Protein Phosphorylation in Bacteria

Abstract

Protein kinases and phosphatases reversibly modify a widely, perhaps globally, distributed series of proteins that partake in signaling at the cellular level. The protein kinases responsible for these phosphorylations fall into several major families that are based on the specific amino acid residues that they modify. The most common types of protein phosphorylation, namely on the side chains of serine-threonine, tyrosine, histidine, and aspartate residues, are found in organisms from all three kingdoms of life. The phosphatases that catalyze the reverse, or dephosphorylation, reactions are also highly selective enzymes. Protein phosphorylationwasfirstidentifiedinEukarya,whereserinethreonine and tyrosine residues proved to be the common targets for kinases to add phosphate groups. These kinases and the proteins