Methods and Compositions for Specific Inhibition of Protein Splicing by Small Molecules for the treatment of Turberculosis

Boston Biomedical Research Institute
posted on 05/12/2011

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Background: In Mycobacterium tuberculosis, two important proteins of nucleic acid metabolism, DnaB and RecA, are interrupted by inteins that must be excised by protein splicing before the proteins can function.
The DnaB protein is a helicase that plays an essential role in DNA replication and the RecA protein plays a key role in DNA repair, which contributes to the intracellular survival of M. tuberculosis in host macrophages.
Neither of these proteins has been the target for antibiotics in any organism, but the fact both proteins are interrupted by inteins, whose excision is required for protein function, makes these inteins effective antimycobacterial targets.
Because the inteins that promote the splicing of DnaB and RecA are quite similar, a class of protein splicing inhibitors should exist that interfere with the formation of functional DnaB as well as RecA proteins and thereby inhibit both DNA replication and DNA repair in M. tuberculosis
We have developed a highly sensitive in vitro assay systems for protein splicing mediated by the DnaB and RecA inteins, based on the measurement of fluorescence, and adapted this assay to the high-throughput screening system for protein splicing inhibitors.
At this stage, we have screened more than 60,000 compounds derived from eight different compound libraries and have obtained 196 positives, of which about 60 have passed secondary in vitro screening.
In silico analysis suggest that a significant fraction of these have drug-like character.
Advantages: This could be a breakthrough in the treatment of multidrug-resistant tuberculosis in combination with other anti-tuberculosis drugs.
If the emergence of resistant against protein splicing inhibitors is slow, which will have to be determined experimentally, these could perhaps also used as a free-standing therapy, which would be of significant advantage both in terms of drug administration and cost.
Status: US. patent application filed October, 2004