Estimation of compartmentation of lysine inside the cells of Yarrowia lipolytica.

We studied the compartmentation of lysine in vivo by the tracer method of Subramanian et al. (J. Bacteriol. 115 (1973) 284-290). To calculate the size of the different lysine pools and lysine fluxes inside the cell, a mathematical model was designed enabling quantitative estimation of these data from experimental measurements. This technique was applied to a lysine-accumulating strain, 15901.7, and to its low lysine pool derivatives, ply-1, ply-4 and ply-9, which were selected for their low polyphosphate pools. In the mother strain, 15901.7, it appeared that lysine was stored mainly in a non-cytoplasmic compartment. In the mutants, the efflux from this compartment was higher and accounted for the higher percentage of lysine in the cytoplasm of these strains. Simulation with calculated parameters fitted the experimental curves very well. This was good evidence for the pertinence of the model. The biological significance of these results are discussed.