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Bérouti M, Lammens K, Heiss M, Hansbauer L, Bauernfried S, Stöckl J, Pinci F, Piseddu I, Greulich W, Wang M, Jung C, Fröhlich T, Carell T, Hopfner KP, Hornung V. Lysosomal endonuclease RNase T2 and PLD exonucleases cooperatively generate RNA ligands for TLR7 activation. Immunity 2024:S1074-7613(24)00215-2. [PMID: 38697119 DOI: 10.1016/j.immuni.2024.04.010] [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: 10/16/2023] [Revised: 03/06/2024] [Accepted: 04/12/2024] [Indexed: 05/04/2024]
Abstract
Toll-like receptor 7 (TLR7) is essential for recognition of RNA viruses and initiation of antiviral immunity. TLR7 contains two ligand-binding pockets that recognize different RNA degradation products: pocket 1 recognizes guanosine, while pocket 2 coordinates pyrimidine-rich RNA fragments. We found that the endonuclease RNase T2, along with 5' exonucleases PLD3 and PLD4, collaboratively generate the ligands for TLR7. Specifically, RNase T2 generated guanosine 2',3'-cyclic monophosphate-terminated RNA fragments. PLD exonuclease activity further released the terminal 2',3'-cyclic guanosine monophosphate (2',3'-cGMP) to engage pocket 1 and was also needed to generate RNA fragments for pocket 2. Loss-of-function studies in cell lines and primary cells confirmed the critical requirement for PLD activity. Biochemical and structural studies showed that PLD enzymes form homodimers with two ligand-binding sites important for activity. Previously identified disease-associated PLD mutants failed to form stable dimers. Together, our data provide a mechanistic basis for the detection of RNA fragments by TLR7.
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Affiliation(s)
- Marleen Bérouti
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Katja Lammens
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Matthias Heiss
- Department of Chemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Larissa Hansbauer
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Stefan Bauernfried
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Jan Stöckl
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Francesca Pinci
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Ignazio Piseddu
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany; Department of Medicine II, University Hospital Munich, Munich, Germany
| | - Wilhelm Greulich
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Meiyue Wang
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Christophe Jung
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Thomas Fröhlich
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Thomas Carell
- Department of Chemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Karl-Peter Hopfner
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany
| | - Veit Hornung
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität, Munich, Germany.
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Yuan M, Peng L, Huang D, Gavin A, Luan F, Tran J, Feng Z, Zhu X, Matteson J, Wilson IA, Nemazee D. Structural and mechanistic insights into disease-associated endolysosomal exonucleases PLD3 and PLD4. Structure 2024:S0969-2126(24)00079-0. [PMID: 38537643 DOI: 10.1016/j.str.2024.02.019] [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: 12/04/2023] [Revised: 02/12/2024] [Accepted: 02/29/2024] [Indexed: 04/09/2024]
Abstract
Endolysosomal exonucleases PLD3 and PLD4 (phospholipases D3 and D4) are associated with autoinflammatory and autoimmune diseases. We report structures of these enzymes, and the molecular basis of their catalysis. The structures reveal an intra-chain dimer topology forming a basic active site at the interface. Like other PLD superfamily members, PLD3 and PLD4 carry HxKxxxxD/E motifs and participate in phosphodiester-bond cleavage. The enzymes digest ssDNA and ssRNA in a 5'-to-3' manner and are blocked by 5'-phosphorylation. We captured structures in apo, intermediate, and product states and revealed a "link-and-release" two-step catalysis. We also unexpectedly demonstrated phosphatase activity via a covalent 3-phosphohistidine intermediate. PLD4 contains an extra hydrophobic clamp that stabilizes substrate and could affect oligonucleotide substrate preference and product release. Biochemical and structural analysis of disease-associated mutants of PLD3/4 demonstrated reduced enzyme activity or thermostability and the possible basis for disease association. Furthermore, these findings provide insight into therapeutic design.
