Publications

• Dimerization of bacterial diaminopimelate epimerase is essential for catalysis.

  Hor L., Dobson R.C., Downton M.T., Wagner J., Hutton C.A., Perugini M.A.

  Diaminopimelate (DAP) epimerase is involved in the biosynthesis of meso-DAP and lysine, which are important precursors for the synthesis of peptidoglycan, housekeeping proteins, and virulence factors in bacteria. Accordingly, DAP epimerase is a promising antimicrobial target. Previous studies repo ... >> More

  Diaminopimelate (DAP) epimerase is involved in the biosynthesis of meso-DAP and lysine, which are important precursors for the synthesis of peptidoglycan, housekeeping proteins, and virulence factors in bacteria. Accordingly, DAP epimerase is a promising antimicrobial target. Previous studies report that DAP epimerase exists as a monomeric enzyme. However, we show using analytical ultracentrifugation, X-ray crystallography, and enzyme kinetic analyses that DAP epimerase from Escherichia coli exists as a functional dimer in solution and the crystal state. Furthermore, the 2.0-Å X-ray crystal structure of the E. coli DAP epimerase dimer shows for the first time that the enzyme exists in an open, active conformation. The importance of dimerization was subsequently probed by using site-directed mutagenesis to generate a monomeric mutant (Y268A). Our studies show that Y268A is catalytically inactive, thus demonstrating that dimerization of DAP epimerase is essential for catalysis. Molecular dynamics simulations indicate that the DAP epimerase monomer is inherently more flexible than the dimer, suggesting that dimerization optimizes protein dynamics to support function. Our findings offer insight into the development of novel antimicrobial agents targeting the dimeric antibiotic target DAP epimerase. << Less

  J. Biol. Chem. 288:9238-9248(2013) [PubMed] [EuropePMC]

• Structural basis for redox sensitivity in Corynebacterium glutamicum diaminopimelate epimerase: an enzyme involved in l-lysine biosynthesis.

  Sagong H.Y., Kim K.J.

  Diaminopimelate epimerase (DapF) is one of the crucial enzymes involved in l-lysine biosynthesis, where it converts l,l-diaminopimelate (l,l-DAP) into d,l-DAP. DapF is also considered as an attractive target for the development of antibacterial drugs. Here, we report the crystal structure of DapF ... >> More

  Diaminopimelate epimerase (DapF) is one of the crucial enzymes involved in l-lysine biosynthesis, where it converts l,l-diaminopimelate (l,l-DAP) into d,l-DAP. DapF is also considered as an attractive target for the development of antibacterial drugs. Here, we report the crystal structure of DapF from Corynebacterium glutamicum (CgDapF). Structures of CgDapF obtained under both oxidized and reduced conditions reveal that the function of CgDapF is regulated by redox-switch modulation via reversible disulfide bond formation between two catalytic cysteine residues. Under oxidized condition, two catalytic cysteine residues form a disulfide bond; these same cysteine residues exist in reduced form under reduced condition. Disulfide bond formation also induces a subsequent structural change in the dynamic catalytic loop at the active site, which results in open/closed conformational change at the active site. We also determined the crystal structure of CgDapF in complex with its product d,l-DAP, and elucidated how the enzyme recognizes its substrate l,l-DAP as a substrate. Moreover, the structure in complex with the d,l-DAP product reveals that CgDapF undergoes a large open/closed domain movement upon substrate binding, resulting in a completely buried active site with the substrate bound. << Less

  Sci Rep 7:42318-42318(2017) [PubMed] [EuropePMC]

• The stereoisomers of alpha epsilon-diaminopimelic acid. III. Properties and distribution of diaminopimelic acid racemase, an enzyme causing interconversion of the LL and meso isomers.

  ANTIA M., HOARE D.S., WORK E.

  Biochem J 65:448-459(1957) [PubMed] [EuropePMC]

• Crystal structure of diaminopimelate epimerase from Arabidopsis thaliana, an amino acid racemase critical for L-lysine biosynthesis.

