Previous Article | Next Article ![]()
Appl Environ Microbiol, May 1998, p. 1805-1811, Vol. 64, No. 5
Department of Pediatrics, University of
Minnesota, Minneapolis, Minnesota 55455,1 and
Department of Molecular Biology and Microbiology, Tufts
University School of Medicine, Boston, Massachusetts
021112
Received 8 December 1997/Accepted 6 March 1998
The goal of this work was to construct Escherichia coli
strains capable of enhanced arginine production. The arginine
biosynthetic capacity of previously engineered E. coli
strains with a derepressed arginine regulon was limited by the
availability of endogenous ornithine (M. Tuchman, B. S. Rajagopal,
M. T. McCann, and M. H. Malamy, Appl. Environ. Microbiol.
63:33-38, 1997). Ornithine biosynthesis is limited due to feedback
inhibition by arginine of N-acetylglutamate synthetase
(NAGS), the product of the argA gene and the first enzyme
in the pathway of arginine biosynthesis in E. coli. To circumvent this inhibition, the argA genes from E. coli mutants with feedback-resistant (fbr) NAGS were cloned into
plasmids that contain "arg boxes," which titrate the
ArgR repressor protein, with or without the E. coli carAB
genes encoding carbamyl phosphate synthetase and the argI
gene for ornithine transcarbamylase. The free arginine production rates
of "arg-derepressed" E. coli cells overexpressing plasmid-encoded carAB, argI, and
fbr argA genes were 3- to 15-fold higher than that of an
equivalent system overexpressing feedback-sensitive wild-type (wt)
argA. The expression system with fbr argA
produced 7- to 35-fold more arginine than a system overexpressing
carAB and argI genes on a plasmid in a strain
with a wt argA gene on the chromosome. The arginine
biosynthetic capacity of arg-derepressed DH5
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Use of Inducible Feedback-Resistant
N-Acetylglutamate Synthetase (argA) Genes for
Enhanced Arginine Biosynthesis by Genetically Engineered
Escherichia coli K-12 Strains
strains
with plasmids containing only the fbr argA gene was similar
to that of cells with plasmids also containing the carAB
and argI genes. Plasmids containing wt or fbr
argA were stably maintained under normal growth conditions for at least 18 generations. DNA sequencing identified different point
mutations in each of the fbr argA mutants, specifically H15Y, Y19C, S54N, R58H, G287S, and Q432R.
*
Corresponding author. Mailing address: Department of
Molecular Biology and Microbiology, Tufts University School of
Medicine, 136 Harrison Ave., Boston, Massachusetts 02111. Phone: (617)
636-6756. Fax: (617) 636-0337. E-mail:
mmalamy1{at}opal.tufts.edu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»