Out of the iron age: new insights into the critical role of manganese homeostasis in bacteria

Oxidative stress tolerance is manganese (Mn2+) regulated in Streptococcus gordonii

“…One of the most important enzymes in oxidative stress tolerance is SOD, and there is now substantial agreement that MnSOD acts as a major protectant against toxic O − # anions in streptococci Manganese and oxidative stress in S. gordonii (Jakubovics & Jenkinson, 2001). In this article we demonstrate that S. gordonii produces a single SOD, which is Mn# + -dependent, based upon sequence comparisons with other MnSOD proteins and our enzyme inhibition profile.…”

Disruption of sitA Compromises Sinorhizobium meliloti for Manganese Uptake Required for Protection against Oxidative Stress

“…Having established the ability of MnSO 4 to alleviate the sensitivity of the sitA::mTn5 mutant to both H 2 O 2 and plumbagin, we sought to determine the mechanism(s) through which manganese was acting to provide oxidative stress protection. There is an increasing list of enzymes that require Mn 2ϩ for activity (26). S. meliloti encodes a superoxide dismutase (SodB) that can use either Fe 2ϩ or Mn 2ϩ as a cofactor but shows a much higher activity when utilizing Mn 2ϩ (40).…”

“…Iron is used as a cofactor in defense enzymes such as catalase (4). Although in this context iron is helpful in protection against ROS, free iron in the Fe 2ϩ state can serve to exacerbate oxidative stress by producing hydroxyl radicals from peroxides through Fenton chemistry (26). In contrast to iron, manganese ions can help defend against ROS by scavenging both H 2 O 2 and superoxide, as part of low-molecular-weight complexes with cellular ligands such as phosphate, lactate, or bicarbonate.…”

Corynebacterium ammoniagenes class Ib ribonucleotide reductase: transcriptional regulation of an atypical genomic organization in the nrd cluster

“…Manganese homeostasis is controlled in a similar way by the DtxR-like protein MntR (Jakubovics & Jenkinson, 2001). There is a high degree of similarity between the consensus sequences for these metal regulatory boxes and the stretch of 24 nt described in the nrd sequences, but very little is known about C. ammoniagenes ironor manganese-regulated genes.…”

“…In fact, manganese turns out to be a very important cation within the bacterial world, playing essential roles such as detoxifying a variety of reactive oxygen species and consequently, protecting bacteria from oxidative stress (Jakubovics & Jenkinson, 2001). In our study, we also showed that the effect of manganese on DNA replication should be looked for at the transcriptional regulation level instead of at the protein level of the class Ib RNR (SchimpffWeiland et al, 1981;Willing et al, 1988).…”