  Pillai B., Moorthie V.A., van Belkum M.J., Marcus S.L., Cherney M.M., Diaper C.M., Vederas J.C., James M.N.

  Diaminopimelate (DAP) epimerase is a key enzyme for the biosynthesis of lysine in plants. Lysine is an essential dietary nutrient for mammals. In both plants and bacteria, DAP epimerase catalyzes the interconversion of LL-DAP and DL(meso)-DAP. The absence of a mammalian homolog makes DAP epimerase ... >> More

  Diaminopimelate (DAP) epimerase is a key enzyme for the biosynthesis of lysine in plants. Lysine is an essential dietary nutrient for mammals. In both plants and bacteria, DAP epimerase catalyzes the interconversion of LL-DAP and DL(meso)-DAP. The absence of a mammalian homolog makes DAP epimerase a promising target for the design of novel herbicides and antibacterials. This enzyme requires no cofactors and it functions through an unusual mechanism involving two cysteine residues acting in concert and alternating as a base (thiolate) and as an acid (thiol). The present study reports the crystal structures of two enzyme-inhibitor complexes of DAP epimerase from Arabidopsis thaliana with different isomers of the irreversible inhibitor and substrate mimic, 2-(4-amino-4-carboxybutyl)-aziridine-2-carboxylate, at 1.95 and 2.3 A resolution. These structures provide the first atomic details of a plant amino acid racemase. Structural analysis reveals that ligand binding to a cleft between the two domains of the enzyme is accompanied by domain closure with two strictly conserved cysteine residues, Cys99 and Cys254, optimally positioned to perform acid/base catalysis via a carbanion stabilization mechanism on the stereogenic alpha-carbon atom of the amino acid. Stereochemical control in catalysis is achieved by means of a highly symmetric catalytic site that can accommodate both the L and D stereogenic centers of DAP at the proximal site, whereas specific interactions at the distal site require only the L configuration. Structural comparisons of the plant enzyme with its bacterial counterpart from Haemophilus influenzae reveal significant conservation of amino acid residues around the active site that extends to their three-dimensional structures and catalytic mechanism. << Less

  J. Mol. Biol. 385:580-594(2009) [PubMed] [EuropePMC]

• Dynamics of catalysis revealed from the crystal structures of mutants of diaminopimelate epimerase.

  Pillai B., Cherney M., Diaper C.M., Sutherland A., Blanchard J.S., Vederas J.C., James M.N.

  Diaminopimelate (DAP) epimerase catalyzes the stereoinversion of ll-DAP to meso-DAP, a precursor of l-lysine and an essential component of the bacterial peptidoglycan. This function is vital to bacteria and the enzyme therefore represents an attractive target for the design of novel anti-bacterial ... >> More

  Diaminopimelate (DAP) epimerase catalyzes the stereoinversion of ll-DAP to meso-DAP, a precursor of l-lysine and an essential component of the bacterial peptidoglycan. This function is vital to bacteria and the enzyme therefore represents an attractive target for the design of novel anti-bacterials. DAP epimerase belongs to the group of PLP-independent amino acid racemases that function through a rather unusual mechanism involving two cysteines acting in concert as a base (thiolate) and an acid (thiol). We have solved the crystal structures of the apo-forms of DAP epimerase mutants (C73S and C217S) from Haemophilus influenzae at 2.3A and 2.2A resolution, respectively. These structures provide a snapshot of the enzyme in the first step of the catalytic cycle. Comparisons with the structures of the inhibitor-bound form reveal that the enzyme adopts an 'open conformation' in the absence of substrates or inhibitors with the two active site cysteines existing as a thiol-thiolate pair. Substrate binding to the C-terminal domain triggers the closure of the N-terminal domain coupled with tight encapsulation of the ligand, stabilization of the conformation of an active site loop containing Cys73 and expulsion of water molecules with concomitant desolvation of the thiolate base. This structural rearrangement is critical for catalysis. << Less

  Biochem. Biophys. Res. Commun. 363:547-553(2007) [PubMed] [EuropePMC]