Shikimate Kinase: A Potential Target for Development of Novel Antitubercular Agents

Abstract

Tuberculosis (TB) remains the leading cause of mortality due to a bacterial pathogen, Mycobacterium tuberculosis. However, no new classes of drugs for TB have been developed in the past 30 years. Therefore there is an urgent need to develop faster acting and effective new antitubercular agents, preferably belonging to new structural classes, to better combat TB, including MDR-TB, to shorten the duration of current treatment to improve patient compliance, and to provide effective treatment of latent tuberculosis infection. The enzymes in the shikimate pathway are potential targets for development of a new generation of antitubercular drugs. The shikimate pathway has been shown by disruption of aroK gene to be essential for the Mycobacterium tuberculosis. The shikimate kinase (SK) catalyses the phosphorylation of the 3-hydroxyl group of shikimic acid (shikimate) using ATP as a co-substrate. SK belongs to family of nucleoside monophosphate (NMP) kinases. The enzyme is an alpha/beta protein consisting of a central sheet of five parallel beta-strands flanked by alpha-helices. The shikimate kinases are composed of three domains: Core domain, Lid domain and Shikimate-binding domain. The Lid and Shikimate-binding domains are responsible for large conformational changes during catalysis. More recently, the precise interactions between SK and substrate have been elucidated, showing the binding of shikimate with three charged residues conserved among the SK sequences. The elucidation of interactions between MtSK and their substrates is crucial for the development of a new generation of drugs against tuberculosis through rational drug design.

Development of an ESI-LC-MS-Based Assay for Kinetic Evaluation of Mycobacterium tuberculosis Shikimate Kinase Activity and Inhibition

“…MtSK is considered a potential target for the development of novel anti-TB drugs. 34 To date, only a few inhibitors of this enzyme have been identified, mostly through computational techniques 35−42 or through enzyme-coupled assays.…”

Efficient Elimination of Nonstoichiometric Enzyme Inhibitors from HTS Hit Lists

“…The frequency of nonstoichiometric enzyme inhibitors as well as compound characteristics for their identification was initially assessed based on a screening hit list of shikimate kinase 24 inhibitors. Enzyme activity was assayed by detecting both ATP consumption with a luminescence readout 25,26 and also ADP formation with an ADP-specific antibody in a fluorescence polarization readout.…”

New tuberculosis drug development: targeting the shikimate pathway

“…This NADPH-dependent reduction is catalyzed by the SD enzyme, encoded by the aroE gene [55] . The fifth step marks the beginning of the second half of the shikimate pathway, where the reaction involving the shikimate substrate is catalyzed by SK, encoded by the aroK gene, to yield shikimate-3-phosphate (S3P) [56] . This is achieved through the transfer of a phosphate from the ATP co-substrate to the carbon 3-hydroxyl group to form the S3P product.…”

“…Only when a second copy of the aroK gene is present could the disruption of the original chromosomal gene allow continued survival, despite presence of exogenous p -aminobenzoate and aromatic amino-acid supplements [42] . The aroK (Rv2539c) gene is 531 base pairs long, coding for 176 amino acids with a theoretical molecular mass of 18.58 kDa [56] . In 2001, the first of cloning and overexpression of functional M. tuberculosis SK was published [58] .…”