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Martin P, Kurth EA, Budean D, Momplaisir N, Qu E, Simien JM, Orellana GE, Brautigam CA, Smrcka AV, Haglund E. Biophysical characterization of the CXC chemokine receptor 2 ligands. PLoS One 2024; 19:e0298418. [PMID: 38625857 PMCID: PMC11020491 DOI: 10.1371/journal.pone.0298418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 10/09/2023] [Accepted: 01/24/2024] [Indexed: 04/18/2024] Open
Abstract
The chemokines of the immune system act as first responders by operating as chemoattractants, directing immune cells to specific locations of inflamed tissues. This promiscuous network is comprised of 50 ligands and 18 receptors where the ligands may interact with the receptors in various oligomeric states i.e., monomers, homodimers, and heterodimers. Chemokine receptors are G-protein coupled receptors (GPCRs) present in the membrane of immune cells. The migration of immune cells occurs in response to a concentration gradient of the ligands. Chemotaxis of neutrophils is directed by CXC-ligand (CXCL) activation of the membrane bound CXC chemokine receptor 2 (CXCR2). CXCR2 plays an important role in human health and is linked to disorders such as autoimmune disorders, inflammation, and cancer. Yet, despite their important role, little is known about the biophysical characteristics controlling ligand:ligand and ligand:receptor interaction essential for biological activity. In this work, we study the homodimers of three of the CXCR2 cognate ligands, CXCL1, CXCL5, and CXCL8. The ligands share high structural integrity but a low sequence identity. We show that the sequence diversity has evolved different binding affinities and stabilities for the CXC-ligands resulting in diverse agonist/antagonist behavior. Furthermore, CXC-ligands fold through a three-state mechanism, populating a folded monomeric state before associating into an active dimer.
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Affiliation(s)
- Patrick Martin
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Emily A. Kurth
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - David Budean
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Nathalie Momplaisir
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Elaine Qu
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Jennifer M. Simien
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Grace E. Orellana
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Chad A. Brautigam
- Department of Biophysics and the Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Alan V. Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Ellinor Haglund
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
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Simien JM, Orellana GE, Phan HTN, Hu Y, Kurth EA, Ruf C, Kricek F, Wang Q, Smrcka AV, Haglund E. A Small Contribution to a Large System: The Leptin Receptor Complex. J Phys Chem B 2023; 127:2457-2465. [PMID: 36912891 DOI: 10.1021/acs.jpcb.3c01090] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Obesity is a classified epidemic, increasing the risk of secondary diseases such as diabetes, inflammation, cardiovascular disease, and cancer. The pleiotropic hormone leptin is the proposed link for the gut-brain axis controlling nutritional status and energy expenditure. Research into leptin signaling provides great promise toward discovering therapeutics for obesity and its related diseases targeting leptin and its cognate leptin receptor (LEP-R). The molecular basis underlying the human leptin receptor complex assembly remains obscure, due to the lack of structural information regarding the biologically active complex. In this work, we investigate the proposed receptor binding sites in human leptin utilizing designed antagonist proteins combined with AlphaFold predictions. Our results show that binding site I has a more intricate role in the active signaling complex than previously described. We hypothesize that the hydrophobic patch in this region engages a third receptor forming a higher-order complex, or a new LEP-R binding site inducing allosteric rearrangement.
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Affiliation(s)
- Jennifer M Simien
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Grace E Orellana
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Hoa T N Phan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Yao Hu
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Emily A Kurth
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Christine Ruf
- NBS-C BioScience & Consulting GmbH, Vienna, 1230, Austria
| | - Franz Kricek
- NBS-C BioScience & Consulting GmbH, Vienna, 1230, Austria
| | - Qian Wang
- Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Ellinor Haglund
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
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