Zur (FurB) is a key factor in the control of the oxidative stress response in Anabaena sp. PCC 7120

Abstract

Summary Iron and zinc are necessary nutrients whose homeostasis is tightly controlled by members of the ferric uptake regulator (FUR) superfamily in the cyanobacterium Anabaena sp. PCC7120. Although the link between iron metabolism and oxidative stress management is well documented, little is known about the connection between zinc homeostasis and the oxidative stress response in cyanobacteria. Zinc homeostasis in Anabaena is controlled by Zur, also named FurB. When overexpressed in Escherichia coli, Zur (FurB) improved cell survival during oxidative stress. In order to investigate the possible correlation between Zur and the oxidative stress response in Anabaena, zur deletion and zur‐overexpressing strains have been constructed, and the consequences of Zur imbalance evaluated. The lack of Zur increased sensitivity to hydrogen peroxide (H2O2), whereas an excess of Zur enhanced oxidative stress resistance. Both mutants displayed pleiotropic phenotypes, including alterations on the filament surfaces observable by scanning electron microscopy, reduced content of endogenous H2O2 and altered expression of sodA, catalases and several peroxiredoxins. Transcriptional and biochemical analyses unveiled that the appropriate level of Zur is required for proper control of the oxidative stress response and allowed us to identify major antioxidant enzymes as novel members of the Zur regulon.

Roles of Agrobacterium tumefaciens C58 ZntA and ZntB and the transcriptional regulator ZntR in controlling Cd2+/Zn2+/Co2+ resistance and the peroxide stress response

“…Increased zinc levels could protect some bacteria from H 2 O 2 killing (Gaballa & Helmann, 2002;Cerasi et al, 2014). However, in other bacteria, the upregulation of zinc uptake or reduction of zinc export could lead to increased sensitivity to H 2 O 2 killing (Brenot et al, 2007;Yang et al, 2007;Smith et al, 2009;Sein-Echaluce et al, 2015). Either increased zinc uptake (SPP12) or reduced zinc export (ZA141) increased intracellular zinc (Fig.…”

“…An association between zinc homeostasis and oxidative resistance has been reported (Gaballa & Helmann 2002;Yang et al, 2007;Smith et al, 2009;Cerasi et al, 2014;Sein-Echaluce et al, 2015). Zinc serves as a cofactor for oxidant-detoxifying enzymes.…”

“…The overexpression of Zur from cyanobacterium Anabaena sp. PCC 7120 confers H 2 O 2 resistance (Sein-Echaluce et al, 2015), while zur mutant strains from Xanthomonas oryzae pv. oryzae, Corynebacterium diphtheriae and Anabaena sp.…”

“…oryzae, Corynebacterium diphtheriae and Anabaena sp. PCC 7120 exhibit increased sensitivity to H 2 O 2 (Yang et al, 2007;Smith et al, 2009;Sein-Echaluce et al, 2015). In S. enterica serovar Typhimurium, the loss of zinc uptake genes znuABC and zupT leads to H 2 O 2 hypersensitivity (Cerasi et al, 2014).…”

Ferric Uptake Regulator (FUR) protein: properties and implications in cyanobacteria

“…In oxidative stress condition, FurA and FurB regulate the transcription at P furA and P furB in Anabaena sp. PCC 7120 (Hernandez et al 2004a;Sein-Echaluce et al 2014), suggesting a potential overlapping of FurA and FurB (Zur) promoters. In vivo and in vitro assays have demonstrated prxA and dpsA genes as the direct targets of FurB (Zur), and hence suggest that FurB plays an important role in connecting zinc homeostasis with oxidative stress protection in Anabaena sp.…”