Mutation inscoaffects cytochromecassembly and alters oxidative stress resistance inAgrobacterium tumefaciens

Saenkham, Panatda; Vattanaviboon, Paiboon; Mongkolsuk, Skorn

doi:10.1111/j.1574-6968.2009.01516.x

Cited by 14 publications

(7 citation statements)

References 37 publications

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“…All of these results are consistent with the purported role of the eukaryotic (i.e. mitochondrial) ScoI-like proteins (19,22,71,72) and some prokaryotic ScoI homologs (20,23,73) in the biogenesis of the membrane-peripheral, Cu A -containing subunit II domain. Akin to Cox11/CtaG/CoxG, however, the direct transfer of copper from the ScoI chaperone to the target subunit remains to be demonstrated experimentally.…”

Section: Discussionsupporting

confidence: 88%

Disparate Pathways for the Biogenesis of Cytochrome Oxidases in Bradyrhizobium japonicum

Bühler

Rossmann

Landolt

et al. 2010

Journal of Biological Chemistry

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This work addresses the biogenesis of heme-copper terminal oxidases in Bradyrhizobium japonicum, the nitrogen-fixing root nodule symbiont of soybean. B. japonicum has four quinol oxidases and four cytochrome oxidases. The latter include the aa 3 -and cbb 3 -type oxidases. Although both have a Cu B center in subunit I, the subunit II proteins differ in having either a Cu A center (in aa 3 ) or a covalently bound heme c (in cbb 3 ). Two biogenesis factors were genetically studied here, the periplasmically exposed CoxG and ScoI proteins, which are the respective homologs of the mitochondrial copper-trafficking chaperones Cox11 and Sco1 for the formation of the Cu B center in subunit I and the Cu A center in subunit II of cytochrome aa 3 . We could demonstrate copper binding to ScoI in vitro, a process for which the thiols of cysteine residues 74 and 78 in the ScoI polypeptide were shown to be essential. Knock-out mutations in the B. japonicum coxG and scoI genes led to loss of cytochrome aa 3 assembly and activity in the cytoplasmic membrane, whereas the cbb 3 -type cytochrome oxidase apparently remained unaffected. This suggests that subunit I of the cbb 3 -type oxidase obtains its copper cofactor via a different pathway than cytochrome aa 3 . In contrast to the coxG mutation, the scoI mutation caused a decreased symbiotic nitrogen fixation activity. We hypothesize that a periplasmic B. japonicum protein other than any of the identified Cu A proteins depends on ScoI and is required for an effective symbiosis.

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Section: Discussionsupporting

confidence: 88%

Disparate Pathways for the Biogenesis of Cytochrome Oxidases in Bradyrhizobium japonicum

Bühler

Rossmann

Landolt

et al. 2010

Journal of Biological Chemistry

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“…protein shares 33% and 37% amino acid identity with SenC of R. capsulatus and PrrC of R. sphaeroides, respectively ( Fig. 1), including the conserved CxxxC domain and the conserved His-173, which form a copper-binding domain (Eraso & Kaplan, 2000;Nittis et al, 2001;Saenkham et al, 2009). SCO1, PrrC, SenC and SenC P.a.…”

Section: Resultsmentioning

confidence: 99%

“…A recent study (Saenkham et al ., 2009), which was published during the preparation of this manuscript, shows that the SenC homologue of Agrobacterium tumefaciens delivers Cu ions to the terminal oxidases reacting with TMPD (likely of the aa 3 ‐ and cbb 3 ‐types) and that mutations in the conserved Cys71, Cys75 and His163 residues in this Cu chaperone abolish its function. The corresponding Cys84, Cys88 and His173 residues of SenC P.a.…”

Section: Discussionmentioning

confidence: 98%

Copper acquisition by the SenC protein regulates aerobic respiration inPseudomonas aeruginosaâPAO1

