Loss of Cell Wall Mannosylphosphate in Candida albicans Does Not Influence Macrophage Recognition

doi:10.1074/jbc.M405003200

Loss of Cell Wall Mannosylphosphate in Candida albicans Does Not Influence Macrophage Recognition*

^‡School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, United Kingdom, the ^¶Research Institute for Children, Children's Hospital, New Orleans, Louisiana 70118, and the ^∥Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, United Kingdom

** To whom correspondence should be addressed. Tel.: 44-1224-555879; Fax: 44-1224-555844; E-mail n.gow{at}abdn.ac.uk.

Abstract

The outer layer of the cell wall of the human pathogenic fungus Candida albicans is enriched with heavily mannosylated glycoproteins that are the immediate point of contact between the fungus and cells of the host, including phagocytes. Previous work had identified components of the acid-labile fraction of N-linked mannan, comprising β-1,2-linked mannose residues attached via a phosphodiester bond, as potential ligands for macrophage receptors and modulators of macrophage function. We therefore isolated and disrupted the CaMNN4 gene, which is required for mannosyl phosphate transfer and hence the attachment of β-1,2 mannose oligosaccharides to the acid-labile N-mannan side chains. With the mannosylphosphate eliminated, the mnn4Δ null mutant was unable to bind the charged cationic dye Alcian Blue and was devoid of acid-labile β-1,2-linked oligomannosaccharides. The mnn4Δ mutant was unaffected in cell growth and morphogenesis in vitro and in virulence in a murine model of systemic C. albicans infection. The null mutant was also not affected in its interaction with macrophages. Mannosylphosphate is therefore not required for macrophage interactions or for virulence of C. albicans.

Footnotes

↵1 The abbreviations used are: ORF, ORF, open reading frame; FACE, fluorophore-assisted carbohydrate electrophoresis; RBMDM, rat bone marrow-derived macrophages; MBMDM, mouse bone marrow-derived macrophages; DMEM10, Dulbecco's modified Eagle's medium 10; PBS, phosphate-buffered saline; mAb, monoclonal antibody.
↵2 J. Cutler, unpublished results.
↵* This work was supported by a fellowship from the Royal College of Pathologists/Association of Clinical Pathologists (to R. P. H.) and Well-come Trust Grants 063204 and 72263 and by NIAID, National Institutes of Health Grant RO1 24912 (to J. E. C.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵§ Present address: Mycology Reference Centre, Leeds General Infirmary, Leeds, LS1 3EX, UK.
- Received May 5, 2004.
- Revision received July 21, 2004.
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