Characterization of a cell-wall acid phosphatase (PhoAp) in Aspergillus fumigatus The GenBank accession number for the A. fumigatus PHOA sequence reported in this paper is AF462065.

Abstract

In the filamentous fungus Aspergillus fumigatus, the vast majority of the cellwall-associated proteins are secreted proteins that are in transit in the cell wall. These proteins can be solubilized by detergents and reducing agents. Incubation of a SDS/β-mercaptoethanol-treated cell-wall extract with various recombinant enzymes that hydrolyse cell-wall polysaccharides resulted in the release of a unique protein in minute amounts only after incubation of the cell wall in the presence of 1,3-β-glucanase. Sequence analysis and biochemical studies showed that this glycoprotein, with an apparent molecular mass of 80 kDa, was an acid phosphatase (PhoAp) that was active on both phosphate monoesters and phosphate diesters. PhoAp is a glycosylphosphatidylinositolanchored protein that was recovered in the culture filtrate and cell-wall fraction of A. fumigatus after cleavage of its anchor. It is also a phosphaterepressible acid phosphatase. The absence of PhoAp from a phosphate-rich medium was not associated with a reduction in fungal growth, indicating that this cell-wall-associated protein does not play a role in the morphogenesis of A. fumigatus.

Galactomannoproteins of Aspergillus fumigatus

“…A. fumigatus growth is highly dependent on free phosphate availability to grow: a concentration of around 1 mM phosphate is found in serum, and A. fumigatus requires 10 times the amount available in human biological fluids for optimal growth (unpublished data). The results presented here and the identification of an acid phosphatase as the major cell wall protein (5) suggest that phosphate availability and scavenging may be a significant determinant of A. fumigatus growth in the host. Strategies to interfere with such pathways could lead to useful therapies.…”

Ectophosphatase activity in conidial forms of Fonsecaea pedrosoi is modulated by exogenous phosphate and influences fungal adhesion to mammalian cells

“…Acid phosphatases (EC 3.1.3.2) have been described in many yeasts (Vogel & Hinnen, 1990;VasilevaTonkova et al, 1996). These enzymes may exist as soluble or secreted forms (Jolivet et al, 1998), or remain attached to the outer surface of the inner membrane (Arnold et al, 1988) or cell wall (González et al, 1993;Bernard et al, 2002;Kneipp et al, 2003).…”

“…The presence of surface-located acid phosphatases, called ecto-or extracytoplasmic phosphatases, has been reported in many micro-organisms (Fernandes et al, 1997;Dutra et al, 1998;Meyer-Fernandes et al, 1999;Braibant & Content, 2001), including the fungi Saccharomyces cerevisiae (Mildner et al, 1975), Candida parapsilosis (Fernando et al, 1999), Sporothrix schenckii (Arnold et al, 1986) and Aspergillus fumigatus (Bernard et al, 2002). The specific functions of these enzymes are not fully known, but they probably participate in cell wall biosynthesis in yeast cells (Novick et al, 1981).…”

Diversity in phosphorus mobilisation and uptake in ectomycorrhizal fungi

“…From a molecular point of view, a gene coding for an acid phosphatase (XP 001887867, http://www.ncbi.nlm.nih.gov/) is available from the genome of L. bicolor recently completely sequenced (Martin et al 2008). The predicted protein is very close to the acid phosphatase AfPhoA (Q8X176) characterised in Aspergillus fumigatus (Bernard et al 2002) as well as to two other acid phosphatases identified in the basidiomycete Pholiota nameko (PNAP1: BAD00139 and PNAP2: BAD00140; Fig. 2).…”

“…2). Interestingly, the different polypeptides share three domains that are highly conserved among these acid phosphatases (Bernard et al 2002; Fig. 2).…”