ALS3 and ALS8 represent a single locus that encodes a Candida albicans adhesin; functional comparisons between Als3p and Als1p

Abstract

The ALS (agglutinin-like sequence) gene family of Candida albicans encodes eight cell-surface glycoproteins, some of which are involved in adherence to host surfaces. A mutational analysis of each ALS gene is currently being performed to deduce the functions of the encoded proteins and to better understand the role of these proteins in C. albicans biology and pathogenesis. This paper describes construction of an als3/als3 mutant and comparison of its phenotype to an als1/als1 strain. Efforts to disrupt ALS3 indicated that the gene could be deleted in two transformation steps, suggesting that the gene is encoded by a single locus and that the ALS3-like locus, ALS8, does not exist. Strains lacking ALS3 or ALS1 did not exhibit a defect in germ tube formation when grown in RPMI 1640 medium, but the als1/als1 mutant formed significantly fewer germ tubes in Lee medium. Analysis of ALS3 and ALS1 promoter activity using green fluorescent protein (GFP) reporter strains and flow cytometry showed that when cells are placed into medium that promotes germ tube formation, ALS1 is transcribed prior to ALS3. Comparison of the mutant strains in adhesion assays showed that the als3/als3 strain was defective in adhesion to both human umbilical vein endothelial cells (HUVEC) and buccal epithelial cells (BEC), but not to fibronectin-coated plastic plates. In contrast, the als1/als1 strain showed decreased adherence to HUVEC, but adherence to BEC and fibronectin were the same as wild-type controls. Inoculation of the buccal reconstituted human epithelium (RHE) model of oral candidiasis with the mutant strains showed nearly a total lack of adhesion and epithelial destruction by the als3/als3 mutant while the als1/als1 strain showed only a slightly reduced degree of epithelial destruction compared to the wild-type control. Adhesion data presented here suggest that, in the assays performed, loss of Als3p affects C. albicans adhesion more than loss of Als1p.Collectively, these results demonstrate functional similarities and differences between Als1p and Als3p, and suggest the potential for more complex interrelationships between the ALS genes and their encoded proteins.

Analysis of the Candida albicans Als2p and Als4p adhesins suggests the potential for compensatory function within the Als family

“…1). Construction of pHUL was described previously (Zhao et al, 2004). Briefly, pHUL contains restriction sites 59 and 39 of the Ura-blaster cassette into which the flanking regions from any ALS gene can be cloned.…”

“…The ability of C. albicans to adhere to host surfaces is positively correlated with its pathogenicity (Calderone & Braun, 1991). The ALS family of C. albicans includes eight genes that encode large cellsurface glycoproteins (Hoyer, 2001;Zhao et al, 2004). Adhesive function has been shown for Als1p and Als3p in C. albicans (Fu et al, 2002;Zhao et al, 2004).…”

“…The ALS family of C. albicans includes eight genes that encode large cellsurface glycoproteins (Hoyer, 2001;Zhao et al, 2004). Adhesive function has been shown for Als1p and Als3p in C. albicans (Fu et al, 2002;Zhao et al, 2004). Overproduction of other Als proteins in Saccharomyces cerevisiae produced an adherent phenotype for this normally non-adherent organism, suggesting they may also play a role in C. albicans adhesion (Gaur & Klotz, 1997;Sheppard et al, 2004).…”

Efg1-mediated Recruitment of NuA4 to Promoters Is Required for Hypha-specific Swi/Snf Binding and Activation inCandida albicans

“…Deletion of SWI1 or SNF2 blocks hyphal development and the expression of hypha-specific genes under all hyphal induction conditions examined. ECE1, HWP1, and ALS3 are the first few hypha-specific genes identified (Birse et al, 1993;Hoyer et al, 1998;Staab and Sundstrom, 1998;Zhao et al, 2004). Although the UAS regions for HWP1 and ALS3 have been mapped (Argimon et al, 2007;Kim et al, 2007), how Efg1 regulates their expression has not been elucidated.…”

Influência do cobre no padrão de expressão de genes envolvidos na interação de Paracoccidioides brasiliensis com a matriz extracelular

“…Entretanto, até agora não dispomos de cepas mutantes para estes genes. Cepas mutantes foram descritas em Candida albicans (SUNDSTROM et al, 2002;ZHAO et al, 2004), C.…”