Shi Feng

All Publications

• Filament formation drives catalysis by glutaminase enzymes important in cancer progression NATURE COMMUNICATIONS Feng, S., Aplin, C., Nguyen, T. T., Milano, S. K., Cerione, R. A. 2024; 15 (1): 1971

  Abstract

  The glutaminase enzymes GAC and GLS2 catalyze the hydrolysis of glutamine to glutamate, satisfying the 'glutamine addiction' of cancer cells. They are the targets of anti-cancer drugs; however, their mechanisms of activation and catalytic activity have been unclear. Here we demonstrate that the ability of GAC and GLS2 to form filaments is directly coupled to their catalytic activity and present their cryo-EM structures which provide a view of the conformational states essential for catalysis. Filament formation guides an 'activation loop' to assume a specific conformation that works together with a 'lid' to close over the active site and position glutamine for nucleophilic attack by an essential serine. Our findings highlight how ankyrin repeats on GLS2 regulate enzymatic activity, while allosteric activators stabilize, and clinically relevant inhibitors block, filament formation that enables glutaminases to catalyze glutaminolysis and support cancer progression.

  View details for DOI 10.1038/s41467-024-46351-3

  View details for Web of Science ID 001179853600006

  View details for PubMedID 38438397

  View details for PubMedCentralID PMC10912226

• Cryptochrome-Timeless structure reveals circadian clock timing mechanisms. Nature Lin, C., Feng, S., DeOliveira, C. C., Crane, B. R. 2023; 617 (7959): 194-199

  Abstract

  Circadian rhythms influence many behaviours and diseases1,2. They arise from oscillations in gene expression caused by repressor proteins that directly inhibit transcription of their own genes. The fly circadian clock offers a valuable model for studying these processes, wherein Timeless (Tim) plays a critical role in mediating nuclear entry of the transcriptional repressor Period (Per) and the photoreceptor Cryptochrome (Cry) entrains the clock by triggering Tim degradation in light2,3. Here, through cryogenic electron microscopy of the Cry-Tim complex, we show how a light-sensing cryptochrome recognizes its target. Cry engages a continuous core of amino-terminal Tim armadillo repeats, resembling how photolyases recognize damaged DNA, and binds a C-terminal Tim helix, reminiscent of the interactions between light-insensitive cryptochromes and their partners in mammals. The structure highlights how the Cry flavin cofactor undergoes conformational changes that couple to large-scale rearrangements at the molecular interface, and how a phosphorylated segment in Tim may impact clock period by regulating the binding of Importin-α and the nuclear import of Tim-Per4,5. Moreover, the structure reveals that the N terminus of Tim inserts into the restructured Cry pocket to replace the autoinhibitory C-terminal tail released by light, thereby providing a possible explanation for how the long-short Tim polymorphism adapts flies to different climates6,7.

  View details for DOI 10.1038/s41586-023-06009-4

  View details for PubMedID 37100907

  View details for PubMedCentralID PMC11034853

• Embryonic Stem Cell-Derived Extracellular Vesicles Maintain ESC Stemness by Activating FAK. Developmental cell Hur, Y. H., Feng, S., Wilson, K. F., Cerione, R. A., Antonyak, M. A. 2021; 56 (3): 277-291.e6

  Abstract

  It is critical that epiblast cells within blastocyst-stage embryos receive the necessary regulatory cues to remain pluripotent until the appropriate time when they are stimulated to undergo differentiation, ultimately to give rise to an entire organism. Here, we show that exposure of embryonic stem cells (ESCs), which are the in vitro equivalents of epiblasts, to ESC-derived extracellular vesicles (EVs) helps to maintain their stem cell properties even under culture conditions that would otherwise induce differentiation. EV-treated ESCs continued to express stemness genes, preserving their pluripotency and ability to generate chimeric mice. These effects were triggered by fibronectin bound to the surfaces of EVs, enabling them to interact with ESC-associated integrins and activate FAK more effectively than fibronectin alone. Overall, these findings highlight a potential regulatory mechanism whereby epiblast cells, via their shed EVs, create an environment within the blastocyst that prevents their premature differentiation and maintains their pluripotent state.

  View details for DOI 10.1016/j.devcel.2020.11.017

  View details for PubMedID 33321103

  View details for PubMedCentralID PMC8005871