Construction And Application Of Mycobacterium Tuberculosis Isocitrate Lyase-based High-throughput Drug Screening Model

Isocitrate lyase (ICL) catalyses the first committed step of the glyoxylate bypass, which reversibly cleaves isocitrate into succinate and glyoxylate. This pathway is distributed in a wide range of pathogen, and it plays a vital role in the pathogenesis of Mycobacterium tuberculosis (MTB). ICL involved in this cycle was identified as an attractive drug target of development. In this article, ICL was cloned, expressed and purified, and a high-throughput screen (HTS) has been developed to screening active extracts derived from traditional Chinese medicines (TCMs), which have the inhibition against ICL and could be developed as anti-tuberculosis agents with improved pharmacological properties. A colorimetric assay based on the formation of glyoxylate-phenylhydrazone was used to measure the ICL activity. A collection of 465 extracts derived from TCMs was screened and two extracts of XHD-1 and XHD-2 showed the inhibition against ICL with IC₅₀ 0.0477±0.0169 and 0.0182±0.0009 mg/ml, respectively, and the assay exhibited signal to noise (S/N) of 12.7 and T factor of 0.72, respectively. In conclusion, the S/N and Z factor indicates that the assay we developed was suitable for high-throughput screening, and the extracts of XHD-1 and XHD-2 can inhibitICL.