%0 Journal Article %A Galán, Amparo %A Casanova, Manuel %A Murgui, Amelia %A MacCallum, Donna M. %A Odds, Frank C. %A Gow, Neil A. R. %A Martínez, José P. %T The Candida albicans pH-regulated KER1 gene encodes a lysine/glutamic-acid-rich plasma-membrane protein that is involved in cell aggregation %D 2004 %J Microbiology, %V 150 %N 8 %P 2641-2651 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.26339-0 %K CSH, cell-surface hydrophobicity %K Con A, concanavalin A %I Microbiology Society, %X Immunoscreening of a Candida albicans cDNA library with a polyclonal germ-tube-specific antibody (pAb anti-gt) resulted in the isolation of a gene encoding a lysine/glutamic-acid-rich protein, which was consequently designated KER1. The nucleotide and deduced amino acid sequences of this gene displayed no significant homology with any other known sequence. KER1 encodes a 134 kDa lysine (14·5 %)/glutamic acid (16·7 %) protein (Ker1p) that contains two potential transmembrane segments. KER1 was expressed in a pH-conditional manner, with maximal expression at alkaline pH and lower expression at pH 4·0, and was regulated by RIM101. A Δker1/Δker1 null mutant grew normally but was hyperflocculant under germ-tube-inducing conditions, yet this behaviour was also observed in stationary-phase cells grown under other incubation conditions. Western blotting analysis of different subcellular fractions, using as a probe a monospecific polyclonal antibody raised against a highly antigenic domain of Ker1p (pAb anti-Ker1p), revealed the presence of a 134 kDa band in the purified plasma-membrane fraction from the wild-type strain that was absent in the homologous preparation from Δker1/Δker1 mutant. The pattern of cell-wall protein and mannoprotein species released by digestion with β-glucanases, reactive towards pAbs anti-gt and anti-Ker1p, as well as against concanavalin A, was also different in the Δker1/Δker1 mutant. Mutant strains also displayed an increased cell-surface hydrophobicity and sensitivity to Congo red and Calcofluor white. Overall, these findings indicate that the mutant strain was affected in cell-wall composition and/or structure. The fact that the ker1 mutant had attenuated virulence in systemic mouse infections suggests that this surface protein is also important in host–fungus interactions. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.26339-0