title: Pga13 in Candida albicans is localized in the cell wall and influences cell surface properties, morphogenesis and virulence.
abstract: The fungal cell wall is an essential organelle required for maintaining cell integrity and also plays an important role in the primary interactions between pathogenic fungi and their hosts. PGA13 encodes a GPI protein in the human pathogen Candida albicans, which is highly up-regulated during cell wall regeneration in protoplasts. The Pga13 protein contains a unique tandem repeat, which is present five times and is characterized by conserved spacing between the four cysteine residues. Furthermore, the mature protein contains 38% serine and threonine residues, and therefore probably is a highly glycosylated cell wall protein. Consistent with this, a chimeric Pga13-V5 protein could be localized to the cell wall, but only after deglycosylation was performed. Disruption of PGA13 led to increased sensitivity to Congo red, Calcofluor white, and zymolyase, and to a diminished ability of protoplasts to recover their cell wall. In addition, pga13Δ mutants exhibited delayed filamentation, a higher surface hydrophobicity, and increased adherence and flocculation (cell-cell interactions). Furthermore, transcript profiling showed that expression of four members of the ALS family (adhesin-encoding genes) is up-regulated in the pga13Δ null mutant. Altogether, these results indicate that Pga13 is a wall-localized protein that contributes to cell wall synthesis and is important for acquiring normal surface properties. The contribution of Pga13 to surface hydrophilicity may be important for cell dispersal during development of invasive infections, and possibly for morphological development. This is consistent with the observed reduced virulence of pga13Δ mutants in a mouse model of disseminated candidiasis.
authors.affiliation: GMCA Research Unit, Departamento de Microbiología y Ecología, Universidad de Valencia, E-46100 Burjassot, Valencia, Spain.
authors.forename: Samuel
authors.initials: S
authors.lastname: Gelis
authors.forename: Piet W J
authors.initials: PW
authors.lastname: de Groot
authors.forename: Luis
authors.initials: L
authors.lastname: Castillo
authors.forename: María-Dolores
authors.initials: MD
authors.lastname: Moragues
authors.forename: Rafael
authors.initials: R
authors.lastname: Sentandreu
authors.forename: María-Micaela
authors.initials: MM
authors.lastname: Gómez
authors.forename: Eulogio
authors.initials: E
authors.lastname: Valentín
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D002177:Candidiasis / Q000382:microbiology*; D002448:Cell Adhesion; D002473:Cell Wall / Q000378:metabolism*; D005260:Female; D005427:Flocculation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D025301:Hyphae / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D007668:Kidney / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis; D011523:Protoplasts / Q000502:physiology; D016415:Sequence Alignment; D017384:Sequence Deletion; D013312:Stress, Physiological; D013499:Surface Properties; D014774:Virulence / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins