Candida albicans ALS3 encodes a large cell-surface glycoprotein that has adhesive properties. Immunostaining of cultured C. albicans germ tubes showed that Als3p is distributed diffusely across the germ tube surface. Two-photon laser scanning microscopy of model catheter biofilms grown using a PALS3-green fluorescent protein (GFP) reporter strain showed GFP production in hyphae throughout the biofilm structure while biofilms grown using a PTPI1-GFP reporter strain showed GFP in both hyphae and yeast-form cells. Model catheter biofilms formed by an als3Δ/als3Δ strain were weakened structurally and had approximately half the biomass of a wild-type biofilm. Reintegration of a wild-type ALS3 allele restored biofilm mass and wild-type biofilm structure. Production of an Als3p–Agα1p fusion protein under control of the ALS3 promoter in the als3Δ/als3Δ strain restored some of the wild-type biofilm structural features, but not the wild-type biofilm mass. Despite its inability to restore wild-type biofilm mass, the Als3p–Agα1p fusion protein mediated adhesion of the als3Δ/als3Δ C. albicans strain to human buccal epithelial cells (BECs). The adhesive role of the Als3p N-terminal domain was further demonstrated by blocking adhesion of C. albicans to BECs with immunoglobulin reactive against the Als3p N-terminal sequences. Together, these data suggest that portions of Als3p that are important for biofilm formation may be different from those that are important in BEC adhesion, and that Als3p may have multiple functions in biofilm formation. Overexpression of ALS3 in an efg1Δ/efg1Δ strain that was deficient for filamentous growth and biofilm formation resulted in growth of elongated C. albicans cells, even under culture conditions that do not favour filamentation. In the catheter biofilm model, the ALS3 overexpression strain formed biofilm with a mass similar to that of a wild-type control. However, C. albicans cells in the biofilm had yeast-like morphology. This result uncouples the effect of cellular morphology from biofilm formation and underscores the importance of Als3p in biofilm development on silicone elastomer surfaces.
ChenM. H, ShenZ. M, BobinS, KahnP. C, LipkeP. N.
1995; Structure of Saccharomyces cerevisiae alpha-agglutinin. Evidence for a yeast cell wall protein with multiple immunoglobulin-like domains with atypical disulfides. J Biol Chem 270:26168–26177[CrossRef]
CostertonJ. W, ChengK. J, GeeseyG. G, LaddT. I, NickelJ. C, DasguptaM, MarrieT. J.
1987; Bacterial biofilms in nature and disease. Annu Rev Microbiol 41:435–464[CrossRef]
de NobelH,
LipkeP. N, KurjanJ.
1996; Identification of a ligand-binding site in an immunoglobulin fold domain of the Saccharomyces cerevisiae adhesion protein α -agglutinin. Mol Biol Cell 7:143–153[CrossRef]
FuY, IbrahimA. S, SheppardD. C, ChenY. C, FrenchS. W, CutlerJ. E, FillerS. G, EdwardsJ. E.Jr2002; Candida albicans Als1p: an adhesin that is a downstream effector of the EFG1 filamentation pathway. Mol Microbiol 44:61–72[CrossRef]
Garcia-SanchezS, AubertS, IraquiI, JanbonG, GhigoJ.-M, d'EnfertC.
2004; Candida albicans biofilms: a developmental state associated with specific and stable gene expression patterns. Eukaryot Cell 3:536–545[CrossRef]
GillumA. M, TsayE. Y, KirschD. R.
1984; Isolation of the Candida albicans genes for orotidine-5′-phosphate decarboxylase by complementation of S. cerevisiae ura3 and E. coli pyrF mutations. Mol Gen Genet 198:179–182[CrossRef]
GreenC. B, ChengG, ChandraJ, MukherjeeP, GhannoumM. A, HoyerL. L.
2004; RT-PCR detection of Candida albicans ALS gene expression in the reconstituted human epithelium (RHE) model of oral candidiasis and in model biofilms. Microbiology 150:267–275[CrossRef]
GreenC. B, ZhaoX, HoyerL. L.
2005a; Use of green fluorescent protein and reverse transcription-PCR to monitor Candida albicans agglutinin-like sequence gene expression in a murine model of disseminated candidiasis. Infect Immun 73:1852–1855[CrossRef]
GreenC. B, ZhaoX, YeaterK. M, HoyerL. L.
2005b; Construction and real-time RT-PCR validation of Candida albicans P ALS -GFP reporter strains and their use in flow cytometry analysis of ALS gene expression in budding and filamenting cells. Microbiology 151:1051–1060[CrossRef]
HauserK, TannerW.
1989; Purification of the inducible α -agglutinin of S. cerevisiae and molecular cloning of the gene. FEBS Lett 255:290–294[CrossRef]
HoyerL. L, PayneT. L, BellM, MyersA. M, SchererS.
1998a; Candida albicans ALS3 and insights into the nature of the ALS gene family. Curr Genet 33:451–459[CrossRef]
HoyerL. L, PayneT. L, HechtJ. E.
1998b; Identification of Candida albicans ALS2 and ALS4 and localization of Als proteins to the fungal cell surface. J Bacteriol 180:5334–5343
KapteynJ. C, HoyerL. L, HechtJ. E, MullerW. H, AndelA, VerkleijA. J, MakarowM, Van Den EndeH, KlisF. M.
2000; The cell wall architecture of Candida albicans wild-type cells and cell wall-defective mutants. Mol Microbiol 35:601–611
KruegerK. E, GhoshA. K, KromB. P, CihlarR. L.
2004; Deletion of the NOT4 gene impairs hyphal development and pathogenicity in Candida albicans . Microbiology 150:229–240[CrossRef]
KuhnD. M, ChandraJ, MukherjeeP. K, GhannoumM. A.
2002; Comparison of biofilms formed by Candida albicans and Candida parapsilosis on bioprosthetic surfaces. Infect Immun 70:878–888[CrossRef]
KumamotoC. A.
2005; A contact-activated kinase signals Candida albicans invasive growth and biofilm development. Proc Natl Acad Sci U S A 102:5576–5581[CrossRef]
KumamotoC. A, VincesM. D.
2005; Contributions of hyphae and hypha-co-regulated genes to Candida albicans virulence. Cell Microbiol 7:1546–1554[CrossRef]
LengP, LeeP. R, WuH, BrownA. J.
2001; Efg1, a morphogenetic regulator in Candida albicans , is a sequence-specific DNA binding protein. J Bacteriol 183:4090–4093[CrossRef]
LipkeP. N, WojciechowiczD, KurjanJ.
1989; AGα1 is the structural gene for the Saccharomyces cerevisiaeα -agglutinin, a cell surface glycoprotein involved in cell-cell interaction during mating. Mol Cell Biol 9:3155–3165
LiuH.
2002; Co-regulation of pathogenesis with dimorphism and phenotypic switching in Candida albicans , a commensal and a pathogen. Int J Med Microbiol 292:299–311[CrossRef]
MuradA. M, LeeP. R, BroadbentI. D, BarelleC. J, BrownA. J.
2000; CIp10, an efficient and convenient integrating vector for Candida albicans . Yeast 16:325–327[CrossRef]
MurilloL. M, NewportG, LanC.-Y, HabelitzS, DunganJ, AgabianN. M.
2005; Genome-wide transcription profiling of the early phase of biofilm formation by Candida albicans . Eukaryot Cell 4:1562–1573[CrossRef]
NobileC. J, MitchellA. P.
2005; Regulation of cell-surface genes and biofilm formation by the C. albicans transcription factor Bcr1p. Curr Biol 15:1150–1155[CrossRef]
OhS.-H, ChengG, NuessenJ. A, JajkoR, YeaterK. M, ZhaoX, PujolC, SollD. R, HoyerL. L.
2005; Functional specificity of Candida albicans Als3p proteins and clade specificity of ALS3 alleles discriminated by the number of copies of the tandem repeat sequence in the central domain. Microbiology 151:673–681[CrossRef]
PortaA, RamonA. M, FonziW. A.
1999; PRR1 , a homolog of Aspergillus nidulans palF , control pH-dependent gene expression and filamentation in Candida albicans . J Bacteriol 181:7516–7523
RamageG, SavilleS. P, WickesB. L, Lopez-RibotJ. L.
2002a; Inhibition of Candida albicans biofilm formation by farnesol, a quorum-sensing molecule. Appl Environ Microbiol 68:5459–5463[CrossRef]
RamageG, VandeWalleK, Lopez-RibotJ. L, WickesB. L.
2002b; The filamentation pathway controlled by the Efg1 regulator protein is required for normal biofilm formation and development in Candida albicans . FEMS Microbiol Lett 214:95–100[CrossRef]
SchwankS, RajacicZ, ZimmerliW, BlaserJ.
1998; Impact of bacterial biofilm formation on in vitro and in vivo activities of antibiotics. Antimicrob Agents Chemother 42:895–898
SheppardD. C, YeamanM. R, WelchW. H. 7 other authors2004; Functional and structural diversity in the Als protein family of Candida albicans . J Biol Chem 279:30480–30489[CrossRef]
StewartP. S, MukherjeeP. K, GhannoumM. A.
2004; Biofilm antimicrobial resistance. In Microbial Biofilms pp 250–268 Edited by
GhannoumM. A., O'TooleG. A.
Washington, DC: American Society for Microbiology;
ZhaoH, ShenZ. M, KahnP. C, LipkeP. N.
2001; Interaction of α -agglutinin and a-agglutinin, Saccharomyces cerevisiae sexual cell adhesion molecules. J Bacteriol 183:2874–2880[CrossRef]
ZhaoX, OhS.-H, ChengG, GreenC. B, NuessenJ. A, YeaterK, LengR. P, BrownA. J. P, HoyerL. L.
2004; ALS3 and ALS8 represent a single locus that encodes a Candida albicans adhesin; functional comparison between Als3p and Als1p. Microbiology 150:2415–2428[CrossRef]
ZhaoX, OhS.-H, YeaterK. M, HoyerL. L.
2005; Analysis of the Candida albicans Als2p and Als4p adhesins suggests the potential for compensatory function within the Als family. Microbiology 151:1619–1630[CrossRef]