A basic‐region helix–loop–helix protein‐encoding gene (devR) involved in the development of Aspergillus nidulans

Abstract

SummaryBasic-region helix-loop-helix (bHLH) proteins form an interesting class of eukaryotic transcription factors often involved in developmental processes. Here, a so far unknown bHLH protein-encoding gene of the filamentous ascomycete Aspergillus nidulans was isolated and designated devR for regulator of development. Deletion of devR revealed that the gene is non-essential for vegetative growth. However, the deletion mutant produced wrinkled colonies, a yellow pigment and did not form conidia on minimal agar plates. Conidiophore development was initiated normally, and colonies produced conidiophores with metulae and phialides. However, the phialides continued to grow filamentously and produced a second conidiophore with a vesicle at its end. The addition of KCl (0.6 M) to the medium suppressed the knock-out phenotype. The D D D D devR phenotype resembled that of a mutation in the tcsA gene encoding a histidine kinase domain and a response regulator domain. Here, we generated a tcsA deletion mutant. In a D D D D tcsA strain, a DevR-Egfp protein fusion was detected in the cytoplasm, whereas in the wild type, the protein fusion was exclusively located in the nuclei, indicating that TcsA is required for nuclear localization of DevR. devR mRNA steady-state levels were similar in sporulating and vegetatively growing mycelia, and independent of a functional brlA gene. Moreover, under all conditions tested, self-crossing of the D D D D devR mutant strain was never observed. Taken together, devR encodes a bHLH regulatory protein that is part of the tcsA signal transduction network and required for development under standard growth conditions.

In VitroAnalysis of His-Asp Phosphorelays inAspergillus nidulans: The First Direct Biochemical Evidence for the Existence of His-Asp Phosphotransfer Systems in Filamentous Fungi

“…More recently, Brakhage and his colleagues reported very interesting findings: TcsA is required for nuclear localization of the bHLH protein, DevR, which regulates conidiophore development under standard growth conditions, suggesting that the two proteins belong to the same signal transduction pathway. 32) Therefore, although there is no direct evidence at present, it is probable that the regulation of the localization of DevR is mediated by the TcsA-YpdA-SskA and/or TcsA-YpdA-SrrA phosphorelays.…”

The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species

“…Interestingly, a regulatable alcAp-anbH1 transformant was found in A. nidulans (1058), and upon growth under inducing conditions the strain showed slower growth than the WT, pointing to regulation of genes other than those in the penicillin biosynthesis pathway. Another interesting bHLH TF-encoding gene from A. nidulans is devR, which regulates sexual and asexual development (1059). A ⌬devR mutant develops conidiophores with metulae and phialide but does not form conidial chains; instead, conidiophores elongate and form additional conidiophores with a vesicle at the tip (1059).…”

Roles of the His-Asp Phosphorelay Signal Transduction System in Controlling Cell Growth and Development inAspergillus nidulans

“…These results indicate that DevR is part of the TcsA signal transduction network and that it is required for development under standard growth conditions. 21) 2. TcsB tcsB, an HK gene related to yeast osmosensor sln1 in A. nidulans, was isolated from an A. nidulans cDNA library and introduced into a temperature-sensitive osmosensing-defective sln1-ts yeast mutant.…”

“…14,15,[19][20][21][22][23][24][25][26][27][28][29] On the other hand, whole-genome sequencing offers an opportunity to identify all the HK, HPt, and RR genes in a given organism. The recently sequenced model filamentous fungus A. nidulans possesses 15 putative HK genes, four putative RR genes, and one HPt gene 19,30) (Fig.…”