L-Aspartate -decarboxylase (ADC) belongs to a class of pyruvoyl dependent enzymes and catalyzes the conversion of aspartate to -alanine in the pantothenate pathway, which is critical for the growth of several micro-organisms, including (Mtb). a lyase and catalyzes the decarboxylation of aspartate to -alanine, which is essential for D-pantothenate formation (Fig. S1). Mutants of the gene are defective in -alanine biosynthesis . -alanine and D-pantoate condense to form pantothenate, a precursor of coenzyme A (CoA), which functions as an acyl carrier in fatty acid metabolism and provides the 4-phosphopantetheine prosthetic group in fatty acid biosynthesis, an essential need for the growth of several micro-organisms, including (Mtb) , , the causative bacterial agent of tuberculosis (Tb) . The unique lipid rich cell wall of Mtb is responsible for the unusually low permeability, virulence and resistance to therapeutic brokers , buy AZD2014 . At the heart of the fight against tuberculosis lies its cell wall, a multilayered structure adorned with a number of lipo-glycans that protect the bacterium in antimicrobial defense against environmental stresses and buy AZD2014 treatment. Consequently, the Rabbit polyclonal to PGM1 metabolism and biosynthesis of lipids buy AZD2014 and lipo-glycans play a pivotal role in the intracellular survival and persistence of Mtb. Any impediment in the pantothenate pathway will therefore affect the survival of the bacterium. As Mtb is usually notorious to develop resistance towards drugs, progress in the treatment of tuberculosis will require us to identify new targets in pathways critical for the sustenance of Mtb, and to develop new drugs selectively inhibiting these targets so as to minimize drug resistance and potential side effects , . Since pantothenate is usually synthesized only in microorganisms, fungi and plants, but not in humans, the enzymes that are involved in this biosynthetic pathway qualify to be potential targets for antibacterial and antifungal brokers . The absence of this pathway in humans ensures that any inhibitor or drug against ADC would have low toxicity in patients. In particular, the chance of side effects in a long term treatment buy AZD2014 process will be minimal. Moreover, the presence of the ADC gene in only one copy in the Mtb buy AZD2014 genome further enhances its importance as a suitable drug target. MtbADC is usually translated as an unprocessed proenzyme (-protein). It undergoes autocatalyzed cleavage between Gly24 and Ser25, where the serine is usually altered to a pyruvoyl group, resulting in the formation of 2.8 kDa -chain and 11 kDa -chain made up of the N-terminal pyruvoyl group. This processed form is necessary for the conversion of aspartate to -alanine  and the mutation S25A makes the protein uncleavable and inactive . So far, crystal structures have been decided for unprocessed (uncleaved) ADC from (PDB id: 1PPY) , Mtb (2C45) , and processed ADC from (1AW8) , (3OUG), (3PLX), ADC (TthADC) (1VC3), TthADC, complexed with substrate analog fumarate (2EEO), ADC (HpyADC) (1UHD)  and HpyADC, complexed with substrate analog isoasparagine (1UHE) . The ADC protein folds into a double- -barrel structure. It forms a homotetramer  and the active site is usually shown to be at the interface of a dimer of processed ADC . The unique feature of being absent in human, in addition to its significance in the cellular metabolism of Mtb, endows unique significance upon ADC as an important drug and vaccine target. Jacobs and coworkers  constructed a double deletion mutant (mutant were able to survive 22 weeks longer than those infected with the bacille Calmette-Guerin-Pasteur (BCG-P) strain. Deletion of the genes significantly attenuates Mtb and protects infected animals against tuberculosis. In an effort to discover inhibitors against ADC, -hydroxyaspartate, L-cysteic acid, D-serine, oxaloacetate and succinic dehydrazine are reported as competitive inhibitors of ADC with Ki of 0.13, 0.08, 0.16, 0.81, 0.73 mM, respectively , ,  and phenylhydrazine binds to the pyruvoyl group to inactivate the protein . While D-serine, -hydroxyaspartate, and L-cysteic acid interfere with the synthesis of pantothenic acid in bacteria, external supply of aspartic acid, -alanine, or pantothenic acid can reverse their growth inhibitory action in ADC structures  by the use of Multiprot  shows a root mean square deviation (RMSD) of 0.19 ? for 89 C atom pairs. This suggests that the unprocessed and processed ADC structures are highly comparable. Thus, in preparation for virtual screening, unprocessed MtbADC (2C45) was.