title: Sir3 Polymorphisms in Candida glabrata clinical isolates.
abstract: The opportunistic fungal pathogen Candida glabrata adheres tightly to epithelial cells in culture, mainly through the adhesin Epa1. EPA1 is the founding member of a family of up to 23 putative adhesin-encoding genes present in the C. glabrata genome. The majority of the EPA genes are localized close to the telomeres, where they are repressed by subtelomeric silencing that depends on the Sir, Ku, Rif1, and Rap1 proteins. EPA6 and EPA7 also encode functional adhesins that are repressed in vitro. EPA1 expression in vitro is tightly controlled both positively and negatively, and in addition, presents high cell-to-cell heterogeneity, which depends on Sir-mediated silencing. In this work, we characterized the ability to adhere to HeLa epithelial cells and the expression of several EPA genes in a collection of 79 C. glabrata clinical isolates from several hospitals in Mexico. We found 11 isolates that showed increased adherence to mammalian cells compared with our reference strain under conditions where EPA1 is not expressed. The majority of these isolates displayed over-expression of EPA1 and EPA6 or EPA7, but did not show increased biofilm formation. Sequencing of the SIR3 gene of several hyper-adherent isolates revealed that all of them contain several polymorphisms with respect to the reference strain. Interestingly, two isolates have polymorphisms in positions flanked by clusters of amino acids required for silencing in the Saccharomyces cerevisiae Sir3 protein. Our data show that there is a large variability in adhesin expression and adherence to epithelial cells among different C. glabrata clinical isolates.
authors: División de Biología Molecular, IPICYT, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, San Luis Potosí, San Luis Potosí, Mexico.
authors: Verónica
authors: V
authors: Martínez-Jiménez
authors: Candy Y
authors: CY
authors: Ramírez-Zavaleta
authors: Emmanuel
authors: E
authors: Orta-Zavalza
authors: Gabriel Díaz
authors: GD
authors: de León
authors: Guadalupe
authors: G
authors: Gutiérrez-Escobedo
authors: Alfredo Ponce
authors: AP
authors: de León
authors: José
authors: J
authors: Sifuentes-Osornio
authors: Miriam Bobadilla
authors: MB
authors: del Valle
authors: Alejandro
authors: A
authors: De Las Peñas
authors: Irene
authors: I
authors: Castaño
mesh_terms: D041221:Candida glabrata / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D002177:Candidiasis / Q000382:microbiology*; D002448:Cell Adhesion; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004847:Epithelial Cells / Q000382:microbiology*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D006367:HeLa Cells; D006761:Hospitals; D006801:Humans; D008800:Mexico; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins
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