Affiliation:
1. Département de Microbiologie Fondamentale, Université de Lausanne, CH-1015 Lausanne
2. Environmental Biophysical Chemistry, Ecole Polytechnique Fédérale, Station 2, CH-1015 Lausanne, Switzerland
Abstract
ABSTRACT
Restricted bioavailability of copper in certain environments can interfere with cellular respiration because copper is an essential cofactor of most terminal oxidases. The global response of the metabolically versatile bacterium and opportunistic pathogen
Pseudomonas aeruginosa
to copper limitation was assessed under aerobic conditions. Expression of
cioAB
(encoding an alternative, copper-independent, cyanide-resistant ubiquinol oxidase) was upregulated, whereas numerous iron uptake functions (including the siderophores pyoverdine and pyochelin) were expressed at reduced levels, presumably reflecting a lower demand for iron by respiratory enzymes. Wild-type
P. aeruginosa
was able to grow aerobically in a defined glucose medium depleted of copper, whereas a
cioAB
mutant did not grow. Thus,
P. aeruginosa
relies on the CioAB enzyme to cope with severe copper deprivation. A quadruple
cyo cco1 cco2 cox
mutant, which was deleted for all known heme-copper terminal oxidases of
P. aeruginosa
, grew aerobically, albeit more slowly than did the wild type, indicating that the CioAB enzyme is capable of energy conservation. However, the expression of a
cioA
′-′
lacZ
fusion was less dependent on the copper status in the quadruple mutant than in the wild type, suggesting that copper availability might affect
cioAB
expression indirectly, via the function of the heme-copper oxidases.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology