Characterization of a novel gene involved in cadmium accumulation screened from sponge-associated bacterial metagenome.
Metagenome research has brought much attention for the identification of important and novel genes of industrial and pharmaceutical value. Here, using a metagenome library constructed from bacteria associated with the marine sponge, Styllisa massa, a high-throughput screening technique using radioisotope was implemented to screen for cadmium (Cd) binding or accumulation genes. From a total of 3301 randomly selected clones, a clone 247-11C was identified as harboring an open reading frame (ORF) showing Cd accumulation characteristics. The ORF, termed as ORF5, was further analyzed by protein functional studies to reveal the presence of a protein, Cdae-1. Cdae-1, composed of a signal peptide and domain harboring an E(G/A)KCG pentapeptide motif, enhanced Cd accumulation when expressed in Escherichia coli. Although showing no direct binding to Cd in vitro, the presence of important amino acid residues related to Cd detoxification suggests that Cdae-1 may possess a different mechanism from known Cd binding proteins such as metallothioneins (MTs) and phytochelatins (PCs). In summary, using the advantage of bacterial metagenomes, our findings in this work suggest the first report on the identification of a unique protein involved in Cd accumulation from bacteria associated with a marine sponge.
Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
Tetsushi
T
Mori
Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan.
Koji
K
Iwamoto
Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
Satoshi
S
Wakaoji
Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan.
Hiroya
H
Araie
Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
Yotaro
Y
Kohara
Faculty of Science and Engineering, Waseda University, Tokyo, Japan.
Yoshiko
Y
Okamura
Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan.
Yoshihiro
Y
Shiraiwa
Faculty of Science and Engineering, Waseda University, Tokyo, Japan. Electronic address: haruko-takeyama@waseda.jp.
Haruko
H
Takeyama
D000595:Amino Acid Sequence; D001483:Base Sequence; D002104:Cadmium / Q000378:metabolism*; D016680:Genome, Bacterial; D054892:Metagenome; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D002104:Cadmium
Cd accumulation; Pentapeptide motif; Sponge-associated bacterial metagenome