A PII-like protein in <i>Arabidopsis</i> : Putative role in nitrogen sensing

DOI Web Site 13 Citations
  • Ming-Hsiun Hsieh
    Department of Biology, New York University, New York, NY 10003; Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; and CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
  • Hon-Ming Lam
    Department of Biology, New York University, New York, NY 10003; Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; and CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
  • Frank J. van de Loo
    Department of Biology, New York University, New York, NY 10003; Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; and CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia
  • Gloria Coruzzi
    Department of Biology, New York University, New York, NY 10003; Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; and CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia

Abstract

<jats:p> PII is a protein allosteric effector in <jats:italic>Escherichia coli</jats:italic> and other bacteria that indirectly regulates glutamine synthetase at the transcriptional and post-translational levels in response to nitrogen availability. Data supporting the notion that plants have a nitrogen regulatory system(s) includes previous studies showing that the levels of mRNA for plant nitrogen assimilatory genes such as glutamine synthetase ( <jats:italic>GLN</jats:italic> ) and asparagine synthetase ( <jats:italic>ASN</jats:italic> ) are modulated by carbon and organic nitrogen metabolites. Here, we have characterized a PII homolog ( <jats:italic>GLB1</jats:italic> ) in two higher plants, <jats:italic>Arabidopsis thaliana</jats:italic> and <jats:italic>Ricinus communis</jats:italic> (Castor bean). Each plant PII-like protein has high overall identity to <jats:italic>E. coli</jats:italic> PII (50%). Western blot analyses reveal that the plant PII-like protein is a nuclear-encoded chloroplast protein. The PII-like protein of plants appears to be regulated at the transcriptional level in that levels of <jats:italic>GLB1</jats:italic> mRNA are affected by light and metabolites. To initiate studies of the <jats:italic>in vivo</jats:italic> function of the <jats:italic>Arabidopsis</jats:italic> PII-like protein, we have constructed transgenic lines in which PII expression is uncoupled from its native regulation. Analyses of these transgenic plants support the notion that the plant PII-like protein may serve as part of a complex signal transduction network involved in perceiving the status of carbon and organic nitrogen. Thus, the PII protein found in archaea, bacteria, and now in higher eukaryotes (plants) is one of the most widespread regulatory proteins known, providing evidence for an ancestral metabolic regulatory mechanism that may have existed before the divergence of these three domains of life. </jats:p>

Journal

Citations (13)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top