Pathogenic and non-pathogenic fungi synthesize
glycosphingolipids, which have a crucial role in growth and viability.
Glycosphingolipids also contribute to fungal-associated pathogenesis. The opportunistic yeast pathogen Candida albicans synthesizes
phospholipomannan (PLM), which is a
glycosphingolipid of the mannosylinositol phosphorylceramide family. Through its
lipid and
glycan moieties, PLM contributes to the initial recognition of the yeast, causing
immune system disorder and persistent
fungal disease through activation of host signaling pathways. The
lipid moiety of PLM activates the deregulation signaling pathway involved in yeast phagocytosis whereas its
glycan moiety, composed of β-1,2
mannosides (β-Mans), participates to inflammatory processes through a mechanism involving
Galectin-3. Biosynthesis of PLM β-Mans involves two β-1,2
mannosyltransferases (Bmts) that initiate (Bmt5) and elongate (Bmt6) the
glycan chains. After generation of double bmtsΔ mutants, we show that Bmt5 has redundant activity with Bmt2, which can replace Bmt5 in bmt5Δ mutant. We also report that PLM is located in the inner layer of the yeast cell wall. PLM seems to be not essential for systemic
infection of the yeast. However, defect of PLM β-mannosylation increases resistance of C. albicans to inhibitors of β-
glucans and
chitin synthesis, highlighting a role of PLM in cell wall homeostasis.