The SskA and SrrA response regulators are implicated in oxidative stress responses of hyphae and asexual spores in the phosphorelay signaling network of Aspergillus nidulans

Daisuke Hagiwara, Yoshihiro Asano, Junichiro Marui, Kentaro Furukawa, Kyoko Kanamaru, Masashi Kato, Keietsu Abe, Tetsuo Kobayashi, Takafumi Yamashino, Takeshi Mizuno

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

Histidine-to-Aspartate (His-Asp) phosphorelay (or two-component) systems are common signal transduction mechanisms implicated in a wide variety of cellular responses to environmental stimuli in both prokaryotes and eukaryotes. For a model filamentous fungi, Aspergillus nidulans, in this study we first compiled a complete list of His-Asp phosphorelay components, including 15 genes for His-kinase (HK), four genes for response regulator (RR), and only one for histidine-containing phosphotransfer intermediate (HPt). For these RR genes, a set of deletion mutants was constructed so as to create a null allele for each. When examined these mutant strains under various conditions stressful for hyphal growth and asexual spore development, two of them (designated ΔsskA and ΔsrrA) showed a marked phenotype of hypersensitivity to oxidative stresses (particularly, to hydrogen peroxide). In this respect, expression of the vegetative-stage specific catB catalase gene was severely impaired in both mutants. Furthermore, conidia from ΔsskA were hypersensitive not only to treatment with H2O2, but also to treatment at aberrantly low (4 °C) and high (50 °C) temperatures, resulting in reduced germination efficiency. In this respect, not only the catA catalase gene specific for asexual development, but also a set of genes encoding the enzymes for synthesis of certain stress tolerant compatible solutes, such as trehalose and glycerol, were markedly downregulated in conidia from ΔsskA. These results together are indicative of the physiological importance of the His-Asp phosphorelay signaling network involving the SskA and SrrA response regulators.

Original languageEnglish
Pages (from-to)1003-1014
Number of pages12
JournalBioscience, Biotechnology and Biochemistry
Volume71
Issue number4
DOIs
Publication statusPublished - 2007 May 1

Keywords

  • Aspergillus nidulans
  • Conidia
  • Histidine-to-Aspartate (His-Asp) phosphorelay
  • Oxidative stress response
  • Response regulator

ASJC Scopus subject areas

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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