Premium
The Synechococcus elongatus P II signal transduction protein controls arginine synthesis by complex formation with N ‐acetyl‐ l ‐glutamate kinase
Author(s) -
Heinrich Annette,
Maheswaran Mani,
Ruppert Ulrike,
Forchhammer Karl
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2004.04058.x
Subject(s) - biology , phosphorylation , phosphoprotein , signal transduction , biochemistry , kinase , arginine , enzyme , microbiology and biotechnology , amino acid
Summary This communication identifies, for the first time, a receptor protein for signal perception from the P II signal transduction protein in the cyanobacterium Synechococcus elongatus . P II , a phosphoprotein that signals the carbon/nitrogen status of the cells, forms a tight complex with the key enzyme of the arginine biosynthetic pathway, N ‐acetylglutamate (NAG) kinase. In complex with P II , the catalytic activity of NAG kinase is strongly enhanced. Complex formation does not require the effector molecules of P II , 2‐oxoglutarate and ATP, but it is highly susceptible to modifications at the phosphorylation site of P II , Ser‐49. Stable complexes were only formed with the non‐phosphorylated form of P II but not with Ser‐49 mutants. In accordance with these data, NAG kinase activity in S. elongatus extracts correlated with the phosphorylation state of P II , with high NAG kinase activities corresponding to non‐phosphorylated P II (nitrogen‐excess conditions) and low activities to increased levels of P II phosphorylation (nitrogen‐poor conditions), thus subjecting the key enzyme of arginine biosynthesis to global nitrogen control.