Gln49 and Ser174 residues play critical roles in determining the catalytic efficiencies of plant glutamine synthetase

Keiki Ishiyama, Eri Inoue, Tomoyuki Yamaya, Hideki Takahashi

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Two essential residues playing critical roles in determining the substrate specificities of cytosolic glutamine synthetase (GS1) have been identified from the alignment of high-affinity (GLN1;1 and GLN1;4) and low-affinity (GLN1;2 and GLN1;3) GS1 isoenzymes in Arabidopsis, and confirmed by site-directed mutagenesis. The results indicated that either K49Q or A174S mutation is sufficient to increase the catalytic efficiencies of GLN1;3 by decreasing its Km values for ammonium. In contrast, replacement of Gln49 and Ser174 by lysine and alanine, respectively, was detrimental to glutamine synthetic activities in GLN1;4. The results suggested that Gln49 and Ser174 in the high-affinity GS1 isoenzymes are interchangeable with Lys49 and Ala174 in the low-affinity variants at the corresponding positions. JSPP

Original languageEnglish
Pages (from-to)299-303
Number of pages5
JournalPlant and Cell Physiology
Volume47
Issue number2
DOIs
Publication statusPublished - 2006 Feb

Keywords

  • Ammonium assimilation
  • Arabidopsis thaliana
  • Catalytic efficiency
  • Glutamine synthetase
  • Nitrogen metabolism
  • Site-directed mutagenesis

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

Fingerprint Dive into the research topics of 'Gln49 and Ser174 residues play critical roles in determining the catalytic efficiencies of plant glutamine synthetase'. Together they form a unique fingerprint.

Cite this