An additional P II in Escherichia coli: a new regulatory protein in the glutamine synthetase cascade

Abstract

The P II protein in the glutamine synthetase cascade transduces the nitrogen signal, as sensed by uridylyltransferase, both to the NRII/NRI two-component system and to adenylyltransferase, to regulate the activity of glutamine synthetase. Here we describe the amplification of a chromosomal DNA fragment from Escherichia coli which contains the sequence of a P II homologue. The derived amino acid sequence of this DNA fragment is 67% identical to E. coli P II. It contains the conserved tyrosine residue which is known to be the site of uridylylation in P II. E. coli is the first organism in which two different P II proteins have been detected.