The Velvet Family of Fungal Regulators Contains a DNA-Binding Domain Structurally Similar to NF-κB

Ahmed, Yasar Luqman; Gerke, Jennifer; Park, Hee-Soo; Bayram, Özgür; Neumann, Piotr; Ni, Min; Dickmanns, Achim; Kim, Sun-Chang; Yu, Jae‐Hyuk; Braus, Gerhard H.; Ficner, Ralf

doi:10.1371/journal.pbio.1001750

Cited by 129 publications

(209 citation statements)

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“…We previously showed that VosA is a feedback negative regulator of brlA, and its velvet domain directly binds to the brlAb promoter (Ahmed et al 2013). The deletion of either vosA or nsdD caused elevated expression of brlA and formation of conidiophores in liquid submerged culture, where WT strains do not develop (Ni and Yu 2007) (Figure 6B).…”

Section: Additive Role Of Nsdd and Vosa In Repressing Conidiationmentioning

confidence: 83%

“…Our recent studies demonstrated that VosA and VelB control expression of various genes in conidia via directly binding to the promoters of their target genes (Ahmed et al 2013). The removal of vosA causes abnormal accumulation of brlA in conidia and vegetative cells (Ni and Yu 2007;Ahmed et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…The removal of vosA causes abnormal accumulation of brlA in conidia and vegetative cells (Ni and Yu 2007;Ahmed et al 2013). The nsdD gene was one of the target genes that are directly controlled by the VosA-VelB heterodimer in conidia, and the lower transcript of nsdD was not detectable in the DvosA or DvelB mutant conidia (Ahmed et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…This, in turn, represses brlA and, together with WetA, promotes maturation of conidia and trehalose biogenesis in spores ( Figure 1A) (Ni and Yu 2007). VosA localizes in the nucleus of mature conidia and contains the velvet DNA-binding domain recognizing 11 nucleotide sequences and a transcriptional activation domain, indicating it is a TF (Ni and Yu 2007;Ahmed et al 2013).In the present study, we specifically aimed to identify key negative regulators of conidiation that acted downstream of FluG-SfgA and likely upstream of brlA. Employing two types of sfgA deletion strains (veA+ or veA1) as recipients, we screened a pRG3-AMA1-based wild-type (WT) genomic DNA library (Osherov et al 2000) for the genes inhibiting conidiation when present in multiple copies.…”

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NsdD Is a Key Repressor of Asexual Development inAspergillus nidulans

et al. 2014

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Asexual development (conidiation) of the filamentous fungus Aspergillus nidulans occurs via balanced activities of multiple positive and negative regulators. For instance, FluG (+) and SfgA (2) govern upstream regulation of the developmental switch, and BrlA (+) and VosA (2) control the progression and completion of conidiation. To identify negative regulators of conidiation downstream of FluG-SfgA, we carried out multicopy genetic screens using sfgA deletion strains. After visually screening .100,000 colonies, we isolated 61 transformants exhibiting reduced conidiation. Responsible genes were identified as AN3152 (nsdD), AN7507, AN2009, AN1652, AN5833, and AN9141. Importantly, nsdD, a key activator of sexual reproduction, was present in 10 independent transformants. Furthermore, deletion, overexpression, and double-mutant analyses of individual genes have led to the conclusion that, of the six genes, only nsdD functions in the FluG-activated conidiation pathway. The deletion of nsdD bypassed the need for fluG and flbA$flbE, but not brlA or abaA, in conidiation, and partially restored production of the mycotoxin sterigmatocystin (ST) in the DfluG, DflbA, and DflbB mutants, suggesting that NsdD is positioned between FLBs and BrlA in A. nidulans. Nullifying nsdD caused formation of conidiophores in liquid submerged cultures, where wild-type strains do not develop. Moreover, the removal of both nsdD and vosA resulted in even more abundant development of conidiophores in liquid submerged cultures and high-level accumulation of brlA messenger (m)RNA even at 16 hr of vegetative growth. Collectively, NsdD is a key negative regulator of conidiation and likely exerts its repressive role via downregulating brlA.T HE filamentous ascomycete Aspergillus nidulans has served as an excellent model system for studying cell biology, asexual development (conidiation), and secondary metabolism (Timberlake 1990;Martinelli 1994;Yu and Keller 2005). The A. nidulans asexual reproductive cycle can be divided into two distinct phases: growth and development. The growth phase involves germination of an asexually derived spore called a conidium and formation of an undifferentiated network of interconnected hyphal cells that form the mycelium. After a certain vegetative growth period, under appropriate conditions, some of the hyphal cells stop normal growth and begin development by forming complex structures called conidiophores that bear multiple chains of conidia (Adams et al. 1988;Park and Yu 2012a).A key and essential step for conidiophore development in Aspergillus is the activation of brlA, which encodes a C 2 H 2 zinc-finger transcription factor (TF) ( Figure 1A) (Adams et al. 1988;Chang and Timberlake 1993). Further genetic and biochemical studies identified the additional key regulators abaA and wetA that function during the middle and late stages of conidiation, respectively ( Figure 1A) (Sewall et al. 1990;Andrianopoulos and Timberlake 1991;Marshall and Timberlake 1991). These three genes have been proposed to define a c...

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Section: Additive Role Of Nsdd and Vosa In Repressing Conidiationmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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NsdD Is a Key Repressor of Asexual Development inAspergillus nidulans

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Microarray hybridization analysis of light-dependent gene expression inPenicillium chrysogenumidentifies bZIP transcription factor PcAtfA

Wolfers

Kamerewerd

Nowrousian

et al. 2015

J. Basic Microbiol.

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The fungal velvet complex is a light-dependent master regulator of secondary metabolism and development in the major penicillin producer, Penicillium chrysogenum. However, the light-dependent mechanism is unclear. To identify velvet-dependent transcriptional regulators that show light-regulated expression, we performed microarray hybridizations with RNA isolated from P. chrysogenum ΔPcku70 cultures grown under 13 different long-term, light-dependent growth conditions. We compared these expression data to data from two velvet complex deletion mutants; one lacked a subunit of the velvet complex (ΔPcvelA), and the other lacked a velvet-associated protein (ΔPclaeA). We sought to identify genes that were up-regulated in light, but down-regulated in ΔPcvelA and ΔPclaeA. We identified 148 co-regulated genes that displayed this regulatory pattern. In silico analyses of the co-regulated genes identified six proteins with fungal-specific transcription factor domains. Among these, we selected the bZIP transcription factor, PcAtfA, for functional characterization in deletion and complementation strains. Our data clearly indicates that PcAtfA governs spore germination. This comparative analysis of different microarray hybridization data sets provided results that may be useful for identifying genes for future functional analyses.

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