Fancy meeting you here! A fresh look at ''prokaryotic'' protein phosphorylation

Bacteria play host to a wide range of protein phosphorylation- dephosphorylation systems (Fig. 1). As little as five years ago the known systems were thought to be late-emerging and absolutely prokaryote specific. Today we know that most protein kinases and protein phosphatases are descended from a set of common, and possibly quite ancient, prototypes. Prokaryote- and eukaryote-specific protein kinases and protein phosphatases are rare find represent exceptions, not the rule as previously thought. Commonality suggests that a dynamic and versatile regulatory mechanism was first adapted to the modulation of protein function as early if not earlier than more 'basic' mechanisms, such as allosterism, etc. The existence of common molecular themes confirms that the microbial world offers a unique, largely untapped library and a powerful set of tools for the understanding of a regulatory mechanism which is crucial to all organisms, tools whose diversity and experimental malleability will provide new avenues for exploring and understanding key modes of cellular regulation.