Menaquinone synthesis is critical for maintaining mycobacterial viability during exponential growth and recovery from non‐replicating persistence

Abstract

Summary Understanding the basis of bacterial persistence in latent infections is critical for eradication of tuberculosis. Analysis of Mycobacterium tuberculosis mRNA expression in an in vitro model of non-replicating persistence indicated that the bacilli require electron transport chain components and ATP synthesis for survival. Additionally, low μM concentrations of aminoalkoxydiphenylmethane derivatives inhibited both the aerobic growth and survival of non-replicating, persistent M. tuberculosis. Metabolic labeling studies and quantitation of cellular menaquinone levels suggested that menaquinone synthesis, and consequently electron transport, is the target of the aminoalkoxydiphenylmethane derivatives. This hypothesis is strongly supported by the observations that treatment with these compounds inhibits oxygen consumption and that supplementation of growth medium with exogenous menaquinone rescued both growth and oxygen consumption of treated bacilli. In vitro assays indicate that the aminoalkoxydiphenylmethane derivatives specifically inhibit MenA, an enzyme involved in the synthesis of menaquinone. Thus, the results provide insight into the physiology of mycobacterial persistence and a basis for the development of novel drugs that enhance eradication of persistent bacilli and latent tuberculosis.

Essential roles of methionine and S -adenosylmethionine in the autarkic lifestyle of Mycobacterium tuberculosis

“…4A). MenH catalyzes the methylation of demethylmenaquinol to menaquinol, the major electron carrier in Mtb's electron transport chain (25). We detected a significant down-regulation of genes involved in respiration (Fig.…”

“…Also biosynthesis of mycolic acid, an essential component of the mycobacterial cell wall, or menaquinone, the electron carrier in the electron transport chain, have an absolute requirement for SAM (25,43). Many of these processes are validated drug targets in Mtb (25,26,(44)(45)(46). The possibility that the upstream accumulation of a toxic metabolite might contribute to the killing cannot be ruled out, but so far such a compound could not be identified.…”

“…Depletion of methionine and SAM leads to a pervasive metabolic shutdown caused by the inhibition of essential methyltransferasedependent pathways such as biotin biosynthesis and possibly through stalling of translation initiation. Also biosynthesis of mycolic acid, an essential component of the mycobacterial cell wall, or menaquinone, the electron carrier in the electron transport chain, have an absolute requirement for SAM (25,43). Many of these processes are validated drug targets in Mtb (25,26,(44)(45)(46).…”

New Structural Templates for Clinically Validated and Novel Targets in Antimicrobial Drug Research and Development

“…The most common menaquinones contain 7, 8 or 9 isoprene units, however, menaquinones with 4, 5, 6, 10, 11, 12 or 13 isoprene units have been isolated from bacteria. Since it has been demonstrated that menaquinone is crucial for bacterial growth (Dhiman et al 2009;Fujimoto et al 2012) and colony development (Pelchovich et al 2013), it is not a surprise that menaquinone biosynthesis has already been investigated as a target for the development of novel antibiotics (Kurosu and Begari 2010). In the last years a few inhibitors of individual enzymes of menaquinone biosynthesis have been reported (Kurosu and Begari 2010).…”

Identification of arylamine N-acetyltransferase inhibitors as an approach towards novel anti-tuberculars

“…It has been recognized that understanding important metabolic pathways is likely to be a useful route towards new therapies (www.tballiance.org) as a result of the success with an ATPase inhibitor (Diacon et al, 2009). Recent identification of menaquinone biosynthesis as a useful target pathway provides a growing portfolio of potential novel anti-tuberculars (Dhiman et al, 2009). The need for a wide range of candidate targets and molecular classes is insurance for the future (Maxmen and Barry, 2009;Lin et al, 2009).…”