Mycobacterium tuberculosis appears to lack α-ketoglutarate dehydrogenase and encodes pyruvate dehydrogenase in widely separated genes

Jing Tian, Ruslana Bryk, Shuangping Shi, Hediye Erdjument-Bromage, Paul Tempst, Carl Nathan

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75 Scopus citations

Abstract

Mycobacterium tuberculosis (Mtb) persists for prolonged periods in macrophages, where it must adapt to metabolic limitations and oxidative/nitrosative stress. However, little is known about Mtb's intermediary metabolism or antioxidant defences. We recently identified a peroxynitrite reductase-peroxidase complex in Mtb that included products of the genes sucB and Ipd, which are annotated to encode the dihydrolipoamide succinyltransferase (E2) and lipoamide dehydrogenase (E3) components of α-ketoglutarate dehydrogenase (KDH). However, we could detect no KDH activity in Mtb lysates, nor could we reconstitute KDH by combining the recombinant proteins SucA (annotated as the E1 component of KDH), SucB and Lpd. We therefore renamed the sucB product dihydrolipoamide acyltransferase (DlaT). Mtb lysates contained pyruvate dehydrogenase (PDH) activity, which was lost when the dlaT gene (formerly, sucB) was disrupted. Purification of PDH from Mtb yielded AceE, annotated as an E1 component of PDH, along with DlaT and Lpd. Moreover, anti-DlaT antibody coimmunoprecipitated AceE. Finally, recombinant AceE, DlaT and Lpd, although encoded by genes that are widely separated on the chromosome, reconstituted PDH in vitro with Km values typical of bacterial PDH complexes. In sum, Mtb appears to lack KDH. Instead, DlaT and Lpd join with AceE to constitute PDH.

Original languageEnglish (US)
Pages (from-to)859-868
Number of pages10
JournalMolecular Microbiology
Volume57
Issue number3
DOIs
StatePublished - Aug 2005
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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