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Affiliation(s)
- Meng Yuan
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Linghang Peng
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Deli Huang
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Amanda Gavin
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Fangkun Luan
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jenny Tran
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ziqi Feng
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Xueyong Zhu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jeanne Matteson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - David Nemazee
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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Lee JC, Shirey RJ, Turner LD, Park H, Lairson LL, Janda KD. Discovery of PLD4 modulators by high-throughput screening and kinetic analysis. Results Chem 2024; 7:101349. [PMID: 38560090 PMCID: PMC10977906 DOI: 10.1016/j.rechem.2024.101349] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024] Open
Abstract
Phospholipase D3 (PLD3) and D4 (PLD4) are endolysosomal exonucleases of ssDNA and ssRNA that regulate innate immunity. Polymorphisms of these enzymes are correlated with numerous human diseases, including Alzheimer's, rheumatoid arthritis, and systemic sclerosis. Pharmacological modulation of these immunoregulatory proteins may yield novel immunotherapies and adjuvants. A previous study reported a high-throughput screen (N = 17,952) that discovered a PLD3-selective activator and inhibitor, as well as a nonselective inhibitor, but failed to identify selective modulators of PLD4. However, modulators selective for PLD4 are therapeutically pertinent, since recent reports have shown that regulating this protein has direct implications in cancer and autoimmune diseases. Furthermore, the high expression of PLD4 in dendritic and myeloid cells, in comparison to the broader expression of PLD3, presents the opportunity for a cell-targeted immunotherapy. Here, we describe screening of an expended diversity library (N = 45,760) with an improved platform and report the discovery of one inhibitor and three activators selective for PLD4. Furthermore, kinetic modeling and structural analysis suggest mechanistic differences in the modulation of these hits. These findings further establish the utility of this screening platform and provide a set of chemical scaffolds to guide future small-molecule development for this novel immunoregulator target.
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Affiliation(s)
- Jinny Claire Lee
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ryan J. Shirey
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lewis D. Turner
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Hyeri Park
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Luke L. Lairson
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Kim D. Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Shirey RJ, Turner LD, Lairson LL, Janda KD. Modulators of immunoregulatory exonucleases PLD3 and PLD4 identified by high-throughput screen. Bioorg Med Chem Lett 2021; 49:128293. [PMID: 34332037 DOI: 10.1016/j.bmcl.2021.128293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 06/09/2021] [Revised: 07/22/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
PLD3 and PLD4 have recently been revealed to be endosomal exonucleases that regulate the innate immune response by digesting the ligands of nucleic acid sensors. These enzymes can suppress RNA and DNA innate immune sensors like toll-like receptor 9, and PLD4-deficent mice exhibit inflammatory disease. Targeting these immunoregulatory enzymes presents an opportunity to indirectly regulate innate immune nucleic acid sensors that could yield immunotherapies, adjuvants, and nucleic acid drug stabilizers. To aid in delineating the therapeutic potential of these targets, we have developed a high-throughput fluorescence enzymatic assay to identify modulators of PLD3 and PLD4. Screening of a diversity library (N = 17952) yielded preferential inhibitors of PLD3 and PLD4 in addition to a PLD3 selective activator. The modulation models of these compounds were delineated by kinetic analysis. This work presents an inexpensive and simple method to identify modulators of these immunoregulatory exonucleases.
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Affiliation(s)
- Ryan J Shirey
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Lewis D Turner
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Luke L Lairson
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, United States
| | - Kim D Janda
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, United States.
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Cappel C, Gonzalez AC, Damme M. Quantification and characterization of the 5' exonuclease activity of the lysosomal nuclease PLD3 by a novel cell-based assay. J Biol Chem 2020; 296:100152. [PMID: 33288674 PMCID: PMC7857491 DOI: 10.1074/jbc.ra120.015867] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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: 09/02/2020] [Revised: 12/01/2020] [Accepted: 12/06/2020] [Indexed: 01/09/2023] Open
Abstract
Phospholipase D3 (PLD3) and phospholipase D4 (PLD4), the most recently described lysosomal nucleases, are associated with Alzheimer’s disease, spinocerebellar ataxia, and systemic lupus erythematosus. They exhibit 5′ exonuclease activity on single-stranded DNA, hydrolyzing it at the acidic pH associated with the lysosome. However, their full cellular function is inadequately understood. To examine these enzymes, we developed a robust and automatable cell-based assay based on fluorophore- and fluorescence-quencher-coupled oligonucleotides for the quantitative determination of acidic 5′ exonuclease activity. We validated the assay under knockout and PLD-overexpression conditions and then applied it to characterize PLD3 and PLD4 biochemically. Our experiments revealed PLD3 as the principal acid 5′ exonuclease in HeLa cells, where it showed a markedly higher specific activity compared with PLD4. We further used our newly developed assay to determine the substrate specificity and inhibitory profile of PLD3 and found that proteolytic processing of PLD3 is dispensable for its hydrolytic activity. We followed the expression, proteolytic processing, and intracellular distribution of genetic PLD3 variants previously associated with Alzheimer’s disease and investigated each variant's effect on the 5′ nuclease activity of PLD3, finding that some variants lead to reduced activity, but others not. The development of a PLD3/4-specific biochemical assay will be instrumental in understanding better both nucleases and their incompletely understood roles in vitro and in vivo.
