Transcriptional regulation of fatty acid biosynthesis in mycobacteria

Abstract

SUMMARY The main purpose of our study is to understand how mycobacteria exert control over the biosynthesis of their membrane lipids and find out the key components of the regulatory network that control fatty acid biosynthesis at the transcriptional level. In this paper we describe the identification and purification of FasR, a transcriptional regulator from Mycobacterium sp. that controls the expression of the fatty acid synthase (fas) and the 4-phosphopantetheinyl transferase (acpS) encoding genes, whose products are involved in the fatty acid and mycolic acid biosynthesis pathways. In vitro studies demonstrated that fas and acpS genes are part of the same transcriptional unit and that FasR specifically binds to three conserved operator sequences present in the fas-acpS promoter region (Pfas). The construction and further characterization of a fasR conditional mutant confirmed that FasR is a transcriptional activator of the fas-acpS operon and that this protein is essential for mycobacteria viability. Furthermore, the combined used of Pfas-lacZ fusions in different fasR backgrounds and electrophoretic mobility shift assays experiments, strongly suggested that long-chain acyl-CoAs are the effector molecules that modulate the affinity of FasR for its DNA binding sequences and therefore the expression of the essential fas-acpS operon.

Mycobacterium tuberculosisFasR senses long fatty acyl-CoA through a tunnel, inducing DNA-dissociation via a transmission spine

“…1), a tunnel that is conspicuously opened on both ends. This singular solution has evolved to lodge the kind of acylated chains of 20 and more carbons that inhibit FasR binding to its cognate DNA (7).…”

Evolution of Mycolic Acid Biosynthesis Genes and Their Regulation during Starvation in Mycobacterium tuberculosis

“…A few transcription regulators that directly regulate the biosynthesis genes have been identified. FasR regulates the expression of the fas gene (15), while MabR (16) and FadR (17) regulate the expression of the fabD-accD6 cluster, the fasII operon (Fig. 1B).…”

Analysis of coenzyme A activated compounds in actinomycetes

“…Our laboratory is actively studying lipid metabolism in mycobacteria and related actinomycetes (Rodríguez et al 2001; Gago et al 2006; Kurth et al 2009; Salzman et al 2010; Mondino et al 2013; Comba et al 2014; Menendez-Bravo et al 2014; Bazet Lyonnet et al 2014). The structure and biosynthesis of the unique fatty acids found in the complex lipids that form the M. tuberculosis cell envelope has been the subject of intense research efforts (Daffé 2008), primarily because the enzymes involved in their metabolism offer attractive and selective targets for the development of antimycobacterial drugs or for their use in biotechnological processes (Zhang 2005; Menendez-Bravo et al 2014).…”

“…Apart from participating in numerous metabolic pathways as substrates and intermediates (Haynes 2011), CoA and a number of its thioester derivatives, such as acetyl-CoA, can also regulate directly the activity of proteins by allosteric mechanisms and by affecting protein acetylation reactions (Shi and Tu 2015). It has also been found that CoA-thioesters have the ability to regulate gene expression by modulating the affinity of transcription factors for their target DNA (Black et al 2000; Mondino et al 2013). …”