Functional analysis of Hsp70 family protein SsaA in Aspergillus oryzae

Ref ID: 18468

Author:

Ayumi Ohba, Mizuki Tanaka, Takahiro Shintani, Katsuya Gomi

Author address:

Division of Bioscience and Biotechnology for Future Bioindustries Graduate School of Agricultural Science, Tohoku
University, Japan

Full conference title:

11 th European Conference on Fungal Genetics

Abstract:

One of the possible mechanisms of azole resistance is the up8208;regulation of genes encoding drug efflux pumps,
mainly belonging to ABC transporters. Aspergillus oryzae exhibits azole drug resistance through overexpression of
ABC transporter genes such as atrA, atrF, and atrG. Expression of these transporter genes is regulated by a
Zn(II)Cys6 transcription factor, AtrR. Although it was suggested that AtrR shows different responses dependent on
azole drug species, the detailed mechanism underlying regulation of AtrR in expression of the ABC transporter
genes has not been elucidated. Since in Saccharomyces cerevisiae the AtrR counterpart Pdr1/Pdr3 are associated
with Mediator protein complex, we examined whether or not there are Mediator8208;like proteins or co8208;activators
interacted with AtrR in A. oryzae. To identify such proteins, a tandem affinity purification (TAP) moiety was fused
to AtrR, with which candidate proteins prepared from the fungal mycelium were co8208;immunoprecipitated. The
tandem mass spectrometry analysis showed that one of proteins enriched in the co8208;immunoprecipitated fraction
was Hsp70 family protein, an ortholog of yeast Ssa1 (SsaA). In S. cerevisiae Pdr1 is positively regulated by Hsp70
protein Ssz1 and Pdr3 is negatively regulated by Ssa1/2. We constructed an overexpression strain of ssaA in A.
oryzae and examined the involvement of the gene in the drug resistance. Overexpression of ssaA resulted in a
slight decrease in azole drug resistance. In addition, this strain also showed a decrease in the expression of ABC
transporter genes (atrA, atrF, and atrG). These results suggested that AtrR is negatively regulated by SsaA in A.
oryzae.

Abstract Number: PR1.56

Conference Year: 2012

Link to conference website: http://www.ecfg.info/images/Abstract_Book_Electronic.pdf

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