Functional Analysis of atfA Gene to Stress Response in Pathogenic Thermal Dimorphic Fungus Penicillium marneffei

Abstract

Penicillium marneffei, the pathogenic thermal dimorphic fungus is a causative agent of a fatal systemic disease, penicilliosis marneffei, in immunocompromised patients especially HIV patients. For growth and survival, this fungus has to adapt to environmental stresses outside and inside host cells and this adaptation requires stress signaling pathways and regulation of gene expression under various kinds of stresses. In this report, P. marneffei activating transcription factor (atfA) gene encoding bZip-type transcription factor was characterized. To determine functions of this gene, atfA isogenic mutant strain was constructed using the modified split marker recombination method. The phenotypes and susceptibility to varieties of stresses including osmotic, oxidative, heat, UV, cell wall and cell membrane stresses of the mutant strain were compared with the wild type and the atfA complemented strains. Results demonstrated that the mRNA expression level of P. marneffei atfA gene increased under heat stress at 42°C. The atfA mutant was more sensitive to sodium dodecyl sulphate, amphotericin B and tert-butyl hydroperoxide than the wild type and complemented strains but not hydrogen peroxide, menadione, NaCl, sorbitol, calcofluor white, itraconazole, UV stresses and heat stress at 39°C. In addition, recovery of atfA mutant conidia after mouse and human macrophage infections was significantly decreased compared to those of wild type and complemented strains. These results indicated that the atfA gene was required by P. marneffei under specific stress conditions and might be necessary for fighting against host immune cells during the initiation of infection.

The bZIP transcription factor VdAtf1 regulates virulence by mediating nitrogen metabolism in Verticillium dahliae

“…Atf1 is a well‐studied bZIP transcription factor in filamentous fungi and its ability to respond to oxidative stresses through its role in virulence is substantially different between species. For example, Atf1 orthologs regulate both oxidative resistance and virulence in M. oryzae , F. graminearum , C. purpurea and P. marneffei (Nathues et al , 2004; Guo et al , 2010; Nimmanee et al , 2014; Jiang et al , 2015). However, in C. neoformans , the Atf1 ortholog is involved in response to oxidative stresses but has a dispensable effect on virulence (Missall & Lodge, 2005).…”

“…For instance, CPTF1 in Claviceps purpurea , FgATF1 in F. graminearum and MoAtf1 in M. oryzae oxidative stress response and defense (Nathues et al , 2004; Guo et al , 2010; Jiang et al , 2015), while in Botrytis cinerea , BcAtf1 affects several signaling and differentiation processes, as well as secondary metabolism and regulates conidia production (Temme et al , 2012). The Atf1 homolog atfA of Penicillium marneffei is involved in pathogenicity and resistance to some specific stresses such as sodium dodecyl sulphate, amphotericin B and tert‐butyl hydroperoxide (Nimmanee et al , 2014). Most of these studies have focused on the resistance to reactive oxygen species (ROS) while few reports have noted nitrogen metabolism.…”

Genome-wide transcriptome analysis ofAspergillus fumigatusexposed to osmotic stress reveals regulators of osmotic and cell wall stresses that are SakAHOG1and MpkC dependent

“…Accordingly, Δ atfC and Δ atfD seem to provide a minor contribution to virulence. To our knowledge, ATF1 orthologues have been characterized only in two other human pathogenic fungi, Cryptococcus neoformans and Penicillium marneffei (Missall & Lodge, ; Jung et al, ; Kim et al, ; Nimmanee, Woo, Vanittanakom, Youngchim, & Vanittanakom, ). The Cryptococcus neoformans Atf1 orthologue was dependent on carbonic anhydrases and played an important role in several kinds of stress responses, such as thermo‐tolerance, antifungal drug resistance, regulation of thioreodoxin expression, repression of melanin and capsule production, and virulence (Missall & Lodge, ; Kim et al, ; Jung et al, ).…”

“…In the dimorphic fungus P. marneffei , recovery of Δ atfA mutant conidia after mouse and human macrophage infections was significantly decreased. This strongly suggested that under specific stress conditions, AtfA was required by P. marneffei , potentially contributing to the fight against the host immune response during the establishment of infection (Nimmanee et al, ).…”

“…Accordingly, ΔatfC and ΔatfD seem to provide a minor contribution to virulence. To our knowledge, ATF1 orthologues have been characterized only in two other human pathogenic fungi, Cryptococcus neoformans and Penicillium marneffei (Missall & Lodge, 2005;Jung et al, 2015;Kim et al, 2010;Nimmanee, Woo, Vanittanakom, Youngchim, & Vanittanakom, 2014). The Cryptococcus neoformans This strongly suggested that under specific stress conditions, AtfA was required by P. marneffei, potentially contributing to the fight against the host immune response during the establishment of infection (Nimmanee et al, 2014).…”