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Kordus SL, Kroh HK, Rodríguez RC, Shrem RA, Peritore-Galve FC, Shupe JA, Wadzinski BE, Lacy DB, Spiller BW. Nanobodies against C. difficile TcdA and TcdB reveal unexpected neutralizing epitopes and provide a toolkit for toxin quantitation in vivo. PLoS Pathog 2023; 19:e1011496. [PMID: 37871122 PMCID: PMC10621975 DOI: 10.1371/journal.ppat.1011496] [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: 06/20/2023] [Revised: 11/02/2023] [Accepted: 10/07/2023] [Indexed: 10/25/2023] Open
Abstract
Clostridioides difficile is a leading cause of antibiotic-associated diarrhea and nosocomial infection in the United States. The symptoms of C. difficile infection (CDI) are associated with the production of two homologous protein toxins, TcdA and TcdB. The toxins are considered bona fide targets for clinical diagnosis as well as the development of novel prevention and therapeutic strategies. While there are extensive studies that document these efforts, there are several gaps in knowledge that could benefit from the creation of new research tools. First, we now appreciate that while TcdA sequences are conserved, TcdB sequences can vary across the span of circulating clinical isolates. An understanding of the TcdA and TcdB epitopes that drive broadly neutralizing antibody responses could advance the effort to identify safe and effective toxin-protein chimeras and fragments for vaccine development. Further, an understanding of TcdA and TcdB concentration changes in vivo can guide research into how host and microbiome-focused interventions affect the virulence potential of C. difficile. We have developed a panel of alpaca-derived nanobodies that bind specific structural and functional domains of TcdA and TcdB. We note that many of the potent neutralizers of TcdA bind epitopes within the delivery domain, a finding that could reflect roles of the delivery domain in receptor binding and/or the conserved role of pore-formation in the delivery of the toxin enzyme domains to the cytosol. In contrast, neutralizing epitopes for TcdB were found in multiple domains. The nanobodies were also used for the creation of sandwich ELISA assays that allow for quantitation of TcdA and/or TcdB in vitro and in the cecal and fecal contents of infected mice. We anticipate these reagents and assays will allow researchers to monitor the dynamics of TcdA and TcdB production over time, and the impact of various experimental interventions on toxin production in vivo.
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Affiliation(s)
- Shannon L. Kordus
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Heather K. Kroh
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Rubén Cano Rodríguez
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Rebecca A. Shrem
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - F. Christopher Peritore-Galve
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - John A. Shupe
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Brian E. Wadzinski
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
| | - Benjamin W. Spiller
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
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Kordus SL, Rodríguez RC, Krystofiak E, Loveridge N, Childress K, Borden Lacy D. Understanding the Roles of tcdE and tcdL During Toxin Secretion in Clostridioides difficile. Microsc Microanal 2023; 29:942. [PMID: 37613384 DOI: 10.1093/micmic/ozad067.469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Shannon L Kordus
- Department of Pathology, Microbiology, Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
- The Center for Structural Biology , Vanderbilt University, Nashville, TN, United States
| | - Rubén Cano Rodríguez
- Department of Pathology, Microbiology, Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
- The Center for Structural Biology , Vanderbilt University, Nashville, TN, United States
- Veterans Affairs, Nashville, TN, United States
| | - Evan Krystofiak
- Vanderbilt Cell Imaging Shared Resource Core, Vanderbilt University, Nashville, TN, United States
| | - Natalie Loveridge
- Department of Pathology, Microbiology, Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
- The Center for Structural Biology , Vanderbilt University, Nashville, TN, United States
| | - Kevin Childress
- Department of Pathology, Microbiology, Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
- The Center for Structural Biology , Vanderbilt University, Nashville, TN, United States
| | - D Borden Lacy
- Department of Pathology, Microbiology, Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
- The Center for Structural Biology , Vanderbilt University, Nashville, TN, United States
- Veterans Affairs, Nashville, TN, United States
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Abstract
Clostridioides difficile is a Gram-positive anaerobe that can cause a spectrum of disorders that range in severity from mild diarrhoea to fulminant colitis and/or death. The bacterium produces up to three toxins, which are considered the major virulence factors in C. difficile infection. These toxins promote inflammation, tissue damage and diarrhoea. In this Review, we highlight recent biochemical and structural advances in our understanding of the mechanisms that govern host-toxin interactions. Understanding how C. difficile toxins affect the host forms a foundation for developing novel strategies for treatment and prevention of C. difficile infection.
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Affiliation(s)
- Shannon L. Kordus
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - Audrey K. Thomas
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,The Veterans Affairs, Tennessee Valley Healthcare, System, Nashville, TN, USA,
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Howe MD, Kordus SL, Cole MS, Bauman AA, Aldrich CC, Baughn AD, Minato Y. Methionine Antagonizes para-Aminosalicylic Acid Activity via Affecting Folate Precursor Biosynthesis in Mycobacterium tuberculosis. Front Cell Infect Microbiol 2018; 8:399. [PMID: 30483484 PMCID: PMC6240602 DOI: 10.3389/fcimb.2018.00399] [Citation(s) in RCA: 12] [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: 05/13/2018] [Accepted: 10/23/2018] [Indexed: 12/23/2022] Open
Abstract
para-Aminosalicylic acid (PAS) is a second-line anti-tubercular drug that is used for the treatment of drug-resistant tuberculosis (TB). PAS efficacy in the treatment of TB is limited by its lower potency against Mycobacterium tuberculosis relative to many other drugs in the TB treatment arsenal. It is known that intrinsic metabolites, such as, para-aminobenzoic acid (PABA) and methionine, antagonize PAS and structurally related anti-folate drugs. While the basis for PABA-mediated antagonism of anti-folates is understood, the mechanism for methionine-based antagonism remains undefined. In the present study, we used both targeted and untargeted approaches to identify factors associated with methionine-mediated antagonism of PAS activity. We found that synthesis of folate precursors as well as a putative amino acid transporter, designated MetM, play crucial roles in this process. Disruption of metM by transposon insertion resulted in a ≥30-fold decrease in uptake of methionine in M. bovis BCG, indicating that metM is the major facilitator of methionine transport. We also discovered that intracellular biotin confers intrinsic PAS resistance in a methionine-independent manner. Collectively, our results demonstrate that methionine-mediated antagonism of anti-folate drugs occurs through sustained production of folate precursors.
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Affiliation(s)
- Michael D Howe
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Shannon L Kordus
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Malcolm S Cole
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, United States
| | - Allison A Bauman
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, United States
| | - Anthony D Baughn
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States
| | - Yusuke Minato
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, United States
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Abstract
The mechanism of action of para-aminosalicylic acid (PAS), a drug used to treat drug-resistant tuberculosis (TB), has been confirmed through the first synthesis and biochemical characterization of its active metabolite 7. The synthesis features the coupling of N2-acetyl-6-formylpterin obtained from the degradation of folic acid and appropriately functionalized arylamines to form Schiff bases. The sequential chemoselective reduction of the imine and pterin ring led to the formation of dihydrofolate analogue 7 and two other dihydropteroate species.
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Affiliation(s)
- Surendra Dawadi
- Department of Medicinal Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Shannon L Kordus
- Department of Microbiology and Immunology, University of Minnesota Medical School , Minneapolis, Minnesota 55455, United States
| | - Anthony D Baughn
- Department of Microbiology and Immunology, University of Minnesota Medical School , Minneapolis, Minnesota 55455, United States
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States
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