The membrane-bound tetrahaem c-type cytochrome CymA interacts directly with the soluble fumarate reductase in Shewanella

C Schwalb, Stephen K Chapman, Graeme A Reid

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    Abstract

    Shewanella spp. demonstrate great variability in the use of terminal electron acceptors in anaerobic respiration; these include nitrate, fumarate, DMSO, trimethylamine oxide, sulphur com- pounds and metal oxides. These pathways open up possible applications in bioremediation. The wide variety of respiratory substrates for Shewanella is correlated with the evolution of several multi-haem membrane-bound, periplasmic and outer-membrane c-type cytochromes. The 21 kDa c-type cytochrome CymA of the freshwater strain Shewanella oneidensis MR-1 has an N-terminal membrane anchor and a globular tetrahaem periplasmic domain. According to sequence alignments, CymA is a member of the NapC/NirT family. This family of redox proteins is responsible for electron transfer from the quinone pool to periplasmic and outer-membrane-bound reductases. Prior investigations have shown that the absence of CymA results in loss of the ability to respire with Fe(III), fumarate and nitrate, indicating that CymA is involved in electron transfer to several terminal reductases. Here we describe the expression, purification and characterization of a soluble, truncated CymA ('CymA). Potentiometric studies suggest that there are two pairs of haems with potentials of - 175 and - 261 mV and that 'CymA is an efficient electron donor for the soluble fumarate reductase, flavocytochrome c(3).

    Original languageEnglish
    Pages (from-to)658-662
    Number of pages5
    JournalBiochemical Society Transactions
    Volume30
    Issue number4
    DOIs
    Publication statusPublished - Aug 2002
    EventColloquium on Tetrapyrroles: Their Life, Birth and Death - Edinburgh, United Kingdom
    Duration: 8 Apr 200210 Apr 2002

    Keywords

    • BACTERIA
    • SEQUENCE
    • IRON(III)
    • FLAVOCYTOCHROME-C
    • RESPIRATION
    • flavocytochrome c(3)
    • electron transport
    • PUTREFACIENS MR-1
    • OUTER-MEMBRANE
    • NITRATE
    • haem
    • anaerobic respiration
    • truncated CymA

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