Visual expression analysis of the responses of the alternative oxidase gene (aox1) to heat shock, oxidative, and osmotic stresses in conidia of citric acid-producing Aspergillus niger

Yuki Honda, Takasumi Hattori, Kotaro Kirimura

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    The citric acid-producing filamentous fungus Aspergillus niger WU-2223L shows cyanide-insensitive respiration catalyzed by alternative oxidase in addition to the cytochrome pathway. Sequence analysis of the 5' flanking region of the alternative oxidase gene (aox1) revealed a potential heat shock element (HSE) and a stress response element (STRE). We have previously confirmed aox1 expression in conidia. In this study, to confirm whether the upstream region of aox1 responds to various stresses, we used a visual expression analysis system for single-cell conidia of the A. niger strain AOXEGFP-1. This strain harbored a fusion gene comprising aox1 and egfp, which encodes the enhanced green fluorescent protein (EGFP). The fluorescence intensity of EGFP increased in conidia of A. niger AOXEGFP-1 that were subjected to heat shock at 35-45°C, oxidative stress by exposure to 5. mM paraquat or 1. mM. t-butylhydroperoxide, or osmotic stresses by exposure to 0.5. M KCl or 1.0. M mannitol. These results indicate that the putative HSE and STRE in the upstream region of aox1 directly or indirectly respond to heat shock, oxidative, and osmotic stresses.

    Original languageEnglish
    Pages (from-to)338-342
    Number of pages5
    JournalJournal of Bioscience and Bioengineering
    Issue number3
    Publication statusPublished - 2012 Mar



    • Alternative oxidase
    • Aspergillus niger
    • Conidium
    • Green fluorescent protein
    • Single-cell analysis

    ASJC Scopus subject areas

    • Biotechnology
    • Applied Microbiology and Biotechnology
    • Bioengineering

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