title: Structural implications for heavy metal-induced reversible assembly and aggregation of a protein: the case of Pyrococcus horikoshii CutA.
abstract: CutA is a small protein that appears to be involved in the mechanism of divalent metal cation tolerance in microorganisms. Here we report the crystal structure of Pyrococcus horikoshii CutA (PhoCutA), with and without Cu(2+), and its metal-binding properties. Crystallographic analyses revealed that PhoCutA forms a stable trimeric structure with intertwined antiparallel beta-strands. The crystal structure of the Cu(2+)-PhoCutA complex shows that the Cu(2+) is located at a trimer-trimer interface and is recognized by the side chains of one Asp(48) from each trimer. In an in vitro experiment, PhoCutA bound to several heavy metals, most of which led to reversible aggregation of the protein; i.e. the aggregates could be completely solubilized by addition of ethylenediamine tetraacetic acid (EDTA) or dialysis against metal free buffer. Substitution of Asp(48) with Ala led to a decrease in the amount of aggregates, suggesting the significant contribution of Asp(48) to the reversible aggregation. To the best of our knowledge, this is the first report which provides the structural evidence for heavy metal-induced multimerization of a protein.
authors.affiliation: Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aoba-yama 07, Aoba-ku, 980-8579, Sendai, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Kouhei
authors.initials: K
authors.lastname: Tsumoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yasutake
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakai
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
authors.forename: Izumi
authors.initials: I
authors.lastname: Kumagai
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D019281:Dimerization; D019216:Metals, Heavy / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D043902:Pyrococcus horikoshii / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
chemical_list: D019843:Archaeal Proteins; D002352:Carrier Proteins; D019216:Metals, Heavy; D011994:Recombinant Proteins