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First published online December 16, 2005; 10.1104/pp.105.072629 Plant Physiology 140:292-301 (2006) © 2006 American Society of Plant Biologists An LL-Diaminopimelate Aminotransferase Defines a Novel Variant of the Lysine Biosynthesis Pathway in Plants1,[W]Biotech Center and Department of Plant Biology and Pathology, Rutgers University, New Brunswick, New Jersey 08901 (A.O.H., T.L.); Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544 (C.G.); and BASF Plant Science, Research Triangle Park, North Carolina 27709 (B.K.S.)
Although lysine (Lys) biosynthesis in plants is known to occur by way of a pathway that utilizes diaminopimelic acid (DAP) as a central intermediate, the available evidence suggests that none of the known DAP-pathway variants found in nature occur in plants. A new Lys biosynthesis pathway has been identified in Arabidopsis (Arabidopsis thaliana) that utilizes a novel transaminase that specifically catalyzes the interconversion of tetrahydrodipicolinate and LL-diaminopimelate, a reaction requiring three enzymes in the DAP-pathway variant found in Escherichia coli. The LL-DAP aminotransferase encoded by locus At4g33680 was able to complement the dapD and dapE mutants of E. coli. This result, in conjunction with the kinetic properties and substrate specificity of the enzyme, indicated that LL-DAP aminotransferase functions in the Lys biosynthetic direction under in vivo conditions. Orthologs of At4g33680 were identified in all the cyanobacterial species whose genomes have been sequenced. The Synechocystis sp. ortholog encoded by locus sll0480 showed the same functional properties as At4g33680. These results demonstrate that the Lys biosynthesis pathway in plants and cyanobacteria is distinct from the pathways that have so far been defined in microorganisms.
1 This work was funded by a grant from the National Science Foundation (IBN0449542 to T.L. and C.G.) and the National Institutes of Health Predoctoral Fellowship (GM069264 to A.O.H.) and Institutional Training Grant (GM55145). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Thomas Leustek (leustek{at}rutgers.edu). [W] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.072629. * Corresponding author; e-mail leustek{at}rutgers.edu; fax 7329320312. Received October 6, 2005; returned for revision November 2, 2005; accepted November 3, 2005. This article has been cited by other articles:
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