1
|
D’Antona AM, Lee JM, Zhang M, Friedman C, He T, Mosyak L, Bennett E, Lin L, Silverman M, Cometa F, Meade C, Hageman T, Sousa E, Cohen J, Marquette K, Ferguson D, Zhong X. Tyrosine Sulfation at Antibody Light Chain CDR-1 Increases Binding Affinity and Neutralization Potency to Interleukine-4. Int J Mol Sci 2024; 25:1931. [PMID: 38339208 PMCID: PMC10855961 DOI: 10.3390/ijms25031931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Structure and function of therapeutic antibodies can be modulated by a variety of post-translational modifications (PTM). Tyrosine (Tyr) sulfation is a type of negatively charged PTM that occurs during protein trafficking through the Golgi. In this study, we discovered that an anti-interleukin (IL)-4 human IgG1, produced by transiently transfected HEK293 cells, contained a fraction of unusual negatively charged species. Interestingly, the isolated acidic species exhibited a two-fold higher affinity to IL-4 and a nearly four-fold higher potency compared to the main species. Mass spectrometry (MS) showed the isolated acidic species possessed an +80-Dalton from the expected mass, suggesting an occurrence of Tyr sulfation. Consistent with this hypothesis, we show the ability to control the acidic species during transient expression with the addition of Tyr sulfation inhibitor sodium chlorate or, conversely, enriched the acidic species from 30% to 92% of the total antibody protein when the IL-4 IgG was co-transfected with tyrosylprotein sulfotransferase genes. Further MS and mutagenesis analysis identified a Tyr residue at the light chain complementarity-determining region-1 (CDRL-1), which was sulfated specifically. These results together have demonstrated for the first time that Tyr sulfation at CDRL-1 could modulate antibody binding affinity and potency to a human immune cytokine.
Collapse
Affiliation(s)
- Aaron M. D’Antona
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Julie M. Lee
- Translational Clinical Sciences, Pfizer Discovery & Early Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Melvin Zhang
- Inflammation and Immunology Research Unit, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Clarence Friedman
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Tao He
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Lidia Mosyak
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Eric Bennett
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Laura Lin
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Maddison Silverman
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Funi Cometa
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Caryl Meade
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Tyler Hageman
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Eric Sousa
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Justin Cohen
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Kimberly Marquette
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Darren Ferguson
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Xiaotian Zhong
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| |
Collapse
|
2
|
Zhou J, Yan GG, Cluckey D, Meade C, Ruth M, Sorm R, Tam AS, Lim S, Petridis C, Lin L, D’Antona AM, Zhong X. Exploring Parametric and Mechanistic Differences between Expi293F TM and ExpiCHO-S TM Cells for Transient Antibody Production Optimization. Antibodies (Basel) 2023; 12:53. [PMID: 37606437 PMCID: PMC10443273 DOI: 10.3390/antib12030053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 07/26/2023] [Accepted: 08/08/2023] [Indexed: 08/23/2023] Open
Abstract
Rapidly producing drug-like antibody therapeutics for lead molecule discovery and candidate optimization is typically accomplished by large-scale transient gene expression technologies (TGE) with cultivated mammalian cells. The TGE methodologies have been extensively developed over the past three decades, yet produce significantly lower yields than the stable cell line approach, facing the technical challenge of achieving universal high expression titers for a broad range of antibodies and therapeutics modalities. In this study, we explored various parameters for antibody production in the TGE cell host Expi293FTM and ExpiCHO-STM with the transfection reagents ExpiFectamineTM and polyethylenimine. We discovered that there are significant differences between Expi293FTM and ExpiCHO-STM cells with regards to DNA complex formation time and ratio, complex formation buffers, DNA complex uptake trafficking routes, responses to dimethyl sulfoxide and cell cycle inhibitors, as well as light-chain isotype expression preferences. This investigation mechanistically dissected the TGE processes and provided a new direction for future transient antibody production optimization.
Collapse
|
3
|
Zhong X, D’Antona AM. A potential antibody repertoire diversification mechanism through tyrosine sulfation for biotherapeutics engineering and production. Front Immunol 2022; 13:1072702. [PMID: 36569848 PMCID: PMC9774471 DOI: 10.3389/fimmu.2022.1072702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
The diversity of three hypervariable loops in antibody heavy chain and light chain, termed the complementarity-determining regions (CDRs), defines antibody's binding affinity and specificity owing to the direct contact between the CDRs and antigens. These CDR regions typically contain tyrosine (Tyr) residues that are known to engage in both nonpolar and pi stacking interaction with antigens through their complementary aromatic ring side chains. Nearly two decades ago, sulfotyrosine residue (sTyr), a negatively charged Tyr formed by Golgi-localized membrane-bound tyrosylprotein sulfotransferases during protein trafficking, were also found in the CDR regions and shown to play an important role in modulating antibody-antigen interaction. This breakthrough finding demonstrated that antibody repertoire could be further diversified through post-translational modifications, in addition to the conventional genetic recombination. This review article summarizes the current advances in the understanding of the Tyr-sulfation modification mechanism and its application in potentiating protein-protein interaction for antibody engineering and production. Challenges and opportunities are also discussed.
