Regulation of nitrate reductase by non-modifiable derivatives of PII in the cells of Synechococcus elongatus strain PCC 7942.
In Synechococcus elongatus, the PII protein inhibits both transport and reduction of nitrate when ammonium is present in the medium. Using a transporter mutant having ammonium-resistant nitrate transport activity as the genetic background, we analyzed specific effects of PII on in vivo nitrate reductase activity by measuring uptake of nitrate from the medium. The results showed that the regulation of nitrate reductase does not require changes in the electric charge or size of the side chain at the phosphorylation site of PII. Phosphorylation of PII is thus unlikely to play a role in the regulation of nitrate reductase.
Takatani
Nobuyuki
N
Laboratory of Molecular Plant Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan.
Kobayashi
Masaki
M
Maeda
Shin-Ichi
S
Omata
Tatsuo
T
D015964:Gene Expression Regulation, Bacterial; D050901:Nitrate Reductase / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D051922:PII Nitrogen Regulatory Proteins / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D046940:Synechococcus / Q000201:enzymology*
D009566:Nitrates; D051922:PII Nitrogen Regulatory Proteins; D050901:Nitrate Reductase; C006568:ammonium nitrate