A5025568767- Protein Kinase Regulation and GTPase Signaling
- Microbial Natural Products and Biosynthesis
- Protein Structure and Dynamics
- Enzyme Structure and Function
- Ubiquitin and proteasome pathways
- RNA modifications and cancer
- Glycosylation and Glycoproteins Research
- Cellular transport and secretion
- RNA and protein synthesis mechanisms
- Receptor Mechanisms and Signaling
- ATP Synthase and ATPases Research
- Mitochondrial Function and Pathology
- Ion channel regulation and function
- Neuroscience and Neuropharmacology Research
- Endoplasmic Reticulum Stress and Disease
- Microbial Metabolic Engineering and Bioproduction
- PI3K/AKT/mTOR signaling in cancer
- Advanced Electron Microscopy Techniques and Applications
- Peptidase Inhibition and Analysis
- Antifungal resistance and susceptibility
- Mesoporous Materials and Catalysis
- RNA regulation and disease
- Protein Tyrosine Phosphatases
- Photosynthetic Processes and Mechanisms
- Tuberous Sclerosis Complex Research
Princess Margaret Cancer Centre
2014-2025
University Health Network
2009-2025
University of Toronto
2014-2025
Ontario Institute for Cancer Research
2009-2019
Hospital for Sick Children
2016-2018
McMaster University
2007-2012
Canada Research Chairs
2012
Cancer Institute (WIA)
2009
Significance KRAS (Kirsten rat sarcoma viral oncogene homolog) is frequently mutated in pancreatic, colon, and lung tumors, which predicts poor clinical outcome, whereas germ-line mutations are associated with developmental disorders, including Noonan syndrome. Although K-RAS an attractive anticancer target, no clinically successful inhibitors available. Most disease-associated elevate the activated GTP-bound form of KRAS; however, some remain unexplained. signals from cellular membranes;...
CD22 maintains a baseline level of B-cell inhibition to keep humoral immunity in check. As B-cell-restricted antigen, is targeted therapies against dysregulated B cells that cause autoimmune diseases and blood cancers. Here we report the crystal structure human at 2.1 Å resolution, which reveals specificity for α2-6 sialic acid ligands dictated by pre-formed β-hairpin as unique mode recognition across acid-binding immunoglobulin-type lectins. The ectodomain adopts an extended conformation...
Viruses evade the innate immune response by suppressing production or activity of cytokines such as type I interferons (IFNs). Here we report discovery a mechanism which SARS-CoV-2 virus coopts an intrinsic cellular machinery to suppress key immunostimulatory cytokine IFN-β. We reveal that encoded nonstructural protein 2 (NSP2) directly interacts with GIGYF2 protein. This interaction enhances binding mRNA cap-binding 4EHP, thereby repressing translation Ifnb1 mRNA. Depletion 4EHP...
Sialic acids linked to glycoproteins and glycolipids are important mediators of cell protein recognition events. These sugar residues removed by neuraminidases (sialidases). Neuraminidase-1 (sialidase-1 or NEU1) is a ubiquitously expressed mammalian sialidase located in lysosomes on the membrane. Because its modulation multiple signaling processes, it potential therapeutic target for cancers immune disorders. Genetic defects NEU1 protective cathepsin A (PPCA, CTSA) cause lysosomal storage...
Heterotrimeric G proteins can be regulated by posttranslational modifications, including ubiquitylation. KCTD5, a pentameric substrate receptor protein consisting of an N-terminal BTB domain and C-terminal domain, engages CUL3 to form the central scaffold cullin-RING E3 ligase complex (CRL3 KCTD5 ) that ubiquitylates Gβγ reduces levels in cells. The cryo-EM structure 5:5:5 KCTD5/CUL3 NTD /Gβ 1 γ 2 assembly reveals highly dynamic with rotations over 60° between /CUL3 CTD /Gβγ moieties...
One of the mechanisms that minimize aberrant cross-talk between cAMP- and cGMP-dependent signaling pathways relies on selectivity cAMP binding domains (CBDs). For instance, CBDs two critical eukaryotic receptors, i.e. protein kinase A (PKA) exchange activated by (EPAC), are both selectively cAMP. However, underlying their versus cGMP quite distinct. In PKA this is controlled mainly at level ligand affinity, whereas in EPAC it mostly determined allostery. Currently, molecular basis for these...
Like most Ras superfamily proteins, the GTPase domain of homologue enriched in brain (Rheb) is tethered to cellular membranes through a prenylated cysteine flexible C-terminal region; however, little known about how Rheb or other GTPases interact with membrane this environment may affect their functions. We used NMR methods characterize nanodiscs, monodisperse protein-encapsulated lipid bilayers diameter 10 nm. Membrane conjugation markedly reduced rate intrinsic nucleotide exchange, while...
