title: The peptide-binding cavity is essential for Als3-mediated adhesion of Candida albicans to human cells.
abstract: The adhesive phenotype of Candida albicans contributes to its ability to colonize the host and cause disease. Als proteins are one of the most widely studied C. albicans virulence attributes; deletion of ALS3 produces the greatest reduction in adhesive function. Although adhesive activity is thought to reside within the N-terminal domain of Als proteins (NT-Als), the molecular mechanism of adhesion remains unclear. We designed mutations in NT-Als3 that test the contribution of the peptide-binding cavity (PBC) to C. albicans adhesion and assessed the adhesive properties of other NT-Als3 features in the absence of a functional PBC. Structural analysis of purified loss-of-PBC-function mutant proteins showed that the mutations did not alter the overall structure or surface properties of NT-Als3. The mutations were incorporated into full-length ALS3 and integrated into the ALS3 locus of a deletion mutant, under control of the native ALS3 promoter. The PBC mutant phenotype was evaluated in assays using monolayers of human pharyngeal epithelial and umbilical vein endothelial cells, and freshly collected human buccal epithelial cells in suspension. Loss of PBC function resulted in an adhesion phenotype that was indistinguishable from the Δals3/Δals3 strain. The adhesive contribution of the Als3 amyloid-forming-region (AFR) was also tested using these methods. C. albicans strains producing cell surface Als3 in which the amyloidogenic potential was destroyed showed little contribution of the AFR to adhesion, instead suggesting an aggregative function for the AFR. Collectively, these results demonstrate the essential and principal role of the PBC in Als3 adhesion.
authors.affiliation: From the Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington SW7 2AZ, United Kingdom.
authors.forename: Jing
authors.initials: J
authors.lastname: Lin
authors.affiliation: the Department of Pathobiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61802, and.
authors.forename: Soon-Hwan
authors.initials: SH
authors.lastname: Oh
authors.affiliation: From the Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington SW7 2AZ, United Kingdom.
authors.forename: Rhian
authors.initials: R
authors.lastname: Jones
authors.affiliation: From the Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington SW7 2AZ, United Kingdom.
authors.forename: James A
authors.initials: JA
authors.lastname: Garnett
authors.affiliation: the Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom.
authors.forename: Paula S
authors.initials: PS
authors.lastname: Salgado
authors.affiliation: From the Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington SW7 2AZ, United Kingdom.
authors.forename: Sophia
authors.initials: S
authors.lastname: Rusnakova
authors.affiliation: From the Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington SW7 2AZ, United Kingdom.
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Matthews
authors.affiliation: the Department of Pathobiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61802, and lhoyer@illinois.edu.
authors.forename: Lois L
authors.initials: LL
authors.lastname: Hoyer
authors.affiliation: From the Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington SW7 2AZ, United Kingdom, e.cota@imperial.ac.uk.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Cota
mesh_terms: D002176:Candida albicans / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002177:Candidiasis / Q000382:microbiology*; D018360:Crystallography, X-Ray; D042783:Endothelial Cells / Q000382:microbiology; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D017434:Protein Structure, Tertiary
chemical_list: C113620:ALS3 protein, Candida albicans; D005656:Fungal Proteins
keywords: Adhesion; Aggregation; Als Adhesins; Candida albicans; Functional Amyloid; Nuclear Magnetic Resonance (NMR); Peptide-binding Cavity; Peptide-binding Protein; X-ray Crystallography