Characterization of genes involved in fructose utilization by Lactobacillus fermentum

Miia Helanto, Johannes Aarnikunnas, Airi Palva, Matti Leisola, Antti Nyyssölä

    Research output: Contribution to journalArticleScientificpeer-review


    The genes encoding phosphoglucose isomerase (fruI) and fructokinase (fruK) of Lactobacillus fermentum NRRL-B-1932 were sequenced. They constituted an operon, which is involved in fructose metabolism of this strain by channeling intracellular fructose into the phosphoketolase pathway. A third open reading frame, unkR, upstream of the operon was identified as homologous to genes of LacI/GalR family repressors. The UnkR repressor's role in transcriptional control of the fruIK operon could, however, not be established by electrophoretic mobility shift assay (EMSA) analysis. Sequence analysis revealed two putative catabolite responsive elements (cre) in the promoter region of fruIK suggesting that the fruIK operon is under negative regulatory control by carbon catabolite repression. Expression and enzyme activity data were compatible with the assumption that the fruIK operon is represessed by glucose. No sugar specific phosphoenolpyruvate sugar transferase system activity for the transport of fructose, glucose, sucrose or mannose could be detected in L. fermentum NRRL-B-1932 cells, which suggest that fructose is taken up by a permease system.
    Original languageEnglish
    JournalArchives of Microbiology
    Issue number1
    Pages (from-to)51-59
    Number of pages9
    Publication statusPublished - 2006
    MoE publication typeA1 Journal article-refereed

    Fields of Science

    • 413 Veterinary science
    • bakteerit
    • maitohappobakteerit
    • Lactobacillus fermentum
    • geenit
    • fruktoosi
    • aineenvaihdunta
    • mannitoli

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