Galactokinases: Potential Biotechnological Applications as Biocatalysts

Helena Kristiansson, David Timson

    Research output: Contribution to journalArticlepeer-review


    Galactokinase, a member of the GHMP (galactokinase, homoserine kinase, mevalonate kinase, phosphomevalonate kinase) family of kinases, catalyses the ATP-dependent phosphorylation of galactose at position 1 on the sugar. This reaction is important in the Leloir pathway of galactose catabolism. The need to produce monosaccharides phosphorylated at position 1 for the synthesis of complex molecules, including aminoglycoside antibiotics, has stimulated interest in exploiting the catalytic potential of galactokinases. However, the enzyme is quite specific, generally only catalysing the phosphorylation of D-galactose and closely related molecules. Directed evolution strategies have identified a key tyrosine residue (Tyr-371 in the Escherichia coli enzyme) which, although distant from the active site, influences the specificity of the enzyme. Alteration of this residue to histidine in E. coli and Lactococcus lactis galactokinases dramatically expanded the substrate range to include both D- and L-sugars. Similar experiments with the human enzyme demonstrated that alteration of the equivalent tyrosine (Tyr-379) to cysteine, lysine, arginine, serine or tryptophan increased the catalytic promiscuity of the enzyme. It has been hypothesised that these specificity changes arise because of alterations in the flexibility of the polypeptide chain. This hypothesis has yet to be tested experimentally. The biotechnological potential of galactokinases is clearly considerable and exploitation of closely related enzymes such as Nacetylgalactosamine kinase and arabinose kinase would expand that potential still further.
    Original languageEnglish
    Pages (from-to)148-154
    Number of pages7
    JournalCurrent Biotechnology
    Issue number2
    Publication statusPublished - 2012


    Dive into the research topics of 'Galactokinases: Potential Biotechnological Applications as Biocatalysts'. Together they form a unique fingerprint.

    Cite this