Bioinformatic and expression analyses of genes mediating zinc homeostasis in Nostoc punctiforme.
Zinc homeostasis was investigated in Nostoc punctiforme. Cell tolerance to Zn(2+) over 14 days showed that ZnCl(2) levels above 22 microM significantly reduced cell viability. After 3 days in 22 microM ZnCl(2), ca. 12% of the Zn(2+) was in an EDTA-resistant component, suggesting an intracellular localization. Zinquin fluorescence was detected within cells exposed to concentrations up to 37 microM relative to 0 microM treatment. Radiolabeled (65)Zn showed Zn(2+) uptake increased over a 3-day period, while efflux occurred more rapidly within a 3-h time period. Four putative genes involved in Zn(2+) uptake and efflux in N. punctiforme were identified: (i) the predicted Co/Zn/Cd cation transporter, putative CDF; (ii) the predicted divalent heavy-metal cation transporter, putative Zip; (iii) the ATPase component and Fe/Zn uptake regulation protein, putative Fur; and (iv) an ABC-type Mn/Zn transport system, putative zinc ZnuC, ZnuABC system component. Quantitative real-time PCR indicated the responsiveness of all four genes to 22 microM ZnCl(2) within 3 h, followed by a reduction to below basal levels after 24 h by putative ZIP, ZnuC, and Fur and a reduction to below basal level after 72 h by putative CDF efflux gene. These results demonstrate differential regulation of zinc transporters over time, indicating a role for them in zinc homeostasis in N. punctiforme.
Hudek
Lee
L
Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia.
Rai
L C
LC
Freestone
David
D
Michalczyk
Agnes
A
Gibson
Maria
M
Song
Y F
YF
Ackland
M Leigh
ML
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D019295:Computational Biology; D020869:Gene Expression Profiling; D006706:Homeostasis; D050296:Microbial Viability; D046937:Nostoc / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015032:Zinc / Q000378:metabolism* / Q000633:toxicity
D001426:Bacterial Proteins; D002352:Carrier Proteins; D015032:Zinc