Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/109139
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Type: Journal article
Title: Maize NPF6 proteins are homologs of Arabidopsis CHL1 that are selective for both nitrate and chloride
Other Titles: NPF nitrate and chloride transport
Author: Wen, Z.
Tyerman, S.
Dechorgnat, J.
Ovchinnikova, E.
Dhugga, K.
Kaiser, B.
Citation: The Plant Cell, 2017; 29(9):00724
Publisher: American Society of Plant Biologists
Issue Date: 2017
ISSN: 1040-4651
1532-298X
Statement of
Responsibility: 
Zhengyu Wen, Stephen Tyerman, Julie Dechorgnat, Evgenia Ovchinnikova, Kanwarpal Dhugga, Brent N Kaiser
Abstract: Nitrate uptake by plant cells requires both high and low-affinity transport activities. Arabidopsis (Arabidopsis thaliana, At) nitrate transporter 1/peptide transporter family (NPF) 6.3 is a dual-affinity plasma membrane transport protein that has both high and low-affinity functions. At-NPF6.3 imports and senses nitrate and is regulated by phosphorylation at Thr-101 (T101). A detailed functional analysis of two maize (Zea mays, Zm) homologs of At-NPF6.3 (Zm-NPF6.6 and Zm-NPF6.4) showed that Zm-NPF6.6 was a pH dependent non-biphasic high-affinity nitrate-specific transport protein. By contrast, maize NPF6.4 was a low-affinity nitrate transporter with efflux activity. When supplied chloride, NPF6.4 switched to a high-affinity chloride selective transporter, while NPF6.6 had only a low-affinity chloride transport activity. Structural predictions identified a nitrate binding His (H362) in NPF6.6 but not in NPF6.4. Mutation of NPF6.4 Tyr-370 to His (Y370H) resulted in saturable high-affinity nitrate transport activity and nitrate selectivity. Loss of H362 in NPF6.6 (H362Y) eliminated both nitrate and chloride transport. Furthermore, alterations to Thr-104, a conserved phosphorylation site in NPF6.6, resulted in a similar high-affinity nitrate transport activity with increased Km whereas equivalent changes in NPF6.4 (T106) disrupted high-affinity chloride transport activity. NPF6 proteins exhibit different substrate specificity in plants and regulate nitrate transport affinity/selectivity using a conserved His residue.
Keywords: Arabidopsis; Zea mays; Chlorides; Nitrates; Anion Transport Proteins; Plant Proteins; Gene Expression Regulation, Plant
Rights: © 2017 American Society of Plant Biologists. All rights reserved.
RMID: 0030075443
DOI: 10.1105/tpc.16.00724
Grant ID: http://purl.org/au-research/grants/arc/LP110200878
Appears in Collections:Biochemistry publications

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