The ZntA-like NpunR4017 plays a key role in maintaining homeostatic levels of zinc in Nostoc punctiforme.
Analysis of cellular response to zinc exposure provides insights into how organisms maintain homeostatic levels of zinc that are essential, while avoiding potentially toxic cytosolic levels. Using the cyanobacterium Nostoc punctiforme as a model, qRT-PCR analyses established a profile of the changes in relative mRNA levels of the ZntA-like zinc efflux transporter NpunR4017 in response to extracellular zinc. In cells treated with 18 μM of zinc for 1 h, NpunR4017 mRNA levels increased by up to 1300 % above basal levels. The accumulation and retention of radiolabelled (65)Zn by NpunR4107-deficient and overexpressing strains were compared to wild-type levels. Disruption of NpunR4017 resulted in a significant increase in zinc accumulation up to 24 % greater than the wild type, while cells overexpressing NpunR4107 accumulated 22 % less than the wild type. Accumulation of (65)Zn in ZntA(-) Escherichia coli overexpressing NpunR4017 was reduced by up to 21 %, indicating the capacity for NpunR4017 to compensate for the loss of ZntA. These findings establish the newly identified NpunR4017 as a zinc efflux transporter and a key transporter for maintaining zinc homeostasis in N. punctiforme.
Centre for Regional and Rural Futures, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia. lhudek@deakin.edu.au.|Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia. lhudek@deakin.edu.au.
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Hudek
Centre for Regional and Rural Futures, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.|School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.
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Bräu
Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.|School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.
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Michalczyk
Australian Centre for Astrobiology and School of Biotechnology and Biological Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
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Neilan
Department of Microbiology, University of California, Davis, CA, 95616, USA.
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Meeks
Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.|School of Life and Environmental Sciences, Deakin University, 221 Burwood Hwy, Burwood, Victoria, 3125, Australia.
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Ackland
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D006706:Homeostasis; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D046937:Nostoc / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D015032:Zinc / Q000378:metabolism*
D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D015032:Zinc
Cyanobacteria; Metal efflux; P-type ATPase; Zinc; Zinc homeostasis; ZntA