The enzymes involved in the lysine biosynthetic pathway have long been considered to be attractive targets for novel antibiotics due to the absence of this pathway in humans. Recently, a novel pyridoxal 5'-phosphate (PLP) dependent enzyme called LL-diaminopimelate aminotransferase (LL-DAP-AT) was identified in the lysine biosynthetic pathway of plants and Chlamydiae. Understanding its function and substrate recognition mechanism would be an important initial step toward designing novel antibiotics targeting LL-DAP-AT. The crystal structures of LL-DAP-AT from Arabidopsis thaliana in complex with various substrates and analogues have been solved recently. These structures revealed how L-glutamate and LL-DAP are recognized by LL-DAP-AT without significant conformational changes in the enzyme's backbone structure. This review article summarizes the recent developments in the structural characterization and the inhibitor design of LL-DAP-AT from A. thaliana. This article is part of a Special Issue entitled: Pyridoxal Phospate Enzymology. (C) 2011 Elsevier B.V. All rights reserved.