Br. Braun et al., NRG1, a repressor of filamentous growth in C.albicans, is down-regulated during filament induction, EMBO J, 20(17), 2001, pp. 4753-4761
In response to a variety of external signals, the fungal pathogen Candida a
lbicans undergoes a transition between ellipsoidal single cells (blastospor
es) and filaments composed of elongated cells attached end-to-end. Here we
identify a DNA-binding protein, Nrg1, that represses filamentous growth in
Candida probably by acting through the co-repressor Tup1. nrg1 mutant cells
are predominantly filamentous under non-filament-inducing conditions and t
heir colony morphology resembles that of tup1 mutants. We also identify two
filament-specific genes, ECE1 and HWP1, whose transcription is repressed b
y Nrg1 under noninducing conditions. These genes constitute a subset of tho
se under Tup1 control, providing further evidence that Nrg1 acts by recruit
ing Tup1 to target genes. We show that growth in serum at 37 degreesC, a po
tent inducer of filamentous growth, causes a reduction of NRG1 mRNA, sugges
ting that filamentous growth is induced by the down-regulation of NRG1. Con
sistent with this idea, expression of NRG1 from a non-regulated promoter pa
rtially blocks the induction of filamentous growth.