Collapse
|
4
|
Zhong X, D’Antona AM, Scarcelli JJ, Rouse JC. New Opportunities in Glycan Engineering for Therapeutic Proteins. Antibodies (Basel) 2022; 11:5. [PMID: 35076453 PMCID: PMC8788452 DOI: 10.3390/antib11010005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/22/2021] [Accepted: 12/31/2021] [Indexed: 11/17/2022] Open
Abstract
Glycans as sugar polymers are important metabolic, structural, and physiological regulators for cellular and biological functions. They are often classified as critical quality attributes to antibodies and recombinant fusion proteins, given their impacts on the efficacy and safety of biologics drugs. Recent reports on the conjugates of N-acetyl-galactosamine and mannose-6-phosphate for lysosomal degradation, Fab glycans for antibody diversification, as well as sialylation therapeutic modulations and O-linked applications, have been fueling the continued interest in glycoengineering. The current advancements of the human glycome and the development of a comprehensive network in glycosylation pathways have presented new opportunities in designing next-generation therapeutic proteins.
Collapse
Affiliation(s)
- Xiaotian Zhong
- BioMedicine Design, Medicinal Sciences, Pfizer Worldwide R&D, 610 Main Street, Cambridge, MA 02139, USA;
| | - Aaron M. D’Antona
- BioMedicine Design, Medicinal Sciences, Pfizer Worldwide R&D, 610 Main Street, Cambridge, MA 02139, USA;
| | - John J. Scarcelli
- BioProcess R&D, Biotherapeutics Pharmaceutical Sciences, Medicinal Sciences, Pfizer Worldwide R&D, 1 Burtt Road, Andover, MA 01810, USA;
| | - Jason C. Rouse
- Analytical R&D, Biotherapeutics Pharmaceutical Sciences, Medicinal Sciences, Pfizer Worldwide R&D, 1 Burtt Road, Andover, MA 01810, USA;
| |
Collapse
|
5
|
Zhong X, D’Antona AM. Recent Advances in the Molecular Design and Applications of Multispecific Biotherapeutics. Antibodies (Basel) 2021; 10:13. [PMID: 33808165 PMCID: PMC8103270 DOI: 10.3390/antib10020013] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/09/2021] [Accepted: 03/26/2021] [Indexed: 02/06/2023] Open
Abstract
Recombinant protein-based biotherapeutics drugs have transformed clinical pipelines of the biopharmaceutical industry since the launch of recombinant insulin nearly four decades ago. These biologic drugs are structurally more complex than small molecules, and yet share a similar principle for rational drug discovery and development: That is to start with a pre-defined target and follow with the functional modulation with a therapeutic agent. Despite these tremendous successes, this "one target one drug" paradigm has been challenged by complex disease mechanisms that involve multiple pathways and demand new therapeutic routes. A rapidly evolving wave of multispecific biotherapeutics is coming into focus. These new therapeutic drugs are able to engage two or more protein targets via distinct binding interfaces with or without the chemical conjugation to large or small molecules. They possess the potential to not only address disease intricacy but also exploit new therapeutic mechanisms and assess undruggable targets for conventional monospecific biologics. This review focuses on the recent advances in molecular design and applications of major classes of multispecific biotherapeutics drugs, which include immune cells engagers, antibody-drug conjugates, multispecific tetherbodies, biologic matchmakers, and small-scaffold multispecific modalities. Challenges posed by the multispecific biotherapeutics drugs and their future outlooks are also discussed.
