1p9l: Difference between revisions

[[Image:1p9l.gif|left|200px]]<br /><applet load="1p9l" size="350" color="white" frame="true" align="right" spinBox="true"  

Dihydrodipicolinate reductase (DHPR) catalyzes the reduced pyridine nucleotide-dependent reduction of the alpha,beta-unsaturated cyclic imine, dihydrodipicolinate, to generate tetrahydrodipicolinate. This enzyme catalyzes the second step in the bacterial biosynthetic pathway that generates meso-diaminopimelate, a component of bacterial cell walls, and the amino acid L-lysine. The Mycobacterium tuberculosis dapB-encoded DHPR has been cloned, expressed, purified, and crystallized in two ternary complexes with NADH or NADPH and the inhibitor 2,6-pyridinedicarboxylate (2,6-PDC). The structures have been solved using molecular replacement strategies, and the DHPR-NADH-2,6-PDC and DHPR-NADPH-2,6-PDC complexes have been refined against data to 2.3 and 2.5 A, respectively. The M. tuberculosis DHPR is a tetramer of identical subunits, with each subunit composed of two domains connected by two flexible hinge regions. The N-terminal domain binds pyridine nucleotide, while the C-terminal domain is involved in both tetramer formation and substrate/inhibitor binding. The M. tuberculosis DHPR uses NADH and NADPH with nearly equal efficiency based on V/K values. To probe the nature of this substrate specificity, we have generated two mutants, K9A and K11A, residues that are close to the 2'-phosphate of NADPH. These two mutants exhibit decreased specificity for NADPH by factors of 6- and 30-fold, respectively, but the K11A mutant exhibits 270% of WT activity using NADH. The highly conserved structure of the nucleotide fold may permit other enzyme's nucleotide specificity to be altered using similar mutagenic strategies.

1P9L is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis] with <scene name='pdbligand=NAD:'>NAD</scene>, <scene name='pdbligand=PDC:'>PDC</scene> and <scene name='pdbligand=PG4:'>PG4</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Dihydrodipicolinate_reductase Dihydrodipicolinate reductase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.3.1.26 1.3.1.26] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1P9L OCA].  

[[Category: Blanchard, J S.]]

[[Category: TBSGC, TB Structural Genomics Consortium.]]

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