Copper and cadmium: responses in Pseudomonas putida KT2440.
OBJECTIVE
To compare responses of a soil bacterium to Cu and Cd.


RESULTS
In minimal medium, Cd caused a dose-dependent growth stasis of logarithmic phase cells of Pseudomonas putida, strain KT2440, whereas Cu did not compromise growth up to 10 mg l(-1). Proteomics showed changes in accumulation of both membrane and soluble proteins by 6 h of treatment; increased Krebs cycle enzymes were apparent. Transcript analysis showed Cd- and Cu-induced different genes. Cd-induced genes encoding the transcriptional regulator CzrR2; an outer membrane protein associated with lipopolysaccharide stability, H1; two oxidative stress protective proteins and the P-type ATPase, CadA2, associated with Cd(2+) efflux. The genes most responsive to Cu encoded the regulator CopR1 and the outer membrane resistance protein regulated by CopR1, CopB1; a putative porin, PorD and the Cu-binding protein, PacZ or CopZ, and CopA2.


CONCLUSIONS
These findings support that a soil pseudomonad restricts internalization of the metals by using different sets of binding proteins and efflux pumps. Activation of mechanisms to protect against oxidative stress also was evident especially with Cd exposure.


CONCLUSIONS
The differential cellular responses to Cd and Cu suggest that risk assessment for Cd and Cu should be different.
Biological and Irrigation Engineering Department, Utah State University, Logan, 84322-5305, USA.
C D
CD
Miller
B
B
Pettee
C
C
Zhang
M
M
Pabst
J E
JE
McLean
A J
AJ
Anderson
D001426:Bacterial Proteins / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D018384:Oxidative Stress; D020543:Proteome / Q000378:metabolism; D016958:Pseudomonas putida / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012988:Soil Microbiology
D001426:Bacterial Proteins; D020543:Proteome; D012329:RNA, Bacterial; D002104:Cadmium; D003300:Copper