Collapse
Affiliation(s)
- Xiaotian Zhong
- Department of BioMedicine Design, Medicinal Sciences, Pfizer Worldwide R&D, 610 Main Street, Cambridge, MA 02139, USA;
| | | |
Collapse
|
6
|
Root AR, Guntas G, Katragadda M, Apgar JR, Narula J, Chang CS, Hanscom S, McKenna M, Wade J, Meade C, Ma W, Guo Y, Liu Y, Duan W, Hendershot C, King AC, Zhang Y, Sousa E, Tam A, Benard S, Yang H, Kelleher K, Jin F, Piche-Nicholas N, Keating SE, Narciandi F, Lawrence-Henderson R, Arai M, Stochaj WR, Svenson K, Mosyak L, Lam K, Francis C, Marquette K, Wroblewska L, Zhu HL, Sheehan AD, LaVallie ER, D’Antona AM, Betts A, King L, Rosfjord E, Cunningham O, Lin L, Sapra P, Tchistiakova L, Mathur D, Bloom L. Discovery and optimization of a novel anti-GUCY2c x CD3 bispecific antibody for the treatment of solid tumors. MAbs 2021; 13:1850395. [PMID: 33459147 PMCID: PMC7833764 DOI: 10.1080/19420862.2020.1850395] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/26/2020] [Accepted: 11/10/2020] [Indexed: 12/29/2022] Open
Abstract
We report here the discovery and optimization of a novel T cell retargeting anti-GUCY2C x anti-CD3ε bispecific antibody for the treatment of solid tumors. Using a combination of hybridoma, phage display and rational design protein engineering, we have developed a fully humanized and manufacturable CD3 bispecific antibody that demonstrates favorable pharmacokinetic properties and potent in vivo efficacy. Anti-GUCY2C and anti-CD3ε antibodies derived from mouse hybridomas were first humanized into well-behaved human variable region frameworks with full retention of binding and T-cell mediated cytotoxic activity. To address potential manufacturability concerns, multiple approaches were taken in parallel to optimize and de-risk the two antibody variable regions. These approaches included structure-guided rational mutagenesis and phage display-based optimization, focusing on improving stability, reducing polyreactivity and self-association potential, removing chemical liabilities and proteolytic cleavage sites, and de-risking immunogenicity. Employing rapid library construction methods as well as automated phage display and high-throughput protein production workflows enabled efficient generation of an optimized bispecific antibody with desirable manufacturability properties, high stability, and low nonspecific binding. Proteolytic cleavage and deamidation in complementarity-determining regions were also successfully addressed. Collectively, these improvements translated to a molecule with potent single-agent in vivo efficacy in a tumor cell line adoptive transfer model and a cynomolgus monkey pharmacokinetic profile (half-life>4.5 days) suitable for clinical development. Clinical evaluation of PF-07062119 is ongoing.
Collapse
Affiliation(s)
- Adam R. Root
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | | | | | - Jatin Narula
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | - Sara Hanscom
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | - Jason Wade
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Caryl Meade
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Weijun Ma
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Yongjing Guo
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Yan Liu
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Weili Duan
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | - Amy C. King
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Yan Zhang
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Eric Sousa
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Amy Tam
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Susan Benard
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Han Yang
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | - Fang Jin
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | | | | | | | - Maya Arai
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | | | - Lidia Mosyak
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | | | | | | | | | - H. Lily Zhu
- BioMedicine Design, Pfizer Inc., Andover, MA, USA
| | | | | | | | - Alison Betts
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Lindsay King
- BioMedicine Design, Pfizer Inc., Andover, MA, USA
| | - Edward Rosfjord
- Oncology Research & Development, Pfizer Inc., Pearl River, NY, USA
| | | | - Laura Lin
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| | - Puja Sapra
- Oncology Research & Development, Pfizer Inc., Pearl River, NY, USA
| | | | - Divya Mathur
- Oncology Research & Development, Pfizer Inc., Pearl River, NY, USA
| | - Laird Bloom
- BioMedicine Design, Pfizer Inc., Cambridge, MA, USA
| |
Collapse
|
7
|
Apgar JR, Tam ASP, Sorm R, Moesta S, King AC, Yang H, Kelleher K, Murphy D, D’Antona AM, Yan G, Zhong X, Rodriguez L, Ma W, Ferguson DE, Carven GJ, Bennett EM, Lin L. Modeling and mitigation of high-concentration antibody viscosity through structure-based computer-aided protein design. PLoS One 2020; 15:e0232713. [PMID: 32379792 PMCID: PMC7205207 DOI: 10.1371/journal.pone.0232713] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 04/20/2020] [Indexed: 01/07/2023] Open
Abstract
For an antibody to be a successful therapeutic many competing factors require optimization, including binding affinity, biophysical characteristics, and immunogenicity risk. Additional constraints may arise from the need to formulate antibodies at high concentrations (>150 mg/ml) to enable subcutaneous dosing with reasonable volume (ideally <1.0 mL). Unfortunately, antibodies at high concentrations may exhibit high viscosities that place impractical constraints (such as multiple injections or large needle diameters) on delivery and impede efficient manufacturing. Here we describe the optimization of an anti-PDGF-BB antibody to reduce viscosity, enabling an increase in the formulated concentration from 80 mg/ml to greater than 160 mg/ml, while maintaining the binding affinity. We performed two rounds of structure guided rational design to optimize the surface electrostatic properties. Analysis of this set demonstrated that a net-positive charge change, and disruption of negative charge patches were associated with decreased viscosity, but the effect was greatly dependent on the local surface environment. Our work here provides a comprehensive study exploring a wide sampling of charge-changes in the Fv and CDR regions along with targeting multiple negative charge patches. In total, we generated viscosity measurements for 40 unique antibody variants with full sequence information which provides a significantly larger and more complete dataset than has previously been reported.
