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Applied and Environmental Microbiology, September 2008, p. 5497-5503, Vol. 74, No. 17
0099-2240/08/$08.00+0     doi:10.1128/AEM.00262-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Corynebacterium glutamicum Contains 3-Deoxy-D-Arabino-Heptulosonate 7-Phosphate Synthases That Display Novel Biochemical Features ^,

Ya-Jun Liu,^1, Pan-Pan Li,^1, Ke-Xin Zhao,¹ Bao-Jun Wang,¹ Cheng-Ying Jiang,¹ Harold L. Drake,² and Shuang-Jiang Liu^1*

State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China,¹ Department of Ecological Microbiology, University of Bayreuth, 95440 Bayreuth, Germany²

Received 30 January 2008/ Accepted 6 July 2008

3-Deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (EC 2.5.1.54) catalyzes the first step of the shikimate pathway that finally leads to the biosynthesis of aromatic amino acids phenylalanine (Phe), tryptophan (Trp), and tyrosine (Tyr). In Corynebacterium glutamicum ATCC 13032, two chromosomal genes, NCgl0950 (aroF) and NCgl2098 (aroG), were located that encode two putative DAHP synthases. The deletion of NCgl2098 resulted in the loss of the ability of C. glutamicum RES167 (a restriction-deficient strain derived from C. glutamicum ATCC 13032) to grow in mineral medium; however, the deletion of NCgl0950 did not result in any observable phenotypic alteration. Analysis of DAHP synthase activities in the wild type and mutants of C. glutamicum RES167 indicated that NCgl2098, rather than NCgl0950, was involved in the biosynthesis of aromatic amino acids. Cloning and expression in Escherichia coli showed that both NCgl0950 and NCgl2098 encoded active DAHP synthases. Both the NCgl0950 and NCgl2098 DAHP synthases were purified from recombinant E. coli cells and characterized. The NCgl0950 DAHP synthase was sensitive to feedback inhibition by Tyr and, to a much lesser extent, by Phe and Trp. The NCgl2098 DAHP synthase was slightly sensitive to feedback inhibition by Trp, but not sensitive to Tyr and Phe, findings that were in contrast to the properties of previously known DAHP synthases from C. glutamicum subsp. flavum. Both Co²⁺ and Mn²⁺ significantly stimulated the NCgl0950 DAHP synthase's activity, whereas Mn²⁺ was much more stimulatory than Co²⁺ to the NCgl2098 DAHP synthase's activity.

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* Corresponding author. Mailing address: Institute of Microbiology, Chinese Academy of Sciences, Datun Road Jia-3#, Chaoyang District, Beijing 100101, People's Republic of China. Phone: 86-10-64807421. Fax: 86-10-64807423. E-mail: liusj{at}sun.im.ac.cn

Supplemental material for this article may be found at http://aem.asm.org/.

Published ahead of print on 11 July 2008.

These two authors contributed equally to this work.

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Applied and Environmental Microbiology, September 2008, p. 5497-5503, Vol. 74, No. 17
0099-2240/08/$08.00+0     doi:10.1128/AEM.00262-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

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