Open AccessTriosephosphate Isomerase Is Dispensable In Vitro yet Essential for Mycobacterium tuberculosis To Establish Infection
Author(s) -
Carolina Trujillo,
Antje Blumenthal,
Joeli Marrero,
Kyu Y. Rhee,
Dirk Schnappinger,
Sabine Ehrt
Publication year - 2014
Publication title -
mbio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.562
H-Index - 121
eISSN - 2161-2129
pISSN - 2150-7511
DOI - 10.1128/mbio.00085-14
Subject(s) - triosephosphate isomerase , glycolysis , mycobacterium tuberculosis , dihydroxyacetone phosphate , isomerase , biology , biochemistry , metabolic pathway , mutant , tuberculosis , microbiology and biotechnology , enzyme , chemistry , gene , medicine , pathology
Triosephosphate isomerase (TPI) catalyzes the interconversion of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P). This reaction is required for glycolysis and gluconeogenesis, andtpi has been predicted to be essential for growth ofMycobacterium tuberculosis . However, when studying a conditionally regulatedtpi knockdown mutant, we noticed that depletion of TPI reduced growth ofM. tuberculosis in media containing a single carbon source but not in media that contained both a glycolytic and a gluconeogenic carbon source. We used such two-carbon-source media to isolate atpi deletion (Δtpi ) mutant. The Δtpi mutant did not survive with single carbon substrates but grew like wild-type (WT)M. tuberculosis in the presence of both a glycolytic and a gluconeogenic carbon source.13 C metabolite tracing revealed the accumulation of TPI substrates in Δtpi and the absence of alternative triosephosphate isomerases and metabolic bypass reactions, which confirmed the requirement of TPI for glycolysis and gluconeogenesis inM. tuberculosis . The Δtpi strain was furthermore severely attenuated in the mouse model of tuberculosis, suggesting thatM. tuberculosis cannot simultaneously access sufficient quantities of glycolytic and gluconeogenic carbon substrates to establish infection in mice.IMPORTANCE The importance of central carbon metabolism for the pathogenesis ofM. tuberculosis has recently been recognized, but the consequences of depleting specific metabolic enzymes remain to be identified for many enzymes. We investigated triosephosphate isomerase (TPI) because it is central to both glycolysis and gluconeogenesis and had been predicted to be essential for growth ofM. tuberculosis . This work identified metabolic conditions that make TPI dispensable forM. tuberculosis growth in culture and proved thatM. tuberculosis relies on a single TPI enzyme and has no metabolic bypass for the TPI-dependent interconversion of dihydroxyacetone phosphate and glyceraldehyde-3-phosphate in glycolysis and gluconeogenesis. Finally, we demonstrate that TPI is essential for growth of the pathogen in mouse lungs.