Biochemistry and regulatory functions of bacterial glucose kinases

• Glucokinases phosphorylate glucose from group donors such as ATP, ADP and polyP.
• Bacterial and eukaryotic hexokinase families use ATP or polyP as phosphoryl donors.
• ROK sugar kinases constitute the largest family of bacterial Glks with 3600 members.
• ATP-Glks seem to have also a regulatory function in carbon catabolite repression.
• Gly66, Asn104, Asp105, Glu154, His157 and Glu176 bind glucose in E. coli ATP-Glk.

Glucokinases (Glks) are enzymes widely distributed in all three domains of life. They are located at the beginning of the glycolytic pathway and are responsible for the glucose phosphorylation from various phosphate group donors such as ATP, ADP and polyphosphate. So far, there are eight crystallized Glks, and at least one belongs to each of the three reported Glk families. Structural studies have elucidated the mechanism for Glk action and multimerization. Cloning, overexpression and biochemical characterization have demonstrated the wide diversity of these enzymes. As reported for various microorganisms, in addition to their catalytic activity, some Glks, possessing ROK (Repressor Orf Kinases) motifs, also display a regulatory role. This function has been associated to the mechanisms of carbon catabolite regulation, morphological differentiation and antibiotic production. The present review covers the classification, detailed tertiary structure, mechanism of action, biochemical characterization and some regulatory aspects of bacterial Glks.

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