Screening New Anti-TB Drug Targets Of Lead Compound

Tubereulosis(TB), caused by Mycobacterium tuberculosis(MTB), is one of theleading infectious diseases worldwide. It is estimated that nearly one-third populationall over the world have been infected with M. tuberculosis,90%of which are latentlatent infection. In2009, the estimates of the global burden of disease causedby TBwere as follows:9.4million incident cases,14million prevalent cases,1.3milliondeaths. With the emergence and spread of resistant strains, especially multi-drugresistant tuberculosis (MDR) and extensively drug-resistant strains (XDR), not onlymakes of TB treatment cost more, but also more difficult to treatment. Since the mid1990s,World Health Organization promoted DOTS program, the world’s TB infectionrate has declined, but the total global population infected with TB is still increasing.the DOTS program on the treatment of MDR-TB results were not ideal, in large partdue to anti-TB drugs in clinical use limited range. Although the DOTS regiment hasbeen greatly shortted, treatment time is still up to6months, for the patients it is toolong to adhere, which becomes a major source of resistant strains of TB. To deal withthe world severe situation in the tuberculosis treatment and infection, discovery anddevelopment of new anti-TB drugs has become increasingly urgent.Our lab finds a new anti-TB leading compound called T8011by high-throughputscreening of compound library. MTB growth Inhibitory Effect of T8011in vitro issignificant. After the screening by computer simulation of molecular docking, we findthe target of T8011in MTB is probobly Shikimate dehydrogenase (SD). The protein isthe fourth catalytic step shikimate pathway enzyme reaction. As a key enzyme inshikimic acid pathway, SD is essential to the survival of MTB, whileas mammals donot have the shikimic acid pathway. This feature makes the SD become valuable as adrug target.We constructed overexpression SD from H37Rv of M. tuberculosisH37Ra strain, and compared the MIC of T8011against recombinant strains with theMIC of the compound against wild-type strain any change to verify that SD is not thedrug target for the T8011. The results showed no significant difference.Depending on the techniques of two dimensional electrophoresis and MALDI-TOF-TOF, using comparative proteome method, we tried to analyze the possible differences and lead our research to the right direction. Two dimensional gelelectrophoresis (2-DE) was employed to address this problem and global proteome ofH37Ra untreated and treated with T8011were compared. We found32differentialexpressed protein spots, all spots were subjected to MALDI-TOF-TOF analysis and23protein spots were determined successfully identified.7proteins were matchedafter we searched the database,6of which were up-regulated expressed, they wereenoyl-CoA hydratase, MtrA, Rv0504c, heat shock protein X, adenylate kinase,3-oxoacyl-acyl carrier protein synthase II, these four proteins are involved in hypoxia,adenosine phosphate metabolism, fatty acid metabolism and other physiologicalprocesses, and1was down-regulated expressed, thiol peroxidase involved in peroxideclearence, some of them have a chance to become potential drug targets.