title: Characterization of two cation diffusion facilitators NpunF0707 and NpunF1794 in Nostoc punctiforme.
abstract: OBJECTIVE
  To characterize genes involved in maintaining homeostatic levels of zinc in the cyanobacterium Nostoc punctiforme.
  
  
  RESULTS
  Metal efflux transporters play a central role in maintaining homeostatic levels of trace elements such as zinc. Sequence analyses of the N. punctiforme genome identified two potential cation diffusion facilitator (CDF) metal efflux transporters, Npun_F0707 (Cdf31) and Npun_F1794 (Cdf33). Deletion of either Cdf31or Cdf33 resulted in increased zinc retention over 3 h. Interestingly, Cdf31(-) and Cdf33(-) mutants showed no change in sensitivity to zinc exposure in comparison with the wild type, suggesting some compensatory capacity for the loss of each other. Using qRT-PCR, a possible interaction was observed between the two cdf's, where the Cdf31(-) mutant had a more profound effect on cdf33 expression than Cdf33(-) did on cdf31. Over-expression of Cdf31 and Cdf33 in ZntA(-) - and ZitB(-) -deficient Escherichia coli revealed function similarities between the ZntA and ZitB of E. coli and the cyanobacterial transporters.
  
  
  CONCLUSIONS
  The data presented shed light on the function of two important transporters that regulate zinc homeostasis in N. punctiforme.
  
  
  CONCLUSIONS
  This study shows for the first time the functional characterization of two cyanobacterial zinc efflux proteins belonging to the CDF family.
authors: Centre for Regional and Rural Futures, Deakin University, Burwood, Melbourne, Vic., Australia.|Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia.
authors: L
authors: L
authors: Hudek
authors: Australian Centre for Astrobiology and School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW, Australia.
authors: L
authors: L
authors: Pearson
authors: Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia.
authors: A A
authors: AA
authors: Michalczyk
authors: Centre for Regional and Rural Futures, Deakin University, Burwood, Melbourne, Vic., Australia.|Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia.
authors: L
authors: L
authors: Bräu
authors: Australian Centre for Astrobiology and School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW, Australia.
authors: B A
authors: BA
authors: Neilan
authors: Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Vic., Australia.
authors: M L
authors: ML
authors: Ackland
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D026901:Membrane Transport Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D046937:Nostoc / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D015032:Zinc
keywords: Cyanobacteria; cation diffusion facilitator; metal efflux; zinc; zinc homeostasis