Physiological basis for preferential uptake of D-alpha-aminoadipate over the L-isomer by Alcaligenes denitrificans.
Alcaligenes denitrificans, pre-incubated with D-alpha-aminoadipate and assayed for L-isomer uptake without removal of extracellular D-isomer, exhibits a reduced rate of uptake and a reduced level at which steady state is achieved. During D- or L-isomer uptake, intracellular alpha-aminoadipate is exclusively the L-configuration. These data are consistent with an intracellular, mediated reduction in L-isomer uptake as the physiological basis for preferential D-alpha-aminoadipate uptake by A. denitrificans growing on racemic alpha-aminoadipate. Translocated D-alpha-aminoadipate is rapidly metabolized to form an L-isomer pool which subsequently reduces the rate of L-isomer uptake and the level at which steady state occurs resulting in a preferred D-isomer uptake. Competitive inhibition of L-alpha-aminoadipate uptake by the D-isomer or a difference in the maximum rates of uptate uptake is an inducible process expressed only in the presence of that compound and while uptake of L-alpha-animoadipate is also inducible there is a low rate of constitutive uptake. While L-alpha-aminoadipate uptake occurs against a concentration gradient, uptake of the D-isomer is not against a gradient. D- and L-isomer uptake are active processes since both are inhibited by azide, cyanide and 2,4-dinitrophenol.
D000272:Adipates / Q000378:metabolism* / Q000494:pharmacology; D000421:Alcaligenes / Q000378:metabolism*; D000600:Amino Acids, Dicarboxylic / Q000378:metabolism* / Q000494:pharmacology; D001681:Biological Assay; D001692:Biological Transport; D007700:Kinetics; D011549:Pseudomonas / Q000187:drug effects; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013997:Time Factors
D000272:Adipates; D000600:Amino Acids, Dicarboxylic