These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Genetics of a novel starch utilisation pathway present in Klebsiella oxytoca.
    Author: Fiedler G, Pajatsch M, Böck A.
    Journal: J Mol Biol; 1996 Feb 23; 256(2):279-91. PubMed ID: 8594196.
    Abstract:
    A 14.3 kb DNA fragment from Klebsiella oxytoca M5a1 has been cloned and shown to provide Escherichia coli with the capacity for growth on alpha- and beta-cyclodextrins. This fragment is located immediately upstream of the previously identified cgt gene coding for cyclodextrin glycosyltransferase. It contains ten genes (cym) organised in two divergently oriented clusters separated by a non-coding region of 419 bp. Four of the genes code for products homologous to the maltose and linear maltodextrin uptake system, another one for a putative cytoplasmic cyclodextrinase. The cym genes of K. oxytoca are distinct and different from the mal genes; cym mutations do not affect maltose catabolism. On the other hand, whereas mutations in the maltose/maltodextrin-uptake genes do not influence cyclodextrin metabolism, a mutation inactivating the malPQ genes coding for maltodextrin phosphorylase and amylomaltase does. Cyclodextrin catabolism is independent of the presence of a functional cyclodextrin glycosyltransferase but degradation of starch and gamma-cyclodextrins requires the activity of this enzyme. The results indicate the existence of a novel starch degradation pathway which involves the extracellular conversion of starch into cyclodextrins by cyclodextrin glycosyltransferase, uptake of the cyclodextrins by a specific uptake system and intracellular linearisation by a cyclodextrinase. The malto-oligosaccharides produced are then channelled into the maltodextrin-degradation route involving the activity of maltodextrin phosphorylase and amylomaltase.
    [Abstract] [Full Text] [Related] [New Search]