The PII protein in the cyanobacterium Synechococcus sp. strain PCC 7942 is modified by serine phosphorylation and signals the cellular N-status.
The glnB gene product (PII protein) from Synechococcus sp. has previously been identified among 32P-labeled proteins, and its modification state has been observed to depend on both the nitrogen source and the spectral light quality (N. F. Tsinoremas, A. M. Castets, M. A. Harrison, J. F. Allen, and N. Tandeau de Marsac, Proc. Natl. Acad. Sci. USA 88:4565-4569, 1991). As shown in this study, modification of the PII protein primarily responds to the N-status of the cell, and its light-dependent variations are are mediated through nitrate metabolism. Modification of the PII protein results in the appearance of three isomeric forms with increasing negative charge. Unlike its homolog counterparts characterized so far, PII in Synechococcus sp. is modified by phosphorylation on a serine residue, which represents a unique kind of protein modification in bacterial nitrogen signalling pathways.
Forchhammer
K
K
Département de Biochimie et Génétique Moléculaire, Institut Pasteur, Paris, France.
Tandeau de Marsac
N
N
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D000458:Cyanobacteria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D008027:Light; D008969:Molecular Sequence Data; D051922:PII Nitrogen Regulatory Proteins; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D000644:Quaternary Ammonium Compounds / Q000378:metabolism* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction
D001426:Bacterial Proteins; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds; D011994:Recombinant Proteins; D010768:Phosphoserine; D012694:Serine; C404143:PIID regulatory protein, Bacteria