Geobacillus stearothermophilus V ubiE gene product is involved in the evolution of dimethyl telluride in Escherichia coli K-12 cultures amended with potassium tellurate but not with potassium tellurite.
A 3.8-kb fragment of chromosomal DNA of Geobacillus stearothermophilus V cloned in pSP72 (p1VH) confers resistance to potassium tellurite (K(2)TeO(3)) and to potassium tellurate (K(2)TeO(4)) when the encoded genes are expressed in Escherichia coli K-12. The nt sequence of the cloned fragment predicts three ORFs of 780, 399, and 600 bp, whose encoded protein products exhibit about 80% similarity with the SUMT methyltransferase and the BtuR protein of Bacillus megaterium, and with the UbiE methyltransferase of Bacillus anthracis A2012, respectively. In addition, E. coli/p1VH cells evolved dimethyl telluride, which was released into the headspace gas above liquid cultures when amended with K(2)TeO(3) or with K(2)TeO(4). After 48 h of growth in the presence of these compounds, a protein of about 25 kDa was found at a significantly higher level when crude extracts were analyzed by SDS-PAGE. The N-terminal amino acid (aa) sequence of this protein, obtained by Edman degradation, matched the deduced aa sequence predicted by the G. stearothermophilus V ubiE gene. This gene was amplified by PCR, subcloned in pET21b, and transformed into E. coli JM109(DE3). Interestingly, DMTe evolution occurred when these modified cells were grown in K(2)TeO(4) - but not in K(2)TeO(3) - amended media. These results may be indicative that the two Te oxyanions could be detoxified in the cell by different metabolic pathways.
Araya
Manuel A
MA
Laboratorio de Microbiología Molecular, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile.
Swearingen
Jerry W
JW
Plishker
Mary F
MF
Saavedra
Claudia P
CP
Chasteen
Thomas G
TG
Vásquez
Claudio C
CC
D000838:Anions / Q000737:chemistry; D001406:Bacillaceae / Q000737:chemistry*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002875:Chromosomes / Q000235:genetics; D003470:Culture Media; D004247:DNA / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D048168:Escherichia coli K12 / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013691:Tellurium / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D013997:Time Factors
D000838:Anions; D001426:Bacterial Proteins; D003470:Culture Media; C088869:dimethyltelluride; C026899:potassium tellurate(IV); D004247:DNA; D013691:Tellurium