Variations in candidalysin amino acid sequence influence toxicity and host responses
Don N. Wickramasinghe,
Claire M. Lyon,
Sejeong Lee,
Olivia W. Hepworth,
Emily L. Priest,
Corinne Maufrais,
Adam P. Ryan,
Emmanuelle Permal,
Derek Sullivan,
Brenda A. McManus,
Bernhard Hube,
Geraldine Butler,
Christophe d'Enfert,
Julian R. Naglik,
Jonathan P. Richardson
Affiliations
Don N. Wickramasinghe
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
Claire M. Lyon
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
Sejeong Lee
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
Olivia W. Hepworth
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
Emily L. Priest
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
Corinne Maufrais
Institut Pasteur, Université Paris Cité, INRAe USC 2019, Unité Biologie et Pathogénicité Fongiques, Paris, France
Adam P. Ryan
School of Biomedical and Biomolecular Science and UCD Conway Institute of Biomolecular and Biomedical Research, Conway Institute, University College Dublin, Dublin, Ireland
Emmanuelle Permal
Institut Pasteur, Université Paris Cité, INRAe USC 2019, Unité Biologie et Pathogénicité Fongiques, Paris, France
Derek Sullivan
Division of Oral Biosciences, Dublin Dental University Hospital, and School of Dental Science, Trinity College Dublin, Dublin, Ireland
Brenda A. McManus
Division of Oral Biosciences, Dublin Dental University Hospital, and School of Dental Science, Trinity College Dublin, Dublin, Ireland
Bernhard Hube
Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoll Institute (HKI), Jena, Germany
Geraldine Butler
School of Biomedical and Biomolecular Science and UCD Conway Institute of Biomolecular and Biomedical Research, Conway Institute, University College Dublin, Dublin, Ireland
Christophe d'Enfert
Institut Pasteur, Université Paris Cité, INRAe USC 2019, Unité Biologie et Pathogénicité Fongiques, Paris, France
Julian R. Naglik
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
Jonathan P. Richardson
Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, United Kingdom
ABSTRACT Candida albicans causes millions of mucosal infections in humans annually. Hyphal overgrowth on mucosal surfaces is frequently associated with tissue damage caused by candidalysin, a secreted peptide toxin that destabilizes the plasma membrane of host cells thereby promoting disease and immunopathology. Candidalysin was first identified in C. albicans strain SC5314, but recent investigations have revealed candidalysin “variants” of differing amino acid sequence in isolates of C. albicans, and the related species C. dubliniensis, and C tropicalis, suggesting that sequence variation among candidalysins may be widespread in natural populations of these Candida species. Here, we analyzed ECE1 gene sequences from 182 C. albicans isolates, 10 C. dubliniensis isolates, and 78 C. tropicalis isolates and identified 10, 3, and 2 candidalysin variants in these species, respectively. Application of candidalysin variants to epithelial cells revealed differences in the ability to cause cellular damage, changes in metabolic activity, calcium influx, MAPK signalling, and cytokine secretion, while biophysical analyses indicated that variants exhibited differences in their ability to interact with and permeabilize a membrane. This study identifies candidalysin variants with differences in biological activity that are present in medically relevant Candida species.IMPORTANCEFungal infections are a significant burden to health. Candidalysin is a toxin produced by Candida albicans that damages host tissues, facilitating infection. Previously, we demonstrated that candidalysins exist in the related species C. dubliniensis and C. tropicalis, thereby identifying these molecules as a toxin family. Recent genomic analyses have highlighted the presence of a small number of candidalysin “variant” toxins, which have different amino acid sequences to those originally identified. Here, we screened genome sequences of isolates of C. albicans, C. dubliniensis, and C. tropicalis and identified candidalysin variants in all three species. When applied to epithelial cells, candidalysin variants differed in their ability to cause damage, activate intracellular signaling pathways, and induce innate immune responses, while biophysical analysis revealed differences in the ability of candidalysin variants to interact with lipid bilayers. These findings suggest that intraspecies variation in candidalysin amino acid sequence may influence fungal pathogenicity.
