Transcription of the Hsp30, Hsp70, and Hsp90 heat shock protein genes is modulated by the PalA protein in response to acid pH-sensing in the fungus Aspergillus nidulans - PubMed (original) (raw)

Transcription of the Hsp30, Hsp70, and Hsp90 heat shock protein genes is modulated by the PalA protein in response to acid pH-sensing in the fungus Aspergillus nidulans

Janaína S Freitas et al. Cell Stress Chaperones. 2011 Sep.

Abstract

Heat shock proteins are molecular chaperones linked to a myriad of physiological functions in both prokaryotes and eukaryotes. In this study, we show that the Aspergillus nidulans hsp30 (ANID_03555.1), hsp70 (ANID_05129.1), and hsp90 (ANID_08269.1) genes are preferentially expressed in an acidic milieu, whose expression is dependent on the palA (+) background under optimal temperature for fungal growth. Heat shock induction of these three hsp genes showed different patterns in response to extracellular pH changes in the palA(+) background. However, their accumulation upon heating for 2 h was almost unaffected by ambient pH changes in the palA (-) background. The PalA protein is a member of a conserved signaling cascade that is involved in the pH-mediated regulation of gene expression. Moreover, we identified several genes whose expression at pH 5.0 is also dependent on the palA (+) background. These results reveal novel aspects of the heat- and pH-sensing networks of A. nidulans.

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Figures

Fig. 1

Fig. 1

Northern blot analysis of hsp transcripts using total RNA from the control and palA1 strains of A. nidulans. The conidia from the control (lane 1) and palA1 (lane 2) strains were grown for 7 h at 37°C in low-Pi medium buffered at pH 5.0 or pH 8.0. The mycelia were incubated at 50°C for the time indicated. The ethidium bromide-stained rRNA band is shown as the loading control. The bars indicate the relative fold expression determined from the densitometric analyses. The data represent the average values ± standard deviation (SD) from three independent blot exposures

Fig. 2

Fig. 2

Northern blot analysis of bxiA and sensor histidine kinase (_hisK_-like sensor) transcripts using total RNA from the control and palA1 strains of A. nidulans. The conidia from the control (lane 1) and palA1 (lane 2) strains were grown for 7 h at 37°C in low- or high-Pi liquid medium buffered at pH 5.0 or pH 8.0. The ethidium bromide-stained rRNA band is shown as the loading control. The bars indicate the relative fold expression determined from the densitometric analyses. The data represent the average values ± standard deviation (SD) from three independent blot exposures

Fig. 3

Fig. 3

Northern blot analysis of the gelA, atp9, and mfs transcripts using total RNA from the control, palA1, and palC4 strains of A. nidulans. The conidia from the control (lane 1), palA1 (lane 2), and palC4 (lane 3) strains were grown for 7 h at 37°C in a low-Pi liquid medium buffered at pH 5.0 or pH 8.0. The ethidium bromide-stained rRNA band is shown as the loading control. The bars indicate the relative fold expression determined from the densitometric analyses. The data represent the average values ± standard deviation (SD) from three independent blot exposures

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