Occurrence of two superoxide dismutases in Aeromonas hydrophila: molecular cloning and differential expression of the sodA and sodB genes

Leclère, Valérie; Chotteau-Lelièvre, Anne; Gancel, Frédérique; Imbert, Marlène; Blondeau, R.

doi:10.1099/00221287-147-11-3105

Cited by 15 publications

(15 citation statements)

References 31 publications

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“…Mn-SODs tend to be exported via Sec as unfolded proteins and hence acquire their metal outside the cell, where competition with iron may not be an issue (Fig. 1, B and C) (22)(23)(24)(25)(26). Such a model for metal ion selectivity by cell compartmentalization has previously been described by Robinson and colleagues (28) for other periplasmic metalloproteins.…”

Section: Mishaps In Metal Insertion Into Mn-sodmentioning

confidence: 57%

“…Although bacterial Mn/Fe-SODs are generally cytosolic, there are rare exceptions in which the enzyme is secreted into the periplasmic or extracellular space (22)(23)(24)(25)(26). Bacteria can export unfolded proteins through the Sec system or will use the twin-arginine translocation (TAT) system for exporting prefolded mature polypeptides (27).…”

Section: Mishaps In Metal Insertion Into Mn-sodmentioning

confidence: 99%

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Battles with Iron: Manganese in Oxidative Stress Protection

Aguirre

Culotta

2012

Journal of Biological Chemistry

262

204

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The redox-active metal manganese plays a key role in cellular adaptation to oxidative stress. As a cofactor for manganese superoxide dismutase or through formation of non-proteinaceous manganese antioxidants, this metal can combat oxidative damage without deleterious side effects of Fenton chemistry. In either case, the antioxidant properties of manganese are vulnerable to iron. Cellular pools of iron can outcompete manganese for binding to manganese superoxide dismutase, and through Fenton chemistry, iron may counteract the benefits of non-proteinaceous manganese antioxidants. In this minireview, we highlight ways in which cells maximize the efficacy of manganese as an antioxidant in the midst of pro-oxidant iron.In biology, iron and manganese play important roles in oxygen chemistry. Both metals are used in oxygen evolution through photosynthesis and can also serve as cofactors for enzymes that remove harmful byproducts of O 2 metabolism such as superoxide (O 2 . ) and hydrogen peroxide, yet a major difference lies in the propensity of these metals to cause oxidative damage. Iron is well known for its reactivity with peroxide, generating the highly reactive hydroxyl radical through so-called Fenton chemistry. Manganese is less prone to such chemistry due to a higher reduction potential. Iron is often considered a pro-oxidant in biology under situations in which manganese is an antioxidant. Without the deleterious side effects of Fenton chemistry, manganese can safely operate as a cofactor for superoxide dismutase (SOD) 2 enzymes and also provide oxidative stress resistance through formation of nonproteinaceous manganese-based antioxidants. Herein, we focus on these two biological roles of manganese in oxidative stress protection and the potential challenges faced by competing pools of iron. Manganese Versus Iron as Cofactors for SODSOD enzymes fall into three distinct families that are unrelated in sequence but have converged in evolution to utilize a redox-active metal to disproportionate O 2 . into hydrogen peroxide and oxygen. These families are classified according to metal cofactor and include Cu,Zn-SODs, which use copper for catalysis and also bind a structural zinc atom; a rarer family of nickel-containing SODs (1); and an extensive Mn/Fe-SOD family that uses either manganese or iron. Members of the Mn/Fe-SOD family are widespread in biology and are thought to have evolved from a common ancestor prior to the divergence of eubacteria, archaebacteria, and eukaryotes over 3 billion years ago (2, 3). The active sites of Mnand Fe-SODs are virtually indistinguishable. The manganese or iron cofactor is coordinated to three histidines, one aspartate, and one solvent molecule in a distorted trigonal bipyramidal geometry. Outside the active site, the overall primary sequence and tertiary folds of Mn-and Fe-SODs are remarkably similar. Despite this striking conservation, these SODs are exquisitely metal-specific; for example, a Mn-SOD is active only with manganese and not iron. Rare exceptions include so-called ...

