Summary: a mutants of have a constitutive aspartase activity and grow well on as partate as sole carbon source. mutants, which are deficient in high affinity aspartate transport as a result of the mutation, grow as well as mutants in medium containing high concentrations of aspartate and Na. This Naeffect is not due to an enhancement of aspartate transport but is the result of increased cellular metabolism. The ability to grow rapidly in sodium aspartate is induced by prior growth in the presence of Na. In potassium aspartate, the addition of arginine, citrulline, ornithine, Δ-pyrroline-5-carboxylate or proline instead of Naalso allows rapid growth; but in a mutant deficient in ornithine-oxo-acid aminotransferase, only pyrroline-carboxylate or proline can replace Na. The amino acid pool of cells growing slowly in potassium aspartate contains proline at a low concentration which increases upon addition of proline (but not Na) to the medium. Thus, Naaddition does not increase the synthesis of proline, but proline or pyrroline-carboxylate acts similarly to Naeither in preventing some inhibitory effect (by aspartate or the accumulating NH+) or in overcoming some deficiency (e.g. in further proline metabolism).


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error