Taxonomic group: fungi / Ascomycota
(Phylum: Ascomycota)
Organ / tissue: cell wall
NCBI PubMed ID: 21878570Publication DOI: 10.1128/mBio.00178-11Journal NLM ID: 101519231Publisher: Washington, DC: American Society for Microbiology
Correspondence: sarika.agarwal
umassmed.edu
Institutions: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA, Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
Fungal cell walls are predominantly composed of glucans, mannans, and chitin. Recognition of these glycans by the innate immune system is a critical component of host defenses against the mycoses. Complement, an important arm of innate immunity, plays a significant role in fungal pathogenesis, especially the alternative pathway (AP). Here we determine that the glycan monosaccharide composition and glycosidic linkages affect AP activation and C3 deposition. Furthermore, properdin, a positive regulator of the AP, contributes to these functions. AP activation by glycan particles that varied in composition and linkage was measured by C3a generation in serum treated with 10 mM EGTA and 10 mM Mg(2+) (Mg-EGTA-treated serum) (AP specific; properdin functional) or Mg-EGTA-treated serum that lacked functional properdin. Particles that contained either β1→3 or β1→6 glucans or both generated large and similar amounts of C3a when the AP was intact. Blocking properdin function resulted in 5- to 10-fold-less C3a production by particulate β1→3 glucans. However, particulate β1→6 glucans generated C3a via the AP only in the presence of intact properdin. Interestingly, zymosan and glucan-mannan particles (GMP), which contain both β-glucans and mannans, also required properdin to generate C3a. The β1→4 glycans chitin and chitosan minimally activated C3 even when properdin was functional. Finally, properdin binding to glucan particles (GP) and zymosan in serum required active C3. Properdin colocalized with bound C3, suggesting that in the presence of serum, properdin bound indirectly to glycans through C3 convertases. These findings provide a better understanding of how properdin facilitates AP activation by fungi through interaction with the cell wall components.
properdin
Structure type: fragment of a bigger structure
Location inside paper: Table 1, GP
Trivial name: glucan particle, PFLP
Compound class: cell wall polysaccharide, glucan
Contained glycoepitopes: IEDB_1397514,IEDB_142488,IEDB_146664,IEDB_153543,IEDB_158555,IEDB_161166,IEDB_2278476,IEDB_2278477,IEDB_558869,IEDB_857743,IEDB_983931,SB_192
Methods: enzyme immunoassay, electrophoresis, extraction, confocal microscopy, flow cytometry
Biological activity: glucan particles activates complement C3 from normal human serum in an antibody-independent manner through the alternative pathway in vitro
Comments, role: glucan particle contains -3)bDGlcp(1-, -6)bDGlcp(1- and traces of -4)[Ac(1-2)]bDGlcN(1-; alkaline and acidic extraction from Saccharomyces cerevisiae
Related record ID(s): 41555, 42290, 43304, 43699, 140456
NCBI Taxonomy refs (TaxIDs): 4932Reference(s) to other database(s): GTC:G51056AN
Show glycosyltransferases
There is only one chemically distinct structure:
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