastics production, and catalysis, with the goal of improving energy technologies and utilizing domestically secure feedstocks. He is an expert in synchrotron-based X-ray scattering techniques, which he uses to probe the time resolved structure of materials as they are synthesized, and how they evolve under operation. He compliments this focus on developing operando and in-situ methods, with the development and application of machine learning for data interpretation and experimental steering. Through this work, Dr. Tassone helps accelerate the discovery of innovative materials for energy and catalysis.
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Soichi Wakatsuki
Professor of Photon Science and of Structural Biology
On Leave from 05/01/2026 To 01/31/2027Current Research and Scholarly InterestsUbiquitin signaling: structure, function, and therapeutics
Ubiquitin is a small protein modifier that is ubiquitously produced in the cells and takes part in the regulation of a wide range of cellular activities such as gene transcription and protein turnover. The key to the diversity of the ubiquitin roles in cells is that it is capable of interacting with other cellular proteins either as a single molecule or as different types of chains. Ubiquitin chains are produced through polymerization of ubiquitin molecules via any of their seven internal lysine residues or the N-terminal methionine residue. Covalent interaction of ubiquitin with other proteins is known as ubiquitination which is carried out through an enzymatic cascade composed of the ubiquitin-activating (E1), ubiquitin-conjugating (E2), and ubiquitin ligase (E3) enzymes. The ubiquitin signals are decoded by the ubiquitin-binding domains (UBDs). These domains often specifically recognize and non-covalently bind to the different ubiquitin species, resulting in distinct signaling outcomes.
We apply a combination of the structural (including protein crystallography, small angle x-ray scattering, cryo-electron microscopy (Cryo-EM) etc.), biocomputational and biochemical techniques to study the ubiquitylation and deubiquitination processes, and recognition of the ubiquitin chains by the proteins harboring ubiquitin-binding domains. Current research interests including SARS-COV2 proteases and their interactions with polyubiquitin chains and ubiquitin pathways in host cell responses, with an ultimate goal of providing strategies for effective therapeutics with reduced levels of side effects.
Protein self-assembly processes and applications.
The Surface layers (S-layers) are crystalline protein coats surrounding microbial cells. S-layer proteins (SLPs) regulate their extracellular, self-assembly by crystallizing when exposed to an environmental trigger. We have demonstrated that the Caulobacter crescentus SLP readily crystallizes into sheets both in vivo and in vitro via a calcium-triggered multistep assembly pathway. Observing crystallization using a time course of Cryo-EM imaging has revealed a crystalline intermediate wherein N-terminal nucleation domains exhibit motional dynamics with respect to rigid lattice-forming crystallization domains. Rate enhancement of protein crystallization by a discrete nucleation domain may enable engineering of kinetically controllable self-assembling 2D macromolecular nanomaterials. In particular, this is inspiring designing robust novel platform for nano-scale protein scaffolds for structure-based drug design and nano-bioreactor design for the carbon-cycling enzyme pathway enzymes. Current research focuses on development of nano-scaffolds for high throughput in vitro assays and structure determination of small and flexible proteins and their interaction partners using Cryo-EM, and applying them to cancer and anti-viral therapeutics.
Multiscale imaging and technology developments.
Multimodal, multiscale imaging modalities will be developed and integrated to understand how molecular level events of key enzymes and protein network are connected to cellular and multi-cellular functions through intra-cellular organization and interactions of the key machineries in the cell. Larger scale organization of these proteins will be studied by solution X-ray scattering and Cryo-EM. Their spatio-temporal arrangements in the cell organelles, membranes, and cytosol will be further studied by X-ray fluorescence imaging and correlated with cryoEM and super-resolution optical microscopy. We apply these multiscale integrative imaging approaches to biomedical, and environmental and bioenergy research questions with Stanford, DOE national labs, and other domestic and international collaborators.