Affiliation:
1. Department of Genetics, University of Melbourne, Victoria 3010, Australia
Abstract
ABSTRACT
Fungi are small eukaryotes capable of undergoing multiple complex developmental programs. The opportunistic human pathogen
Penicillium marneffei
is a dimorphic fungus, displaying vegetative (proliferative) multicellular hyphal growth at 25°C and unicellular yeast growth at 37°C.
P. marneffei
also undergoes asexual development into differentiated multicellular conidiophores bearing uninucleate spores. These morphogenetic processes require regulated changes in cell polarity establishment, cell cycle dynamics, and nuclear migration. The RFX (regulatory factor X) proteins are a family of transcriptional regulators in eukaryotes. We sought to determine how the sole
P. marneffei
RFX protein, RfxA, contributes to the regulation of morphogenesis. Attempts to generate a haploid
rfxA
deletion strain were unsuccessful, but we did isolate an
rfxA
+
/
rfxA
Δ heterozygous diploid strain. The role of RfxA was assessed using conditional overexpression, RNA interference (RNAi), and the production of dominant interfering alleles. Reduced RfxA function resulted in defective mitoses during growth at 25°C and 37°C. This was also observed for the heterozygous diploid strain during growth at 37°C. In contrast, overexpression of
rfxA
caused growth arrest during conidial germination. The data show that
rfxA
must be precisely regulated for appropriate nuclear division and to maintain genome integrity. Perturbations in
rfxA
expression also caused defects in cellular proliferation and differentiation. The data suggest a role for RfxA in linking cellular division with morphogenesis, particularly during conidiation and yeast growth, where the uninucleate state of these cell types necessitates coupling of nuclear and cellular division tighter than that observed during multinucleate hyphal growth.
Publisher
American Society for Microbiology
Subject
Molecular Biology,General Medicine,Microbiology
Cited by
25 articles.
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