Purine nucleosides and Cytidine uptake in Lactococcus lactis share a common transporter of the ABC type
Special Symposium - Innovations in Food Technology (LMC Congress)
Innovations in Food Technology - Poster Session (Food - P2)
Keywords: nucleotide metabolism, transporters, bacterial physiology
In order to optimize the performance of the cheese starter Lactococcus lactis, knowledge of the central biochemical pathways is of crucial importance. Some of the most important biochemical pathways are those involved in nucleotide metabolism, since any growing organism needs nucleotides for the synthesis of DNA, RNA and several co-enzymes. Moreover, nucleotides are acting as allosteric effectors for a large number of enzymatic reactions. Therefore, alteration of nucleotide pool sizes may have significant effects on a large number of biochemical pathways, leading to changes in cell physiology. In this work, the presence of two different high affinity nucleoside transporters is demonstrated: One system is responsible for uridine uptake and another system is responsible for the uptake of all purine nucleosides and cytidine. Transposon induced mutations in the purine/cytidine transporter have been obtained, and the affected genes identified. The transporter was shown to be of the ABC type.
The unusual properties of nucleoside transport are used to establish physiological conditions where nucleotide pools are altered by addition of nucleosides in different combinations. Inhibition of inosine uptake in a purine requiring strain by cytidine lead to reduction of internal purine nucleotide pools and a decreased growth rate. A similar effect is seen for inhibition of cytidine uptake in a pyrimidine requiring strain by purine nucleosides, except that pyrimidine pools were lowered.
Presented Thursday 20, 13:30 to 14:40, in session Innovations in Food Technology - Poster Session (Food - P2).
