CHANNELING OF DEOXYRIBOSE MOIETY OF EXOGENOUS DNA INTO CARBOHYDRATE-METABOLISM - ROLE OF DEOXYRIBOALDOLASE

In bacteria, the addition of (deoxy)nucleosides or (deoxy)ribose to th e growth medium causes induction of enzymes involved in their cataboli sm, leading to the utilisation of the pentose moiety as carbon and ene rgy source. In this respect, deoxyriboaldolase appears the key enzyme, allowing the utilisation of deoxyribose 5-P through glycolysis. We ob served that not only deoxynucleosides, but also PNA added to the growt h medium of Bacillus cereus induced deoxyriboaldolase; furthermore, th e switch of the culture from aerobic to anaerobic conditions caused a further increase in enzyme activity, leading to a more efficient chann elling of deoxyribose 5-P into glycolysis, probably as a response to t he low energy yield of the sugar fermentation. In eukaryotes, the cata bolism of (deoxy)nucleosides is well known. However, the research in t his field has been mainly devoted to the salvage of the bases formed b y the action of nucleoside phosphorylases, whereas the metabolic fate of the sugar moiety has been largely neglected. Our results indicate t hat the deoxyriboaldolase activity is present in the liver of several vertebrates and in a number of cell lines. We discuss our observations looking at the nucleic acids not only as informational molecules, but also as a not negligible source of readily usable phosphorylated suga r. (C) 1997 Elsevier Science Inc.