Essentiality of mmpL3 and impact of its silencing on Mycobacterium tuberculosis gene expression

Abstract

MmpL3 is an inner membrane transporter of Mycobacterium tuberculosis responsible for the export of trehalose momomycolate, a precursor of the mycobacterial outer membrane component trehalose dimycolate (TDM), as well as mycolic acids bound to arabinogalactan. MmpL3 represents an emerging target for tuberculosis therapy. In this paper, we describe the construction and characterization of an mmpL3 knockdown strain of M. tuberculosis. Downregulation of mmpL3 led to a stop in bacterial division and rapid cell death, preceded by the accumulation of TDM precursors. MmpL3 was also shown to be essential for growth in monocyte-derived human macrophages. Using RNA-seq we also found that MmpL3 depletion caused up-regulation of 47 genes and down-regulation of 23 genes (at least 3-fold change and false discovery rate ≤1%). Several genes related to osmoprotection and metal homeostasis were induced, while several genes related to energy production and mycolic acids biosynthesis were repressed suggesting that inability to synthesize a correct outer membrane leads to changes in cellular permeability and a metabolic downshift.

Narrow-spectrum antibacterial agents

“…This transporter is essential in mycobacteria, and is specific to Actinobacteria, 40, 48 making it a promising target for the development of narrow spectrum antibacterial agents for mycobacterial pathogens. A series of indole-containing compounds have been developed as inhibitors of this transporter, and have demonstrated potent in vitro antibacterial activity against M. tuberculosis 49 along with several species of non-tuberculosis mycobacteria (NTM), which are a growing healthcare problem.…”

An overview of new antitubercular drugs, drug candidates, and their targets

“…Mycobacterial membranes protein large (MmpL) are a family of proteins that plays critical roles in substrate transport across the inner membrane of mycobacteria for building the unique mycobacterial cell wall . These proteins export mycolic acids bound to arabinogalactan and trehalose monomycolate for the synthesis of trehalose dimycolate . The necessity of MmpL3 for the viability of M. tuberculosis has made it a successful target in the last decade .…”

“…191 These proteins export mycolic acids bound to arabinogalactan and trehalose monomycolate for the synthesis of trehalose BAHUGUNA AND RAWAT | 279 dimycolate. 192 The necessity of MmpL3 for the viability of M. tuberculosis has made it a successful target in the last decade. 193 There are 13 MmpL proteins encoded in M. tuberculosis.…”

Structure‐Based Design and Synthesis of Piperidinol‐Containing Molecules as New Mycobacterium abscessus Inhibitors

“…Thanks to the selection of spontaneous resistant mutants and following whole‐genome sequencing, single nucleotide polymorphisms (SNP) were identified in MAB_4508 . This gene encodes the mycolic acid transporter MmpL3 that was shown to be essential for Mycobacterium smegmatis and M. tuberculosis survival . Like other MmpL, MmpL3 is a transmembrane protein belonging to the Resistance‐Nodulation‐Cell division (RND) permeases .…”