Discovery of novel secreted fungal sulfhydryl oxidases with a plate test screen

Nivala, Outi; Mattinen, Maija‐Liisa; Faccio, Greta; Büchert, Johanna; Kruus, Kristiina

doi:10.1007/s00253-013-4753-9

Cited by 4 publications

(8 citation statements)

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“…In this work, we focused on a secreted SOX from the fungus A. tubingensis and report the biochemical characterization of the secreted sulfhydryl oxidase AtSOX. A. tubingensis was previously identified as a natural SOX-producing strain [ 28 ]. In addition, we investigated the possible physiological role of SOX enzymes by bioinformatics means, as no clear role has yet been established for secreted fungal SOXs thus far.…”

Section: Discussionmentioning

confidence: 99%

“…Aspergillus tubingensis strain D-85248 was obtained from the VTT Culture Collection [ 29 ] and cultivated as described in [ 28 ]. A. tubingensis was grown on PeptoneTM-D(+)-glucose media adapted from [ 3 , 5 ] in liquid cultivation at 30 °C under shaking (250 rpm).…”

Section: Methodsmentioning

confidence: 99%

“…The spectroscopic measurements were done with a Cary 100 Bio UV-vis spectrophotometer (Varian Inc., Houten, the Netherlands). Second, the oxygen consumption measurement with Fibox 3 PreSens fiber-optic oxygen meter (Presens GmbH, Regensburg, Germany) was used to measure the changes in the concentration of dissolved oxygen during enzymatic reaction as described by [ 28 ]. GSH (5 mM) was used as a substrate when determining AtSOX activity.…”

Section: Methodsmentioning

confidence: 99%

“…This paper reports the biochemical characterization of SOX from A. tubingensis (AtSOX) previously identified in the screening study [ 28 ]. AtSOX was purified and its substrate specificity was further characterized and its activity on different peptide- and protein-bound sulfhydryl groups analysed.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of sulfhydryl oxidase from Aspergillus tubingensis

et al. 2017

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BackgroundDespite of the presence of sulfhydryl oxidases (SOXs) in the secretomes of industrially relevant organisms and their many potential applications, only few of these enzymes have been biochemically characterized. In addition, basic functions of most of the SOX enzymes reported so far are not fully understood. In particular, the physiological role of secreted fungal SOXs is unclear.ResultsThe recently identified SOX from Aspergillus tubingensis (AtSOX) was produced, purified and characterized in the present work. AtSOX had a pH optimum of 6.5, and showed a good pH stability retaining more than 80% of the initial activity in a pH range 4-8.5 within 20 h. More than 70% of the initial activity was retained after incubation at 50 °C for 20 h. AtSOX contains a non-covalently bound flavin cofactor. The enzyme oxidised a sulfhydryl group of glutathione to form a disulfide bond, as verified by nuclear magnetic resonance spectroscopy. AtSOX preferred glutathione as a substrate over cysteine and dithiothreitol. The activity of the enzyme was totally inhibited by 10 mM zinc sulphate. Peptide- and protein-bound sulfhydryl groups in bikunin, gliotoxin, holomycin, insulin B chain, and ribonuclease A, were not oxidised by the enzyme. Based on the analysis of 33 fungal genomes, SOX enzyme encoding genes were found close to nonribosomal peptide synthetases (NRPS) but not with polyketide synthases (PKS). In the phylogenetic tree, constructed from 25 SOX and thioredoxin reductase sequences from IPR000103 InterPro family, AtSOX was evolutionary closely related to other Aspergillus SOXs. Oxidoreductases involved in the maturation of nonribosomal peptides of fungal and bacterial origin, namely GliT, HlmI and DepH, were also evolutionary closely related to AtSOX whereas fungal thioreductases were more distant.ConclusionsAtSOX (55 kDa) is a fungal secreted flavin-dependent enzyme with good stability to both pH and temperature. A Michaelis-Menten behaviour was observed with reduced glutathione as a substrate. Based on the location of SOX enzyme encoding genes close to NRPSs, SOXs could be involved in the secondary metabolism and act as an accessory enzyme in the production of nonribosomal peptides.Electronic supplementary materialThe online version of this article (10.1186/s12858-017-0090-4) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of sulfhydryl oxidase from Aspergillus tubingensis

et al. 2017

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“…A number of secreted fungal flavin-linked sulfhydryl oxidases 267–270 are efficient catalysts of the oxidation of glutathione: 267,268…”

Section: How Enzymes Contribute To Thiol Oxidation Reactionsmentioning

confidence: 99%

Chemistry and Enzymology of Disulfide Cross-Linking in Proteins

2017

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Cysteine thiols are among the most reactive functional groups in proteins, and their pairing in disulfide linkages is a common post-translational modification in proteins entering the secretory pathway. This modest amino acid alteration, the mere removal of a pair of hydrogen atoms from juxtaposed cysteine residues, contrasts with the substantial changes that characterize most other post-translational reactions. However, the wide variety of proteins that contain disulfides, the profound impact of cross-linking on the behavior of the protein polymer, the numerous and diverse players in intracellular pathways for disulfide formation, and the distinct biological settings in which disulfide bond formation can take place belie the simplicity of the process. Here we lay the groundwork for appreciating the mechanisms and consequences of disulfide bond formation in vivo by reviewing chemical principles underlying cysteine pairing and oxidation. We then show how enzymes tune redox-active cofactors and recruit oxidants to improve the specificity and efficiency of disulfide formation. Finally, we discuss disulfide bond formation in a cellular context and identify important principles that contribute to productive thiol oxidation in complex, crowded, dynamic environments.

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Characterization of recombinant rice quiescin sulfhydryl oxidase and its improvement effect on wheat flour-processing quality

Wei

Deng

et al. 2020

Food Chemistry

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Discovery of novel secreted fungal sulfhydryl oxidases with a plate test screen

Cited by 4 publications

References 23 publications

Characterization of sulfhydryl oxidase from Aspergillus tubingensis

Characterization of sulfhydryl oxidase from Aspergillus tubingensis

Chemistry and Enzymology of Disulfide Cross-Linking in Proteins

Characterization of recombinant rice quiescin sulfhydryl oxidase and its improvement effect on wheat flour-processing quality

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