title: Marinobacter adhaerens HP15 harbors two CzcCBA efflux pumps involved in zinc detoxification.
abstract: Several members of the ubiquitously found γ-proteobacterial genus Marinobacter were described or assumed to inhabit marine environments naturally enriched in heavy metals. However, direct studies that describe the ability of this genus to occupy such environments have not been conducted. To cope with heavy metal stress, bacteria possess specific efflux pumps as tools for detoxification, among which the CzcCBA type efflux system is one representative. Previous studies showed that this system plays an important role in resistance towards cadmium, zinc, and cobalt. Up to now, no study had focused on characterization of Czc pumps in Marinobacter sp. or other marine prokaryotes. Herein, we elucidated the function of two CzcCBA pumps encoded by Marinobacter adhaerens HP15's genome during exposure to cadmium, zinc, and cobalt. Single and double knock-out mutants lacking the corresponding two czcCBA operons were generated and analyzed in terms of their resistance profiles. Both operons appeared to be important for zinc resistance but had no role in tolerance towards cadmium or cobalt. One of the mutations was genetically complemented thereby restoring the wild type phenotype. In accordance with the resistance pattern, expression of the genes coding for both CzcCBA pumps was induced by zinc but neither by cadmium nor cobalt.
authors.affiliation: Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Stahl
authors.forename: Daniel
authors.initials: D
authors.lastname: Pletzer
authors.forename: Amna
authors.initials: A
authors.lastname: Mehmood
authors.forename: Matthias S
authors.initials: MS
authors.lastname: Ullrich
mesh_terms: D001693:Biological Transport, Active; D002104:Cadmium / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005816:Genetic Complementation Test; D053520:Marinobacter / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009876:Operon; D015533:Transcriptional Activation / Q000187:drug effects; D015032:Zinc / Q000378:metabolism*
chemical_list: D026901:Membrane Transport Proteins; D002104:Cadmium; D003035:Cobalt; D015032:Zinc