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http://purl.uniprot.org/citations/9593308http://www.w3.org/1999/02/22-rdf-syntax-ns#typehttp://purl.uniprot.org/core/Journal_Citation
http://purl.uniprot.org/citations/9593308http://www.w3.org/1999/02/22-rdf-syntax-ns#typehttp://purl.uniprot.org/core/Journal_Citation
http://purl.uniprot.org/citations/9593308http://www.w3.org/2000/01/rdf-schema#comment"Cytochrome c552 is the terminal component of the formate-dependent nitrite reduction pathway of Escherichia coli. In addition to four 'typical' haem-binding motifs, CXXCH-, characteristic of c-type cytochromes, the N-terminal region of NrfA includes a motif, CWSCK. Peptides generated by digesting the cytochrome from wild-type bacteria with cyanogen bromide followed by trypsin were analysed by on-line HPLC MS/MS in parent scanning mode. A strong signal at mass 619, corresponding to haem, was generated by fragmentation of a peptide of mass 1312 that included the sequence CWSCK. Neither this signal nor the haem-containing peptide of mass 1312 was detected in parallel experiments with cytochrome that had been purified from a transformant unable to synthesize NrfE, NrfF and NrfG: this is consistent with our previous report that NrfE and NrfG (but not NrfF) are essential for formate-dependent nitrite reduction. Redox titrations clearly revealed the presence of high and low mid-point potential redox centres. The best fit to the experimental data is for three n=1 components with mid-point redox potentials (pH 7.0) of +45 mV (21% of the total absorbance change), -90 mV (36% of the total) and -210mV (43% of the total). Plasmids in which the lysine codon of the cysteine-lysine motif, AAA, was changed to the histidine codon CAT (to create a fifth 'typical' haem c-binding motif), or to the isoleucine and leucine codons, ATT and CTT, were unable to transform a Nrf deletion mutant to Nrf+ or to restore formate-dependent nitrite reduction to the transformants. The presence of a 50 kDa periplasmic c-type cytochrome was confirmed by staining proteins separated by SDS-PAGE for covalently bound haem, but the methyl-viologen-dependent nitrite reductase activities associated with the mutated proteins, although still detectable, were far lower than that of the native protein. The combined data establish not only that there is a haem group bound covalently to the cysteine-lysine motif of cytochrome c552 but also that one or more products of the last three genes of the nrf operon are essential for the haem ligation to this motif."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.org/dc/terms/identifier"doi:10.1046/j.1365-2958.1998.00792.x"xsd:string
http://purl.uniprot.org/citations/9593308http://purl.org/dc/terms/identifier"doi:10.1046/j.1365-2958.1998.00792.x"xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Cole J.A."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Cole J.A."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"James P."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"James P."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Poole R.K."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Poole R.K."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Staudenmann W."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Staudenmann W."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"White S.A."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"White S.A."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Eaves D.J."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Eaves D.J."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Grove J."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Grove J."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Griffiths I."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/author"Griffiths I."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/date"1998"xsd:gYear
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/date"1998"xsd:gYear
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/name"Mol. Microbiol."xsd:string
http://purl.uniprot.org/citations/9593308http://purl.uniprot.org/core/name"Mol. Microbiol."xsd:string
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