Isolation of a novel Thermus thermophilus metal efflux protein that improves Escherichia coli growth under stress conditions.
The mechanisms of metal ion transport in thermophilic organisms are poorly understood. Phage display-based screening of a Thermus thermophilus genomic library in Escherichia coli led to the identification of a novel metal cation efflux protein. The Thermus protein showed extensive sequence and putative structural conservation to Czr and Czc proteins in mesophilic bacterial and mammalian species. Expression of the gene in E. coli led to increased resistance to zinc and cadmium ions, but not to cobalt, in an effect that was apparently caused by increased efflux of metals from the cell. This increased resistance was inducible by zinc and cadmium and, to a lesser extent, by cobalt. Furthermore, E. coli cells containing the Thermus gene exhibited improved cell physiology and delayed cell lysis during recombinant protein production, leading to accumulation of higher levels of recombinant protein. The molecular basis and potential application of the findings are discussed.
Spada
Stefania
S
Department of Chemical and Environmental Sciences, University of Limerick, Plassey Technological Park, Limerick, Ireland.
Pembroke
J Tony
JT
Wall
J Gerard
JG
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000254:growth & development*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus / Q000378:metabolism*
D001426:Bacterial Proteins; C120279:CzrB protein, bacteria; D017931:DNA Primers; D008565:Membrane Proteins