title: Phosphoprotein PII from cyanobacteria--analysis of functional conservation with the PII signal-transduction protein from Escherichia coli.
abstract: The signal transduction protein PII from Escherichia coli is modified by uridylylation, whereas its counterpart from the cyanobacterium Synechococcus PCC 7942 is phosphorylated at a seryl residue. To elucidate functional conservations between these proteins, we compared the Synechococcus PII protein with the known properties of the E. coli PII protein. Similar to the E. coli protein, Synechococcus PII binds the metabolites 2-oxoglutarate and ATP in a mutually dependent manner. The synergism of ligand binding was analyzed in detail. The ATP-binding site of Synechococcus PII could be labelled with 5'-p-fluorosulfonylbenzoyladenosine. By heterologous expression of the cyanobacterial glnB gene in E. coli we showed that Synechococcus PII can be modified by the E. coli PII uridylyltransferase. The presence of Synechococcus PII prevents signal transduction of E. coli PII to NtrB, presumably by non-functional competition. We therefore propose that the primary function of Synechococcus PII is to sense 2-oxoglutarate, the carbon skeleton required for nitrogen assimilation.
authors.affiliation: Lehrstuhl für Mikrobiologie der Universität München, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Forchhammer
authors.forename: A
authors.initials: A
authors.lastname: Hedler
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D015345:Oligonucleotide Probes / Q000235:genetics; D051922:PII Nitrogen Regulatory Proteins; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D015345:Oligonucleotide Probes; D051922:PII Nitrogen Regulatory Proteins; D011994:Recombinant Proteins; C404143:PIID regulatory protein, Bacteria