The Zinc Finger Protein Zat12 Is Required for Cytosolic Ascorbate Peroxidase 1 Expression during Oxidative Stress in Arabidopsis

Abstract

Plants are sessile organisms that evolved a complex and specialized network of regulatory genes to control their response to changes in environmental conditions. It is likely that many of these regulatory genes were initially created by gene duplication and that they later acquired roles specifically related to individual pathways or stresses as well as their combination (1, 2). Different members of gene families, such as The different regulatory networks of plants are also involved in modulating the production and scavenging of reactive oxygen species (ROS) 1 in cells. These toxic intermediates of oxygen reduction not only control different plant responses to environmental and developmental cues but also potently inhibit essential metabolic pathways and may lead to cell death (6 -9). Although a number of different enzymes and proteins produce or scavenge ROS in cells, little is known about how the different regulatory networks of plants control these enzymes and proteins and modulate the steady-state level of ROS (8 -10). The steady-state level of a number of different transcripts encoding transcription factors such as MYB, WRKY, heat shock transcription factors, and different zinc finger proteins is elevated in plants in response to different forms of ROS-induced stress (11-14). However, genetic evidence supporting a direct regulatory role for these transcripts was only presented for two zinc finger proteins, Lsd1 and Lol1, which were recently found to mediate ROS signals and control programmed cell death in Arabidopsis (6), and for heat shock transcription factor 3, which was shown to enhance cytosolic ascorbate peroxidase (Apx) expression in the absence of stress (15) We are studying the response of plants to overaccumulation of ROS in cells (i.e. oxidative stress; Ref. 9). Our goal is to identify and characterize the transcription factor network that controls the response of plants to oxidative stress. To dissect and study the ROS signal transduction network of plants, we are using knock-out plants deficient in key ROS-scavenging enzymes (13,14). These plants provide an ideal experimental system to study plant responses to ROS accumulation, because they accumulate ROS and activate multiple defense mechanisms in the absence of externally applied stimuli such as stress, ROS, or ROS generators. Moreover, the ROS that accumulate in these mutants are ROS naturally produced in cells at the different cellular ROS-producing sites and not externally applied ROS that may activate additional signaling pathways, including pathogen or abiotic stress response pathways (13,14). Knock-out plants deficient in cytosolic Apx1 are of particular interest. They maintain a high steady-state level of H 2 O 2 in cells and activate ROS defense mechanisms when grown under controlled conditions (13). These plants are also altered

The Zinc-Finger Protein Zat12 Plays a Central Role in Reactive Oxygen and Abiotic Stress Signaling in Arabidopsis

“…Recent analysis of Zat12 using transgenic plants suggested a role for Zat12 in cold acclimation and in the response of plants to oxidative stress (Rizhsky et al, 2004a;Vogel et al, 2005). However, the three different studies that used transgenic plants overexpressing Zat12 to study Zat12 function were very different in their description of plant phenotype (Iida et al, 2000;Rizhsky et al, 2004a;Vogel et al, 2005). In addition, very little overlap in transcript expression was found between the transcriptome of mature transgenic plants expressing Zat12 in experiments performed by Vogel et al (2005) and Rizhsky et al (2004a).…”

“…Recent analysis of Zat12 using transgenic plants suggested a role for Zat12 in cold acclimation and in the response of plants to oxidative stress (Rizhsky et al, 2004a;Vogel et al, 2005). However, the three different studies that used transgenic plants overexpressing Zat12 to study Zat12 function were very different in their description of plant phenotype (Iida et al, 2000;Rizhsky et al, 2004a;Vogel et al, 2005).…”

Deciphering the Role of various cis-acting regulatory elements in controlling SamDC gene expression in Rice

“…There are considerable reports on several WRKY transcription factors being induced by cold, salinity or wounding. 9,10,11 Besides the WRKY another superfamily of transcription factors in plants are the MYBs. In plants the MYB transcription factors contains R2 and R3 domains and the binding sequence varies from four to 14 nucleotides.…”

Regulation of ZAT12 protein stability: The role of hydrogen peroxide

“…It encodes a C2H2 Zn-finger transcription factor required for the upregulation of the ROS signaling-related genes APX1, ZAT7, and WRKY25. 4,5 ZAT12 protein was shown to be involved in the response to cold, oxidative and osmotic stress, salinity, and high light. 4,6,7 Recently, we showed that ZAT12 links ROS signaling and iron (Fe) acquisition, by directly interacting with the bHLH transcription factor FIT.…”

“…4,5 ZAT12 protein was shown to be involved in the response to cold, oxidative and osmotic stress, salinity, and high light. 4,6,7 Recently, we showed that ZAT12 links ROS signaling and iron (Fe) acquisition, by directly interacting with the bHLH transcription factor FIT. 8 FIT acts as a central transcriptional regulator of the Fe deficiency-induced strategy for Fe acquisition from the soil.…”