Candida albicans Pmr1p, a secretory pathway P-type Ca2+/Mn2+-ATPase, is required for glycosylation and virulence.
The cell surface of Candida albicans is the immediate point of contact with the host. The outer layer of the cell wall is enriched in highly glycosylated mannoproteins that are implicated in many aspects of the host-fungus interaction. Glycosylation of cell wall proteins is initiated in the endoplasmic reticulum and then elaborated in the Golgi as the protein passes through the secretory pathway. Golgi-bound mannosyltransferases require Mn(2+) as an essential cofactor. In Saccharomyces cerevisiae, the P-type ATPase Pmr1p transports Ca(2+) and Mn(2+) ions into the Golgi. To determine the effect of a gross defect in glycosylation on host-fungus interactions of C. albicans, we disrupted the PMR1 homolog, CaPMR1. This mutation would simultaneously inhibit many Golgi-located, Mn(2+)-dependent mannosyltransferases. The Capmr1Delta null mutant was viable in vitro and had no growth defect even on media containing low Ca(2+)/Mn(2+) ion concentrations. However, cells grown in these media progressively lost viability upon entering stationary phase. Phosphomannan was almost completely absent, and O-mannan was severely truncated in the null mutant. A defect in N-linked outer chain glycosylation was also apparent, demonstrated by the underglycosylation of surface acid phosphatase. Consistent with the glycosylation defect, the null mutant had a weakened cell wall, exemplified by hypersensitivity to Calcofluor white, Congo red, and hygromycin B and constitutive activation of the cell integrity pathway. In a murine model of systemic infection, the null mutant was severely attenuated in virulence. These results demonstrate the importance of glycosylation for cell wall structure and virulence of C. albicans.
Bates
Steven
S
School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Scotland, UK.
MacCallum
Donna M
DM
Bertram
Gwyneth
G
Munro
Carol A
CA
Hughes
H Bleddyn
HB
Buurman
Ed T
ET
Brown
Alistair J P
AJ
Odds
Frank C
FC
Gow
Neil A R
NA
D000135:Acid Phosphatase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001557:Benzenesulfonates / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism / Q000502:physiology*; D002176:Candida albicans / Q000378:metabolism* / Q000472:pathogenicity*; D002473:Cell Wall / Q000378:metabolism; D002610:Cheek; D002852:Chromatography, Ion Exchange; D002855:Chromatography, Thin Layer; D003224:Congo Red / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006921:Hygromycin B / Q000737:chemistry / Q000494:pharmacology; D008345:Manganese / Q000737:chemistry; D008351:Mannans / Q000737:chemistry; D051379:Mice; D008954:Models, Biological; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009154:Mutation; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014774:Virulence
D001557:Benzenesulfonates; D008351:Mannans; D018832:Molecular Chaperones; C101767:SSC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003224:Congo Red; D006921:Hygromycin B; D008345:Manganese; D004533:Egtazic Acid; C007061:C.I. Fluorescent Brightening Agent 28; C005437:phosphomannan; D000135:Acid Phosphatase; D000252:Calcium-Transporting ATPases; D002118:Calcium