Oxidative Stress-Related Transcription Factors in the Regulation of Secondary Metabolism

Sung-Yong Hong,Ludmila Roze,John Linz

doi:10.3390/toxins5040683

Sung-Yong Hong, Ludmila Roze + Show 1 more

Open Access

https://doi.org/10.3390/toxins5040683

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Journal: Toxins	Publication Date: Apr 18, 2013
Citations: 227	License type: CC BY 3.0

Affiliation: Michigan State University

Abstract

There is extensive and unequivocal evidence that secondary metabolism in filamentous fungi and plants is associated with oxidative stress. In support of this idea, transcription factors related to oxidative stress response in yeast, plants, and fungi have been shown to participate in controlling secondary metabolism. Aflatoxin biosynthesis, one model of secondary metabolism, has been demonstrated to be triggered and intensified by reactive oxygen species buildup. An oxidative stress-related bZIP transcription factor AtfB is a key player in coordinate expression of antioxidant genes and genes involved in aflatoxin biosynthesis. Recent findings from our laboratory provide strong support for a regulatory network comprised of at least four transcription factors that bind in a highly coordinated and timely manner to promoters of the target genes and regulate their expression. In this review, we will focus on transcription factors involved in co-regulation of aflatoxin biosynthesis with oxidative stress response in aspergilli, and we will discuss the relationship of known oxidative stress-associated transcription factors and secondary metabolism in other organisms. We will also talk about transcription factors that are involved in oxidative stress response, but have not yet been demonstrated to be affiliated with secondary metabolism. The data support the notion that secondary metabolism provides a secondary line of defense in cellular response to oxidative stress.

Highlights

Living organisms including fungi and plants use a variety of signal transduction mechanisms to sense and respond to different forms of environmental stress
We focus on oxidative stress-related transcription factors, which have been shown to contribute in co-regulation of secondary metabolism, in particular aflatoxin biosynthesis, with oxidative stress response in the aspergilli
(1) Signaling pathways utilized to sense oxidative stress and to regulate target gene expression are evolutionary well conserved between filamentous fungi and yeast

Summary

Introduction

Living organisms including fungi and plants use a variety of signal transduction mechanisms to sense and respond to different forms of environmental stress. One factor in particular contributes to the complexity of filamentous fungal response to oxidative stress. Recent studies provide solid support for the notion that regulation of secondary metabolism is closely linked to the cellular response to oxidative stress in filamentous fungi [1,2,3,4,5]. We focus on oxidative stress-related transcription factors, which have been shown to contribute in co-regulation of secondary metabolism, in particular aflatoxin biosynthesis, with oxidative stress response in the aspergilli. Several of these transcription factors are directly coupled to the SAPK/MAPK pathway. Based on functional analyses of transcription factors, such as the CCAAT binding complex and Myb transcription factors, we make several predictions for the involvement of specific transcription factors, not yet reported, in co-regulation of aflatoxin biosynthesis with oxidative stress

Stress Activated Signaling Pathways in Yeast and Filamentous Fungi

CCAAT-Binding Transcription Factor Complex

Conclusions and Future