The cyclic-AMP binding domain (CBD) is the central regulatory unit of exchange proteins activated by cAMP (EPAC). CBD maintains EPAC in a state auto-inhibition absence allosteric effector, cAMP. When binds to such released, leading activation. It has been shown that key feature cAMP-dependent activation process partial destabilization structurally conserved hinge helix at C-terminus CBD. However, role this currently not fully understood. Here we utilize series progressive deletion mutants...
Rising drug resistance among pathogenic fungi, paired with a limited antifungal arsenal, poses an increasing threat to human health. To identify compounds, we screened the RIKEN natural product depository against representative isolates of four major fungal pathogens. This screen identified NPD6433, triazenyl indole broad-spectrum activity all screening strains, as well filamentous mold Aspergillus fumigatus. Mechanistic studies indicated that NPD6433 targets enoyl reductase domain fatty...
ClpXP is a two-component mitochondrial matrix protease. The caseinolytic peptidase chaperone subunit X (ClpX) recognizes and translocates protein substrates into the degradation chamber of protease P (ClpP) for proteolysis. degrades damaged respiratory chain proteins necessary cancer cell survival. Despite critical role in quality control, specific degrons, or modifications that tag substrate by human ClpXP, are still unknown. We demonstrated phosphorylated serine (pSer) targets to ClpX...
Lipid nanoparticles (LNPs) are widely used for delivering therapeutic nucleic acids, yet the relationship between their internal structure and intracellular behavior, particularly before RNA release, remains unclear. Here, we elucidate how lipid-siRNA organization within LNPs can modulate delivery dynamics. We use cryo-electron microscopy photochemical assays to reveal that increased siRNA loading reduce helper lipids' distribution LNP surface, while consistently localizes near surface....
Exchange proteins directly activated by cAMP (EPACs) are guanine nucleotide-exchange factors for the small GTPases Rap1 and Rap2 represent a key receptor ubiquitous second messenger in eukaryotes. The cAMP-dependent activation of apoEPAC is typically rationalized terms preexisting equilibrium between inactive active states. Structural mutagenesis analyses have shown that one critical determinants EPAC cluster salt bridges formed catalytic core helices alpha1 alpha2 at N terminus binding...
Conformational Exchange: Small GTPases, such as Ras and Rheb, exchange between major minor conformers when bound to GTP, with different functional properties for each state (see picture). Two-dimensional 15N CEST NMR spectroscopy is used quantify the parameters both Rheb complexed physiological GTP analogues GTPγS GppNHp. As a service our authors readers, this journal provides supporting information supplied by authors. Such materials are peer reviewed may be re-organized online delivery,...
Fatty acid synthase (FASN) catalyzes the de novo synthesis of palmitate, a 16-carbon chain fatty that is primary precursor lipid metabolism and an important intracellular signaling molecule. FASN attractive drug target in diabetes, cancer, liver diseases, viral infections. Here, we develop engineered full-length human (hFASN) enables isolation condensing modifying regions protein post-translation. The electron cryo-microscopy (cryoEM) structure determination core region hFASN to 2.7 Å...
A diverse antibody repertoire is essential for humoral immunity. Antibody diversification requires the introduction of deoxyuridine (dU) mutations within immunoglobulin genes to initiate somatic hypermutation (SHM) and class switch recombination (CSR). dUs are normally recognized excised by base excision repair (BER) protein uracil-DNA glycosylase 2 (UNG2). However, FAM72A downregulates UNG2 permitting persist trigger SHM CSR. How promotes degradation unknown. Here, we show that recruits a...
The Ras family of small GTPases control diverse signaling pathways through a conserved "switch" mechanism, which is turned on by binding GTP and off hydrolysis to GDP. Full understanding GTPase switch functions requires reliable, quantitative assays for nucleotide hydrolysis. Fluorescently labeled guanine nucleotides, such as 2'(3')-O-(N-methylanthraniloyl) (mant)-substituted GDP analogs, have been widely used investigate the molecular properties GTPases, including Rho. Using recently...
cAMP (adenosine 3',5'-cyclic monophosphate) is a ubiquitous second messenger that activates multitude of essential cellular responses. Two key receptors for in eukaryotes are protein kinase A (PKA) and the exchange directly activated by (EPAC), which recently discovered guanine nucleotide factor (GEF) small GTPases Rap1 Rap2. Previous attempts to investigate mechanism allosteric activation eukaryotic cAMP-binding domains (CBDs) at atomic or residue resolution have been hampered instability...
Abstract During fatty acid biosynthesis, acyl carrier proteins (ACPs) from type I fungal synthase (FAS) shuttle substrates and intermediates within a reaction chamber that hosts multiple spatially-fixed catalytic centers. A major challenge in understanding the mechanism of ACP-mediated substrate shuttling is experimental observation its transient interaction landscape chamber. Here, we have shown ACP spatial distribution sensitive to presence catalytically inhibited state, which enables...