Para-aminosalicylic acid acts as an alternative substrate of folate metabolism in Mycobacterium tuberculosis.
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Chakraborty S, Gruber T, Barry CE 3rd, Boshoff HI, Rhee KY
Para-aminosalicylic acid acts as an alternative substrate of folate metabolism in Mycobacterium tuberculosis.
Science. 2013 Jan 4;339(6115):88-91. doi: 10.1126/science.1228980. Epub 2012 Nov 1.
- PubMed ID
- 23118010 [ View in PubMed]
- Abstract
Folate biosynthesis is an established anti-infective target, and the antifolate para-aminosalicylic acid (PAS) was one of the first anti-infectives introduced into clinical practice on the basis of target-based drug discovery. Fifty years later, PAS continues to be used to treat tuberculosis. PAS is assumed to inhibit dihydropteroate synthase (DHPS) in Mycobacterium tuberculosis by mimicking the substrate p-aminobenzoate (PABA). However, we found that sulfonamide inhibitors of DHPS inhibited growth of M. tuberculosis only weakly because of their intracellular metabolism. In contrast, PAS served as a replacement substrate for DHPS. Products of PAS metabolism at this and subsequent steps in folate metabolism inhibited those enzymes, competing with their substrates. PAS is thus a prodrug that blocks growth of M. tuberculosis when its active forms are generated by enzymes in the pathway they poison.