Abstract
Sensor histidine kinases (HKs) are important factors that control cellular growth in response to environmental conditions. The expression of 15 HKs from Aspergillus nidulans was analyzed by quantitative real-time PCR under vegetative, asexual, and sexual growth conditions. Most HKs were highly expressed during asexual growth. All HK gene-disrupted strains produced reactive oxygen species (ROS). Three HKs are involved in the control of ROS: HysA was the most abundant under the restricted oxygen condition, NikA is involved in fungicide sensing, and FphA inhibits sexual development in response to red light. Phosphotransfer signal transduction via HysA is essential for ROS production control.
Highlights
His-Asp phosphorelay signal transduction helps cells adapt to environmental changes and is common among bacterial and some eukaryotic cells
A few histidine kinase (HK) were expressed during vegetative growth (Fig. 1A), whereas solution for 4 h and observed under a microscope. (B) Left drawing: after the germination of conidia, hyphae grew in the direction of the arrow in liquid culture
ΔhysA and ΔnikA were constructed by using a host strain (ABPU1) different from those of ΔphkA and ΔphkB (ABPU1ΔligD)
Summary
His-Asp phosphorelay signal transduction helps cells adapt to environmental changes and is common among bacterial and some eukaryotic cells. Sensor histidine kinases (HKs) recognize external signals, autophosphorylate on their own histidine residues, transfer phosphoryl groups to their own aspartic acid residues, and subsequently transfer the phosphate signals to histidine-containing phosphor transmitter (HPt). Response regulators (RRs) receive the phosphate signals on their aspartic acid residues and regulate gene expressions directly or by controlling the downstream signal transduction pathways. Aspergillus nidulans is a model filamentous fungus that contains 15 HKs, 1 HPt, and 4 RRs [1]. Several HKs have been studied in attempts to characterize the roles of His-Asp phosphorelay systems in A. nidulans. ROS signals are reported to be essential for the normal growth and development of A. nidulans [9]. 15 HKs in A. nidulans were characterized by analyzing their expression profiles by quantitative real-time PCR. ROS products were observed by microscopy in HK gene-disrupted strains
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