TY - JOUR
T1 - Gln49 and Ser174 residues play critical roles in determining the catalytic efficiencies of plant glutamine synthetase
AU - Ishiyama, Keiki
AU - Inoue, Eri
AU - Yamaya, Tomoyuki
AU - Takahashi, Hideki
N1 - Funding Information:
RIKEN Plant Science Center is supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan. This work was supported in part by the following grants to T.Y.: Grant-in-aid for Scientific Research on Priority Area (grant No. 16085201) from the Ministry of Education, Culture, Sports, Science and Technology of Japan; Core Research for the Evolutional Science and Technology (CREST) of Japan Science and Technology; and The Project for Rice Genome Research (grant No. IP1016) from the Ministry of Agriculture, Forestry and Fisheries of Japan.
PY - 2006/2
Y1 - 2006/2
N2 - 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
AB - 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
KW - Ammonium assimilation
KW - Arabidopsis thaliana
KW - Catalytic efficiency
KW - Glutamine synthetase
KW - Nitrogen metabolism
KW - Site-directed mutagenesis
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U2 - 10.1093/pcp/pci238
DO - 10.1093/pcp/pci238
M3 - Article
C2 - 16338958
AN - SCOPUS:33644902976
SN - 0032-0781
VL - 47
SP - 299
EP - 303
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
IS - 2
ER -