Response to Oxidative Stress Involves a Novel Peroxiredoxin Gene in the Unicellular Cyanobacterium Synechocystis sp. PCC 6803

Abstract

Exposure to methyl viologen in the presence of light facilitates the production of superoxide that gives severe damage on photosynthetic apparatus as well as many cellular processes in cyanobacteria and plants. The effects of methyl viologen on global gene expression of a unicellular cyanobacterium Synechocystis sp. strain PCC 6803 were determined by DNA microarray. The ORFs sll1621, slr1738, slr0074, slr0075, and slr0589 were significantly induced by treatment of methyl viologen for 15 min commonly under conditions of normal and high light. One of these genes, slr1738, which encodes a ferric uptake repressor (Fur)-type transcriptional regulator, is located divergently next to another induced gene, sll1621, in the genome. We deleted slr1738, and compared the global gene expression patterns of this mutant to that of wild type under non-stressed conditions. It was found that sll1621 was derepressed to the greatest extent, while many other genes including slr0589 but not slr0074 or slr0075 were derepressed to lesser extent in the mutant. Genetic disruption of sll1621, which encodes a putative type 2 peroxiredoxin, indicates that it is essential for aerobic phototrophic growth in both liquid and solid media in high light and on solid medium even in low light. Slr1738 was prepared as a His-tagged recombinant protein and shown to specifically bind to the intergenic region between sll1621 and slr1738. The binding was enhanced by dithiothreitol and abolished by hydrogen peroxide. We concluded that the Fur homolog, Slr1738, plays a regulatory role in the induction of a potent antioxidant gene, sll1621, in response to oxidative stress.

Functional characterisation of the peroxiredoxin gene family members of Synechococcus elongatus PCC 7942

“…Synechocystis PCC 6803 is the cyanobacterium studied best with respect to its antioxidant system. It expresses a superoxide dismutase (slr1516), a catalase peroxidase (sll1987) and Wve peroxiredoxins (Prx) (Kaneko et al 1996;Kobayashi et al 2004;Hosoya-Matsuda et al 2005;Dietz et al 2005;Stork et al 2005). Perelman et al (2003) analysed a double mutant of S. elongatus PCC 7942 deWcient in both the catalase and the 2-Cys Prx homologue.…”

A Comprehensive Analysis of the Peroxiredoxin Reduction System in the Cyanobacterium Synechocystis sp. Strain PCC 6803 Reveals that All Five Peroxiredoxins Are Thioredoxin Dependent

“…The Synechocystis KatG 2-Cys Prx double mutant was impaired in translation of the photosystem II D1 protein during the repair process following high-light-induced damage (42). A Synechocystis PrxII disruptant strain showed a severely reduced growth rate relative to that of the wild type strain under normal light (23,27), whereas a Synechocystis 1-Cys Prx disruption mutant grew somewhat more slowly than the wild-type strain but was not particularly sensitive to H 2 O 2 or methyl viologen (23). In contrast, an Anabaena sp.…”

The Cyanobacterial NAD Kinase Gene sll1415 Is Required for Photoheterotrophic Growth and Cellular Redox Homeostasis in Synechocystis sp. Strain PCC 6803

“…The transcript abundances of these two genes and sll1621, which was used as the positive control, were evaluated by qRT-PCR. sll1621, as a type II peroxiredoxin gene, is inducible by MV and is involved in the cellular defense against oxidative stress (18,31). As shown in Fig.…”