John Tesmer
Title:
Walther Distinguished Professor of Cancer Structural Biology
PhD Granting Institution:
Purdue
Contact:
Email Address: jtesmer@purdue.edu
Office Phone: 765-494-1807
Lab Website Link: https://www.bio.purdue.edu/lab/tesmer/
Primary Training Group:
Biomolecular Structure and Biophysics
Secondary Training Groups:
Cancer Biology
Research Areas:
Biophysical studies of GPCR signaling pathways using X-ray crystallography, single particle cryo-EM, and HDX-MS. A key focus has been the structure and function of GPCR kinases (GRKs).
Current Projects:
Molecular Basis of Heterotrimeric G Protein Function Signal transduction conveyed from G protein-coupled receptors (GPCRs) via heterotrimeric G proteins is one of the classic paradigms of hormone action, wherein extracellular signals lead not only to transient changes in the concentrations of intracellular second messengers but also to sustained changes such as chemotaxis, cell growth, and metastasis. As a post-doctoral fellow with Stephen Sprang, I determined the atomic structure of the RGS4-Gαi1 complex (Tesmer et al. Cell 1997), the first of a regulator of G protein signaling (RGS) protein and of an RGS protein in complex with a Gα subunit. I followed this with crystal structures of Gαs alone (Sunahara et al. Science 1997) and bound to the catalytic domains of adenylyl cyclase (Tesmer et al. Science 1997; Tesmer et al. Science 1999), the first of a Gα-effector enzyme complex. As an independent investigator, my lab has focused on effector enzymes responsive to Gβγ (Yen et al. NSMB 2024; Chen et al. NSMB 2024), which are key regulators of cardiovascular function and cell growth/transformation. Current projects in the lab include investigating how Gβγ subunits regulate full-length mammalian adenylyl cyclase 5. Structure and Function of G Protein-Coupled Receptor Kinases (GRKs) The ~800 GPCRs in the human genome are regulated by a family of seven kinases that inhibit signaling by activated GPCRs, ensuring a return to homeostasis. In 2003, my lab published the structure of the GRK2-Gβγ complex, the first of a GRK and the first of Gβγ subunits in complex with an effector (Lodowski et al. Science 2003). In 2005, the lab reported the structure of the Gαq-GRK2-Gβγ complex (Tesmer et al. 2005), providing a snapshot of activated Gα and Gβγ subunits at the membrane as they engage a common target. The work also yielded the first atomic structure of Gαq. The lab went on to characterize GRKs from other subfamilies: GRK6, GRK1 (rhodopsin kinase), and GRK5. These structures helped to identify sites that form the docking site for activated GPCRs and anionic phospholipids. Recently, we determined the cryo-EM structure of the rhodopsin–GRK1 (rhodopsin kinase) complex, the first of a GPCR engaged by a GRK (Chen et al. Nature 2021). Current efforts are directed towards determining structures of rhodopsin and ACKR3 with other GRKs to refine our models of how GRK selectivity for receptors is achieved. To this end, we have determined the structures of a series of agonist bound complexes of ACKR3 (Yen et al. Sci Adv. 2022) and have defined the molecular consequences of differential phosphorylation barcoding on arrestin configuration by different GRK subfamilies using cryo-EM (Chen et al. Nature 2025). GPCR-Linked Rho Guanine Nucleotide Exchange Factors (RhoGEFs) Sustained changes in cell behavior induced by GPCRs typically involve modulating the actin cytoskeleton and gene transcription via RhoGEFs. These enzymes play a central role in chemotaxis, tumor growth and metastasis by activating various members of the Rho GTPase family. In 2004, my lab reported atomic structures of the catalytic domains of leukemia-associated RhoGEF (LARG) alone and in complex with RhoA (Kristelly et al. JBC 2004), and in 2006, the structures of the oncogenic Gα12 and Gα13 subunits that regulate the activity of LARG and closely related RhoGEFs (Kreutz et al. Biochemistry 2006). In 2007, the lab resolved the structure of the Gαq-p63RhoGEF-RhoA ternary complex, capturing a snapshot of a novel Gαq signaling pathway implicated in the development of cardiac hypertrophy (Lutz et al. Science 2007). More recently, we have been characterizing the Rac1 specific enzyme, P-Rex1, a Gβγ-regulated RhoGEF that plays a key role in neutrophil function and in metastasis of breast and prostate cancer (Ravala et al. eLife 2024), and Trio (Bandekar Sci. Signaling 2019), a close relative of p63RhoGEF responsible for tumor growth in uveal melanoma. Identification and Rational Design of Small Molecule Probes We also use biophysics to accelerate the discovery of selective small molecule agents that can be used to probe the above signaling cascades in more physiological contexts, or that can serve as leads for drug development. Our most advanced work in this realm involves GRK inhibitors. GRK2 subfamily inhibitors have potential applications ranging from treatment of congestive heart failure to inhibition of arterial and renal plaque formation. GRK5 subfamily inhibitors are expected to have utility in treatment of cardiac hypertrophy and cancer. In 2012, we identified the selective serotonin re-uptake inhibitor paroxetine (Paxil) as a selective GRK2/3 inhibitor, which was later shown to reverse heart malfunction in mice subjected to infarction (Schumacher et al. 2015) and modified this to have higher potency and efficacy in animal models (Roy et al. 2025).
Importance of Interdisciplinary Research:
As a structural biology lab, we have always valued meaningful collaborations with medicinal chemists, pharmacologists, and cell biologists to test our mechanistic hypotheses under as physiological conditions as possible.