Collapse
Affiliation(s)
- James R. Apgar
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
- * E-mail:
| | - Amy S. P. Tam
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Rhady Sorm
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Sybille Moesta
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Amy C. King
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Han Yang
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Kerry Kelleher
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Denise Murphy
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Aaron M. D’Antona
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Guoying Yan
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Xiaotian Zhong
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Linette Rodriguez
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Weijun Ma
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Darren E. Ferguson
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Gregory J. Carven
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Eric M. Bennett
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| | - Laura Lin
- BioMedicine Design, Pfizer Inc, Cambridge, Massachusetts, United States of America
| |
Collapse
|
8
|
Ferguson DE, Mahan ER, Ma W, Bitzas G, Zhong X, Zollner R, D’Antona AM. Parallel loading and complete automation of a 3-step mAb purification process for multiple samples using a customized preparative chromatography instrument with networked pumps. J Chromatogr A 2018; 1542:50-60. [DOI: 10.1016/j.chroma.2018.02.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 02/06/2018] [Accepted: 02/09/2018] [Indexed: 11/26/2022]
|
9
|
D’Antona AM, Ahn KH, Wang L, Mierke DF, Lucas-Lenard J, Kendall DA. A cannabinoid receptor 1 mutation proximal to the DRY motif results in constitutive activity and reveals intramolecular interactions involved in receptor activation. Brain Res 2006; 1108:1-11. [PMID: 16879811 PMCID: PMC2733829 DOI: 10.1016/j.brainres.2006.05.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Revised: 05/04/2006] [Accepted: 05/06/2006] [Indexed: 11/25/2022]
Abstract
Activation of a G-protein-coupled receptor involves changes in specific microdomain interactions within the transmembrane region of the receptor. Here, we have focused on the role of L207, proximal to the DRY motif of the human cannabinoid receptor 1 in the interconversion of the receptor resting and active states. Ligand binding analysis of the mutant receptor L207A revealed an enhanced affinity for agonists (three- to six-fold) and a diminished affinity for inverse agonists (19- to 35-fold) compared to the wild-type receptor, properties characteristic of constitutive activity. To further examine whether this mutant adopts a ligand-independent, active form, treatment with GTPgammaS was used to inhibit G protein coupling. Under these conditions, the L207A receptor exhibited a 10-fold increase in affinity for the inverse agonist SR141716A, consistent with a shift away from an enhanced precoupled state. Analysis of the cellular activity of the L207A receptor showed elevated basal cyclic AMP accumulation relative to the wild type that is inhibited by SR141716A, consistent with receptor-mediated Gs precoupling. Using toxins to selectively abrogate Gs or Gi coupling, we found that CP55940 nonetheless induced only a Gi response suggesting a strong preference of this ligand-bound form for Gi in this system. Molecular dynamics simulations reveal that the single residue change of L207A impacts the association of TM3 and TM6 in the receptor by altering hydrophobic interactions involving L207, the salt bridge involving the Arg of the DRY motif, and the helical structure of TM6, consistent with events leading to activation. The structural alterations parallel those observed in models of a mutant CB(1) receptor T210I, with established constitutive activity (D'Antona, A.M., Ahn, K.H. and Kendall, D.A., 2006. Mutations of CB1 T210 produce active and inactive receptor forms: correlations with ligand affinity, receptor stability, and cellular localization. Biochemistry, 45, 5606-5617).
Collapse
Affiliation(s)
- Aaron M. D’Antona
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Kwang H. Ahn
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Lei Wang
- Department of Chemistry and Department of Molecular Pharmacology, Brown University, Providence, RI 02912, USA
| | - Dale F. Mierke
- Department of Chemistry and Department of Molecular Pharmacology, Brown University, Providence, RI 02912, USA
| | - Jean Lucas-Lenard
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Debra A. Kendall
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
- Corresponding author. E-mail address: (D.A. Kendall)
| |
Collapse
|