ISSN:
1573-4927
Keywords:
l-glutamate transport
;
l-glutamate utilization
;
aspartase
;
Salmonella typhimurium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Two systems for l-glutamate transport were found in Salmonella typhimurium LT-2 GltU+ (glutamate utilization) mutants. The first one is similar to the glt system previously described in Escherichia coli; by transductional analysis the structural gene, gltS, coding for the transport protein was located at minute 80 of the chromosome as part of the operon gltC-gltS, and its regulator, the gltR gene, near minute 90; the gltS gene product transports both l-glutamate and l-aspartate, is sodium independent, and is β-hydroxyaspartate sensitive. The second transport system, whose structural gene was called gltF and is located at minute 0, was l-glutamate specific, sodium independent, and α-methylglutamate sensitive. Two aspartase activities occurred in S. typhimurium LT-2: the first one was present only in the GltU+ mutants, had a pH 6.4 optimum, was essential for both l-glutamate and l-aspartate metabolism, and mapped at minute 94, close to the ampC gene. The second one had a pH 7.2 optimum, could be induced by several amino acids, and thus may have a general role in nitrogen metabolism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00502788
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