title: Zinc uptake, oxidative stress and the FNR-like proteins of Lactococcus lactis.
abstract: Lactococcus lactis ssp. cremoris MG1363 contains two FNR homologues, FlpA and FlpB, encoded by the distal genes of two paralogous operons (orfX(A/B)-orfY(A/B)-flpA/B). An flpA flpB double mutant strain is hypersensitive to hydrogen peroxide and has a depleted intracellular Zn(II) pool. The phenotypes of the flp mutant strains suggest that FlpA and FlpB control the expression of high and low affinity ATP-dependent Zn(II) uptake systems, respectively. Plate tests revealed that expression from a orfX(B)::lac reporter was activated by Cd(II), consistent with other Zn(II)-regulated systems. The link between a failure to acquire Zn(II) and hypersensitivity to oxidative stress suggests that Zn(II) may be required to protect vulnerable protein thiols from oxidation.
authors.affiliation: Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, UK.
authors.forename: C
authors.initials: C
authors.lastname: Scott
authors.forename: H
authors.initials: H
authors.lastname: Rawsthorne
authors.forename: M
authors.initials: M
authors.lastname: Upadhyay
authors.forename: C A
authors.initials: CA
authors.lastname: Shearman
authors.forename: M J
authors.initials: MJ
authors.lastname: Gasson
authors.forename: J R
authors.initials: JR
authors.lastname: Guest
authors.forename: J
authors.initials: J
authors.lastname: Green
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology; D005029:Ethylenediamines / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D002614:Chelating Agents; D005029:Ethylenediamines; C119770:FlpA protein, bacteria; C119771:FlpB protein, Lactococcus lactis; D014157:Transcription Factors; D002104:Cadmium; D000255:Adenosine Triphosphate; D015032:Zinc; C044387:N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine