A novel histidine-rich CPx-ATPase from the filamentous cyanobacterium Oscillatoria brevis related to multiple-heavy-metal cotolerance

Liu Tong, Susumu Nakashima, Mineo Shibasaka, Maki Katsuhara, Kunihiro Kasamo

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31 Citations (Scopus)


A novel gene related to heavy-metal transport was cloned and identified from the filamentous cyanobacterium Oscillatoria brevis. Sequence analysis of the gene (the Bxal gene) showed that its product possessed high homology with heavy-metal transport CPx-ATPases. The CPC motif, which is proposed to form putative cation transduction channel, was found in the sixth transmembrane helix. However, instead of the CXXC motif that is present in the N termini of most metal transport CPx-ATPases, Bxal contains a unique Cys-Cys (CC) sequence element and histidine-rich motifs as a putative metal binding site. Northern blotting and real-time quantitative reverse transcription-PCR showed that expression of Bxa1 mRNA was induced in vivo by both monovalent (Cu+ and Ag+) and divalent (Zn2+ and Cd2+) heavy-metal ions at similar levels. Experiments on heavy-metal tolerance in Escherichia coli with recombinant Bxal demonstrated that Bxal conferred resistance to both monovalent and divalent heavy metals. This is the first report of a CPx-ATPase responsive to both monovalent and divalent heavy metals.

Original languageEnglish
Pages (from-to)5027-5035
Number of pages9
JournalJournal of bacteriology
Issue number18
Publication statusPublished - Sep 1 2002


ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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