Nitrate reductase activity is required for nitrate uptake into fungal but not plant cells

Sheila Eileen Unkles, R Wang, Y Wang, ADM Glass, NM Crawford, James Robertson Kinghorn

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

The ability to transport net nitrate was conferred upon transformant cells of the non-nitrate-assimilating yeast Pichia pastoris after the introduction of two genes, one encoding nitrate reductase and the other nitrate transport. It was observed that cells of this lower eukaryote transformed with the nitrate transporter gene alone failed to display net nitrate transport despite having the ability to produce the protein. In addition, loss-of-function nitrate reductase mutants isolated from several nitrate-assimilating fungi appeared to be unable to accumulate nitrate. Uptake assays using the tracer (NO3-)-N-13 showed that nitrate influx is negligible in cells of a nitrate reductase null mutant. In parallel studies using a higher eukaryotic plant, Arabidopsis thaliana, loss-of-function nitrate reductase strains homozygous for both NIA1 insertion and NIA2 deletion were found to have no detectable nitrate reductase mRNA or nitrate reductase activity but retained the ability to transport nitrate. The reasons for these fundamental differences in nitrate transport into the cells of representative members of these two eukaryotic kingdoms are discussed.

Original languageEnglish
Pages (from-to)28182-28186
Number of pages5
JournalJournal of Biological Chemistry
Volume279
Issue number27
DOIs
Publication statusPublished - 2 Jul 2004

Keywords

  • ASPERGILLUS-NIDULANS
  • ARABIDOPSIS
  • MUTANTS
  • IDENTIFICATION
  • MOLYBDOPTERIN
  • ASSIMILATION
  • TRANSPORTER
  • PROTEINS
  • CHLORATE
  • INVITRO

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