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Affiliation(s)
- Cedric Cappel
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | | | - Markus Damme
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany.
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Langenmayer MC, Jung S, Majzoub-Altweck M, Trefz FM, Seifert C, Knubben-Schweizer G, Fries R, Hermanns W, Gollnick NS. Zinc Deficiency-Like Syndrome in Fleckvieh Calves: Clinical and Pathological Findings and Differentiation from Bovine Hereditary Zinc Deficiency. J Vet Intern Med 2018; 32:853-859. [PMID: 29424482 PMCID: PMC5866964 DOI: 10.1111/jvim.15040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [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: 07/19/2017] [Revised: 11/17/2017] [Accepted: 12/14/2017] [Indexed: 12/17/2022] Open
Abstract
Background Zinc deficiency‐like (ZDL) syndrome is an inherited defect of Fleckvieh calves, with striking similarity to bovine hereditary zinc deficiency (BHZD). However, the causative mutation in a phospholipase D4 encoding gene (PLD4) shows no connection to zinc metabolism. Objectives To describe clinical signs, laboratory variables, and pathological findings of ZDL syndrome and their utility to differentiate ZDL from BHZD and infectious diseases with similar phenotype. Animals Nine hospitalized calves with crusting dermatitis and confirmed mutation in PLD4 and medical records from 25 calves with crusting dermatitis or suspected zinc deficiency. Methods Prospective and retrospective case series. Results The 9 calves (age: 5–53 weeks) displayed a moderate to severe crusting dermatitis mainly on the head, ventrum, and joints. Respiratory and digestive tract inflammations were frequently observed. Zinc supplementation did not lead to remission of clinical signs in 4 calves. Laboratory variables revealed slight anemia in 8 calves, hypoalbuminemia in 6 calves, but reduced serum zinc concentrations in only 3 calves. Mucosal erosions/ulcerations were present in 7 calves and thymus atrophy or reduced thymic weights in 8 calves. Histologically, skin lesions were indistinguishable from BHZD. Retrospective analysis of medical records revealed the presence of this phenotype since 1988 and pedigree analysis revealed a common ancestor of several affected calves. Conclusions and Clinical Importance ZDL syndrome should be suspected in Fleckvieh calves with crusting dermatitis together with diarrhea or respiratory tract inflammations without response to oral zinc supplementation. Definite diagnosis requires molecular genetic confirmation of the PLD4 mutation.
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Affiliation(s)
- M C Langenmayer
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, LMU Munich, Munich, Germany.,Institute for Infectious Diseases and Zoonoses, LMU Munich, Munich, Germany
| | - S Jung
- Chair of Animal Breeding, Technische Universität München, Freising-Weihenstephan, Germany
| | - M Majzoub-Altweck
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, LMU Munich, Munich, Germany
| | - F M Trefz
- Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleißheim, Germany
| | - C Seifert
- Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleißheim, Germany
| | - G Knubben-Schweizer
- Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleißheim, Germany
| | - R Fries
- Chair of Animal Breeding, Technische Universität München, Freising-Weihenstephan, Germany
| | - W Hermanns
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, LMU Munich, Munich, Germany
| | - N S Gollnick
- Clinic for Ruminants with Ambulatory and Herd Health Services at the Centre for Clinical Veterinary Medicine, LMU Munich, Oberschleißheim, Germany
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