title: An efflux transporter PbrA and a phosphatase PbrB cooperate in a lead-resistance mechanism in bacteria.
abstract: The gene cluster pbrTRABCD from Cupriavidus metallidurans CH34 is thought to encode a unique, specific resistance mechanism for lead. However, the exact functions of these genes are unknown. In this study we examine the metal specificity and functions of pbrABCD by expressing these genes in different combinations and comparing their ability to restore Pb(2+), Zn(2+) and Cd(2+) resistance in a metal-sensitive C. metallidurans strain DN440. We show that lead resistance in C. metallidurans is achieved through the cooperation of the Zn/Cd/Pb-translocating ATPase PbrA and the undecaprenyl pyrophosphate phosphatase PbrB. While PbrA non-specifically exported Pb(2+), Zn(2+) and Cd(2+), a specific increase in lead resistance was observed when PbrA and PbrB were coexpressed. As a model of action for PbrA and PbrB we propose a mechanism where Pb(2+) is exported from the cytoplasm by PbrA and then sequestered as a phosphate salt with the inorganic phosphate produced by PbrB. Similar operons containing genes for heavy metal translocating ATPases and phosphatases were found in several different bacterial species, suggesting that lead detoxification through active efflux and sequestration is a common lead-resistance mechanism.
authors.affiliation: Department of Applied Chemistry and Microbiology, University of Helsinki, FIN-00014 Helsinki, Finland.
authors.forename: Anu
authors.initials: A
authors.lastname: Hynninen
authors.forename: Thierry
authors.initials: T
authors.lastname: Touzé
authors.forename: Leena
authors.initials: L
authors.lastname: Pitkänen
authors.forename: Dominique
authors.initials: D
authors.lastname: Mengin-Lecreulx
authors.forename: Marko
authors.initials: M
authors.lastname: Virta
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D049921:Cupriavidus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D007854:Lead / Q000494:pharmacology*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D009876:Operon; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D007854:Lead; D000251:Adenosine Triphosphatases; D011755:Pyrophosphatases; C503879:undecaprenyl pyrophosphate phosphatase