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Section: Mishaps In Metal Insertion Into Mn-sodmentioning

confidence: 57%

Section: Mishaps In Metal Insertion Into Mn-sodmentioning

confidence: 99%

Battles with Iron: Manganese in Oxidative Stress Protection

Aguirre

Culotta

2012

Journal of Biological Chemistry

262

204

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“…Because D. vulgaris is not a pathogen, it is not exposed to large amounts of superoxide produced externally by other cells (e.g., macrophages). Sod is therefore more likely to function in the removal of periplas- (12,32,37) or the Mn type (16,19). Although periplasmic CuZn-Sods have typical Sec system-dependent signal sequences, a twin-arginine leader sequence has been found in periplasmic Mn-Sod (19).…”

Section: Reduction Of Oxygen Entering the Cytoplasm Of D Vulgarismentioning

confidence: 99%

Function of Oxygen Resistance Proteins in the Anaerobic, Sulfate-Reducing Bacterium Desulfovibrio vulgaris Hildenborough

Fournier

Zhang²,

Wildschut³

et al. 2003

J Bacteriol

101

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Two mutant strains of Desulfovibrio vulgaris Hildenborough lacking either the sod gene for periplasmic superoxide dismutase or the rbr gene for rubrerythrin, a cytoplasmic hydrogen peroxide (H 2 O 2 ) reductase, were constructed. Their resistance to oxidative stress was compared to that of the wild-type and of a sor mutant lacking the gene for the cytoplasmic superoxide reductase. The sor mutant was more sensitive to exposure to air or to internally or externally generated superoxide than was the sod mutant, which was in turn more sensitive than the wild-type strain. No obvious oxidative stress phenotype was found for the rbr mutant, indicating that H 2 O 2 resistance may also be conferred by two other rbr genes in the D. vulgaris genome.

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“…5). It is noteworthy that the presence of a membrane-targeted MnSOD both in the cytosol and in the periplasm is not unique to Anabaena 7120 but has been reported earlier for Aeromonas hydrophila also [11]. Such membrane targeting, processing and maturation of multiple molecular active MnSOD forms appears to be vital to the survival of the photosynthetic diazotroph Anabaena, as evidenced by severe growth inhibition observed in mutants arrested in MnSOD processing.…”

Section: Discussionmentioning

confidence: 65%

N‐terminal processing of membrane‐targeted MnSOD and formation of multiple active superoxide dismutase dimers in the nitrogen‐fixing cyanobacterium Anabaena sp. strain PCC7120

2013

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Anabaena sp. strain PCC7120 expresses a 30 kDa manganese‐dependent superoxide dismutase (MnSOD) comprising a hydrophobic region (signal peptide + linker peptide) attached to a catalytic unit. Bioinformatics predicted cleavage of the signal peptide at 25CQPQ by signal peptidase and of the linker peptide by an Arg‐C‐like protease at the Arg52/Arg59 residue. The three predicted forms of MnSOD were immunodetected in Anabaena, with the 30 kDa MnSOD found exclusively in the membrane and the shorter 27 and 24 kDa forms found both in the membrane and soluble fractions. The corresponding sodA gene was truncated for (a) the first eight residues, or, (b) the signal peptide, or (c) the entire hydrophobic region, or (d) the Arg52/Arg59 residues were modified to serine. Overexpression of these MnSOD variants in recombinant Anabaena strains revealed that (a) the 30 kDa membrane‐targeted MnSOD was cleaved by membrane‐localized signal peptidase either during or after its transport through the membrane to release the 27 kDa form, either in the cytosol or in the periplasmic/thylakoid lumen, (b) the 27 kDa form was further cleaved to the 24 kDa form by Arg‐C‐like protease, both in the cytosol and in the periplasmic/thylakoid lumen, (c) deletion of signal peptide localized the MnSOD forms in the cytosol, and (d) alteration of the signal/linker peptide cleavage sites interfered with MnSOD localization and processing. Homo/heterodimerization of the 24 and 27 kDa forms of MnSOD and the cytosolic iron‐dependent SOD results in multiple SOD activities, from a single MnSOD gene (sodA), in different cellular compartments of Anabaena.

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Occurrence of two superoxide dismutases in Aeromonas hydrophila: molecular cloning and differential expression of the sodA and sodB genes

Cited by 15 publications

References 31 publications

Battles with Iron: Manganese in Oxidative Stress Protection

Battles with Iron: Manganese in Oxidative Stress Protection

Function of Oxygen Resistance Proteins in the Anaerobic, Sulfate-Reducing Bacterium Desulfovibrio vulgaris Hildenborough

N‐terminal processing of membrane‐targeted MnSOD and formation of multiple active superoxide dismutase dimers in the nitrogen‐fixing cyanobacterium Anabaena sp. strain PCC7120

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