Superoxide Dismutases

Cass, Anthony E. G.

doi:10.1007/978-1-349-06372-7_4

Cited by 20 publications

(12 citation statements)

References 125 publications

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“…To assess how extracellular O 2 − influences growth and physiology, E. huxleyi cultures were grown with a range of SOD concentrations and monitored until the end of exponential phase. Since SOD is a large enzyme (>31 kDa) (Cass, 1985), it cannot passively cross cell membranes and therefore selectively targets O 2 − within the extracellular milieu. Overall, the addition of SOD stimulated growth (Figure 4; Supplementary Figure S2; Supplementary Table S2).…”

Section: Resultsmentioning

confidence: 99%

Dynamic Regulation of Extracellular Superoxide Production by the Coccolithophore Emiliania huxleyi (CCMP 374)

et al. 2019

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In marine waters, ubiquitous reactive oxygen species (ROS) drive biogeochemical cycling of metals and carbon. Marine phytoplankton produce the ROS superoxide (O 2 − ) extracellularly and can be a dominant source of O 2 − in natural aquatic systems. However, the cellular regulation, biological functioning, and broader ecological impacts of extracellular O 2 − production by marine phytoplankton remain mysterious. Here, we explored the regulation and potential roles of extracellular O 2 − production by a noncalcifying strain of the cosmopolitan coccolithophorid Emiliania huxleyi , a key species of marine phytoplankton that has not been examined for extracellular O 2 − production previously. Cell-normalized extracellular O 2 − production was the highest under presumably low-stress conditions during active proliferation and inversely related to cell density during exponential growth phase. Removal of extracellular O 2 − through addition of the O 2 − scavenger superoxide dismutase (SOD), however, increased growth rates, growth yields, cell biovolume, and photosynthetic efficiency ( F v /F m ) indicating an overall physiological improvement. Thus, the presence of extracellular O 2 − does not directly stimulate E. huxleyi proliferation, as previously suggested for other phytoplankton, bacteria, fungi, and protists. Extracellular O 2 − production decreased in the dark, suggesting a connection with photosynthetic processes. Taken together, the tight regulation of this stress independent production of extracellular O 2 − by E. huxleyi suggests that it could be involved in fundamental photophysiological processes.

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Section: Resultsmentioning

confidence: 99%

Dynamic Regulation of Extracellular Superoxide Production by the Coccolithophore Emiliania huxleyi (CCMP 374)

et al. 2019

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“…Histidine residues are known to coordinate Cu+, for example, in small blue copper proteins (azurin), which coordinate Cu+ through two His, one Cys, and one Met (1). Also, the enzyme cuprozinc superoxide dismutase binds Cu+ and Cd2" through the imidazole ring of histidine (7). However, the mutant which was generated accumulated…”

Section: Discussionmentioning

confidence: 99%

Expression of a Neurospora crassa metallothionein and its variants in Escherichia coli

Romeyer

Jacobs

Brousseau

1990

Appl Environ Microbiol

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The Neurospora crassa metallothionein (NC) synthesis gene was cloned and expressed in Escherichia coli in two different expression vectors (pING2 and pUA7), both under the regulation of the Salmonella typhimurium arabinose operon. Upon induction with arabinose, the pING2-NC vector expressed as inclusion body-localized AraB'::NC fusion protein of 21 kilodaltons. The pUA7-NC vector expressed a 5.3-kilodalton Lpp::NC fusion protein anchored to the outer membrane of the cell. Cells expressing the NC fusion proteins accumulated Cd21 and Cu+ (between 2.3and 11-fold) compared with nonexpressing cells. To generate novel forms of metal-binding peptides, a set of specific mutant genes for N. crassa NC was designed in which each cysteine residue was replaced with a subset of amino acids implicated in peptide-metal coordination (Asn, Asp, His, Lys, or Tyr residues). These mutant NC sequences were cloned into the two vectors and expressed in E. coli. One of the mutant proteins (containing His residues) showed accumulation of Cd2' and Cu' (threefold) from a mixture of 16 heavy metals species. None of the other heavy metals present in the culture was accumulated.

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“…Superoxide dismutase (SOD) enzymes are ubiquitous in living systems . These enzymes serve a vital role in defending oxygen-utilizing life forms from oxidative damage .…”

Section: Introductionmentioning

confidence: 99%