Frangipani

Haas

2009

FEMS Microbiology Letters

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Aerobic respiration of Pseudomonas aeruginosa involves four terminal oxidases belonging to the heme-copper family (that is, three cytochrome c oxidases and one quinol oxidase) plus one copper-independent, cyanide-insensitive quinol oxidase (CIO). The PA0114 gene encoding an SCO1/SenC-type protein, which is known to be important for copper delivery to cytochrome c in yeast, Rhodobacter spp. and Agrobacterium tumefaciens, was found to be important for copper acquisition and aerobic respiration in P. aeruginosa. A PA0114 (senC) mutant grew poorly in low-copper media and had low cytochrome cbb(3)-type oxidase activity, but expressed CIO at increased levels, by comparison with the wild-type PAO1. Addition of copper reversed these phenotypes, suggesting that periplasmic copper capture by the SenC protein helps P. aeruginosa to adapt to copper deprivation.

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“…Cytochrome c oxidase activity was spectrophotometrically measured as previously described [35]. One unit of cytochrome c oxidase activity is defined as the amount of enzyme required to oxidize 1 µmol ferrocytochrome c min −1 at 25°C, pH 7.0.…”

Section: Methodsmentioning

confidence: 99%

The Iron-Sulphur Cluster Biosynthesis Regulator IscR Contributes to Iron Homeostasis and Resistance to Oxidants in Pseudomonas aeruginosa

et al. 2014

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IscR is a global transcription regulator responsible for governing various physiological processes during growth and stress responses. The IscR-mediated regulation of the Pseudomonas aeruginosa isc operon, which is involved in iron-sulphur cluster ([Fe-S]) biogenesis, was analysed. The expression of iscR was highly induced through the exposure of the bacteria to various oxidants, such as peroxides, redox-cycling drugs, intracellular iron-chelating agents, and high salts. Two putative type 1 IscR-binding sites were found around RNA polymerase recognition sites, in which IscR-promoter binding could preclude RNA polymerase from binding to the promoter and resulting in repression of the isc operon expression. An analysis of the phenotypes of mutants and cells with altered gene expression revealed the diverse physiological roles of this regulator. High-level IscR strongly inhibited anaerobic, but not aerobic, growth. iscR contributes significantly to the bacteria overall resistance to oxidative stress, as demonstrated through mutants with increased sensitivity to oxidants, such as peroxides and redox-cycling drugs. Moreover, the regulator also plays important roles in modulating intracellular iron homeostasis, potentially through sensing the levels of [Fe-S]. The increased expression of the isc operon in the mutant not only diverts iron away from the available pool but also reduces the total intracellular iron content, affecting many iron metabolism pathways leading to alterations in siderophores and haem levels. The diverse expression patterns and phenotypic changes of the mutant support the role of P. aeruginosa IscR as a global transcriptional regulator that senses [Fe-S] and directly represses or activates the transcription of genes affecting many physiological pathways.

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Mutation inscoaffects cytochromecassembly and alters oxidative stress resistance inAgrobacterium tumefaciens

Cited by 14 publications

References 37 publications

Disparate Pathways for the Biogenesis of Cytochrome Oxidases in Bradyrhizobium japonicum

Disparate Pathways for the Biogenesis of Cytochrome Oxidases in Bradyrhizobium japonicum

Copper acquisition by the SenC protein regulates aerobic respiration inPseudomonas aeruginosaâPAO1

The Iron-Sulphur Cluster Biosynthesis Regulator IscR Contributes to Iron Homeostasis and Resistance to Oxidants in Pseudomonas aeruginosa

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Mutation inscoaffects cytochromecassembly and alters oxidative stress resistance inAgrobacterium tumefaciens

Cited by 14 publications

References 37 publications

Disparate Pathways for the Biogenesis of Cytochrome Oxidases in Bradyrhizobium japonicum

Disparate Pathways for the Biogenesis of Cytochrome Oxidases in Bradyrhizobium japonicum

Copper acquisition by the SenC protein regulates aerobic respiration inPseudomonas aeruginosaâPAO1

The Iron-Sulphur Cluster Biosynthesis Regulator IscR Contributes to Iron Homeostasis and Resistance to Oxidants in Pseudomonas aeruginosa

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Copper acquisition by the SenC protein regulates aerobic respiration inPseudomonas aeruginosaâPAO1