Cation-Promoted Association of a Regulatory and Target Protein is Controlled by Protein Phosphorylation

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 91; no. 9; pp. 3544 - 3548
• Main Authors: Feese, Michael, Pettigrew, Donald W., Meadow, Norman D., Roseman, Saul, Remington, S. James
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 26-04-1994; National Acad Sciences; National Academy of Sciences
• Subjects: Atoms; Bacteria; Binding Sites; Biological and medical sciences; Biophysics; Cations, Divalent; Cellular biology; Computer Graphics; Crystal structure; Crystals; Electron density; Enzymes; Escherichia coli; Fundamental and applied biological sciences. Psychology; Glycerol Kinase - antagonists & inhibitors; Glycerol Kinase - metabolism; Interactions. Associations; Intermolecular phenomena; Ligands; Macromolecular Substances; Models, Molecular; Molecular biophysics; Phosphoproteins - metabolism; Phosphorylation; Protein Conformation; Proteins; Structure-Activity Relationship; Zinc; Zinc - metabolism; Phosphorylation; Regulation(control); Enzyme; Glycerol kinase; Transferases; Molecular interaction; Phosphoenolpyruvate-protein phosphotransferase; Property structure relationship; Binding site; Regulatory subunit; Zinc
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.91.9.3544

A central question in molecular biology concerns the means by which a regulatory protein recognizes different targets. IIIGlc, the glucose-specific phosphocarrier protein of the bacterial phosphotransferase system, is also the central regulatory element of the PTS. Binding of unphosphorylated IIIGlcinhibits several non-PTS proteins, but there is little or no sequence similarity between IIIGlcbinding sites on different target proteins. The crystal structure of Escherichia coli IIIGlcbound to one of its regulatory targets, glycerol kinase, has been refined at 2.6-⚬A resolution in the presence of products, adenosine diphosphate and glycerol 3-phosphate. Structural and kinetic analyses show that the complex of IIIGlcwith glycerol kinase creates an intermolecular Zn(II) binding site with ligation identical to that of the zinc peptidase thermolysin. The zinc is coordinated by the two active-site histidines of IIIGlc, a glutamate of glycerol kinase, and a water molecule. Zn(II) at 0.01 and 0.1 mM decreases the Kiof IIIGlcfor glycerol kinase by factors of about 15 and 60, respectively. The phosphorylation of one of the histidines of IIIGlc, in its alternative role as phosphocarrier, provides an elegant means of controlling the cation-enhanced protein-protein regulatory interaction. The need for the target protein to supply only one metal ligand may account for the lack of sequence similarity among the regulatory targets of IIIGlc.