Mycobacterium tuberculosis requires glyoxylate shunt and reverse methylcitrate cycle for lactate and pyruvate metabolism

Abstract

SummaryBacterial nutrition is an essential aspect of host–pathogen interaction. For the intracellular pathogen Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis in humans, fatty acids derived from lipid droplets are considered the major carbon source. However, many other soluble nutrients are available inside host cells and may be used as alternative carbon sources. Lactate and pyruvate are abundant in human cells and fluids, particularly during inflammation. In this work, we study Mtb metabolism of lactate and pyruvate combining classic microbial physiology with a ‘multi‐omics’ approach consisting of transposon‐directed insertion site sequencing (TraDIS), RNA‐seq transcriptomics, proteomics and stable isotopic labelling coupled with mass spectrometry‐based metabolomics. We discovered that Mtb is well adapted to use both lactate and pyruvate and that their metabolism requires gluconeogenesis, valine metabolism, the Krebs cycle, the GABA shunt, the glyoxylate shunt and the methylcitrate cycle. The last two pathways are traditionally associated with fatty acid metabolism and, unexpectedly, we found that in Mtb the methylcitrate cycle operates in reverse, to allow optimal metabolism of lactate and pyruvate. Our findings reveal a novel function for the methylcitrate cycle as a direct route for the biosynthesis of propionyl‐CoA, the essential precursor for the biosynthesis of the odd‐chain fatty acids.

Quantitative analysis of Mycobacterium avium subsp. hominissuis proteome in response to antibiotics and during exposure to different environmental conditions

“…The chloroalkane pathway leads to the acetaldehyde production, which reversibly can be converted into an acetyl-CoA, acetyl-phosphate and pyruvate, and then processed in the TCA cycle for ATP synthesis. On the other hand, the chloroalkene degradation produces substrate for the glyoxylate shunt, which is a modified Krebs cycle and occurs in mycobacteria [27]. The glycoxylate cycle has a central role in the metabolism of pathogenic mycobacteria and, therefore, enzymes associated with the glycoxylate shunt has been exploited for the development of additional anti-TB therapy [28–31].…”

Underestimated Manipulative Roles of Mycobacterium tuberculosis Cell Envelope Glycolipids During Infection

“…In this context, persistence of M. tuberculosis within host cells and in granulomas depends on the bacterial use of lipid metabolic networks such as beta-oxidation, glyoxylate shunt, and the reverse methylcitrate cycle, to break down own and host captured long-chain fatty acids and cholesterol to generate acetyl-CoA and propionyl-CoA (191,192). M. tuberculosis could regulate acetyl-CoA and propionyl-CoA production depending of the status of the host.…”

Proteomics-Based Mechanistic Investigation of Escherichia coli Inactivation by Pulsed Electric Field

“…Notable among the most up-regulated proteins in the PEF treatment group are several enzymes related to the methylcitrate cycle and the TCA cycle, including 2-methylisocitrate lyase (PrpB; W8T6L6), the dual-functional aconitate hydratase B (alsoaconitase, AcnB; A0A2B7LUZ2), 2-methylcitrate dehydratase (PrpD; M9FZM4), and the rate-limiting citrate synthase (prpC; M9GK20). The methylcitrate cycle functions in a similar manner as the TCA cycle, and is responsible for converting propionyl-CoA to pyruvate for further catabolism (Luo et al, 2016; Serafini et al, 2019). As a result, both the TCA cycle and the methylcitrate cycle are functionally connected to and downstream of the β-oxidation of fatty acids.…”