A metallothionein and CPx-ATPase handle heavy-metal tolerance in the filamentous cyanobacterium Oscillatoria brevis.
A metallothionein (BmtA) and a CPx-ATPase (Bxa1) have been identified and characterized from the cyanobacterium Oscillatoria brevis. Both bmtA and bxa1 expression can be markedly induced in vivo by Zn(2+) or Cd(2+). Over-expression of bmtA or bxa1 in Escherichia coli enhances Zn(2+) and Cd(2+) tolerance in the transformant. Dynamic studies on the expression of two genes showed that the maximum expression of bxa1 induced by Zn(2+) and Cd(2+) was much quicker than that of bmtA, suggesting distinct physiological roles of metallothionein and CPx-ATPase in the handling of surplus metal.
Research Institute for Bioresources, Okayama University, Kurashiki, Okayama 710-0046, Japan. liutong@server.rib.okayama-u.ac.jp
Tong
T
Liu
Susumu
S
Nakashima
Kazunobu
K
Hirose
Yoshiko
Y
Uemura
Mineo
M
Shibasaka
Maki
M
Katsuhara
Kunihiro
K
Kasamo
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002104:Cadmium / Q000494:pharmacology; D000458:Cyanobacteria / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007700:Kinetics; D008668:Metallothionein / Q000235:genetics / Q000502:physiology*; D019216:Metals, Heavy / Q000494:pharmacology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000494:pharmacology
D001426:Bacterial Proteins; D019216:Metals, Heavy; D012333:RNA, Messenger; D002104:Cadmium; D008668:Metallothionein; D000251:Adenosine Triphosphatases; D015032:Zinc