Mycobacterium tuberculosis ESAT-6 Exhibits a Unique Membrane-interacting Activity That Is Not Found in Its Ortholog from Non-pathogenic Mycobacterium smegmatis

Leon, Joaquin De; Jiang, Guozhong; Ma, Yue; Rubín, Eric J.; Fortune, Sarah M.; Sun, Jianjun

doi:10.1074/jbc.m112.420869

Cited by 110 publications

(200 citation statements)

References 35 publications

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“…The transcription of the early secreted antigenic target 6 kDa protein (ESAT-6) protein secretion system for the export of EsxA and EsxB was activated in the ΔfakA strain (Table S2). The ESAT-6 system is best known in Mycobacterium tuberculosis where the secreted components are involved in the escape from phagocytic compartment into the cytosol (14). EsxA and EsxB are also involved in S. aureus virulence, although the mechanism is not established (15).…”

Section: [ 14 C]fas To the Two Fakbsmentioning

confidence: 99%

Identification of a two-component fatty acid kinase responsible for host fatty acid incorporation by Staphylococcus aureus

Parsons

Broussard

Bose

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

142

230

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Extracellular fatty acid incorporation into the phospholipids of Staphylococcus aureus occurs via fatty acid phosphorylation. We show that fatty acid kinase (Fak) is composed of two dissociable protein subunits encoded by separate genes. FakA provides the ATP binding domain and interacts with two distinct FakB proteins to produce acyl-phosphate. The FakBs are fatty acid binding proteins that exchange bound fatty acid/acyl-phosphate with fatty acid/acyl-phosphate presented in detergent micelles or liposomes. The ΔfakA and ΔfakB1 ΔfakB2 strains were unable to incorporate extracellular fatty acids into phospholipid. FakB1 selectively bound saturated fatty acids whereas FakB2 preferred unsaturated fatty acids. Affymetrix array showed a global perturbation in the expression of virulence genes in the ΔfakA strain. The severe deficiency in α-hemolysin protein secretion in ΔfakA and ΔfakB1 ΔfakB2 mutants coupled with quantitative mRNA measurements showed that fatty acid kinase activity was required to support virulence factor transcription. These data reveal the function of two conserved gene families, their essential role in the incorporation of host fatty acids by Gram-positive pathogens, and connects fatty acid kinase to the regulation of virulence factor transcription in S. aureus.T he pathway for the uptake and incorporation of host fatty acids (FA) by bacterial pathogens is important to understanding their physiology and determining if type II fatty acid synthesis (FASII) inhibitors will be useful antibacterial therapeutics. FASII is an energy-intensive process, and the advantage of being able to use host FA for membrane assembly obviously allows ATP to be diverted to the synthesis of other macromolecules. Gram-positive pathogens are capable of incorporating extracellular FA into their phospholipids. In species related to Streptococcus agalactiae, extracellular FA can completely replace endogenously synthesized FA, rendering the FASII inhibitors ineffective growth inhibitors if sufficient FA are present (1, 2). In contrast, FASII inhibitors exemplified by the enoyl-acyl carrier protein (ACP) reductase therapeutic AFN-1252 are effective against Staphylococcus aureus, even when extracellular FA are abundant (2, 3). A major impediment to our understanding of this diversity is that the pathway and enzymes responsible for the incorporation of extracellular FA is not established in the Firmicutes. A recent analysis of a ΔplsX knockout strain of S. aureus ruled out a role for either acyl-CoAs or acyl-ACP as intermediates in host FA metabolism and instead provided evidence for the existence of a new enzyme that phosphorylates FA, called FA kinase (Fak) (4) (Fig. 1A). Host FA are phosphorylated by Fak, and the acyl-PO 4 formed is either used by the PlsY glycerol-3-phosphate acyltransferase or converted to acyl-ACP by PlsX. The acyl-ACP may be either elongated by FASII or used by PlsC. Despite the strong evidence for their existence, the genes/proteins that encode this novel enzyme in FA metabolism were previously unidentif...

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Section: [ 14 C]fas To the Two Fakbsmentioning

confidence: 99%

Identification of a two-component fatty acid kinase responsible for host fatty acid incorporation by Staphylococcus aureus

Parsons

Broussard

Bose

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

142

230

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“…It was hypothesized that this process might be pH dependent (147), but it remains unclear if other factors are also involved, because the data obtained from spectroscopic analyses of recombinant ESAT-6 and CFP-10 preparations predicted stability of the complex even under low pH conditions (148). However, a recent study suggested that there were differences among ESAT-6 orthologs from pathogenic and nonpathogenic mycobacterial species in their ability to undergo a conformational change under acidic pH conditions (149). Furthermore, it is not known whether other proteins co-secreted by ESX-1 might also contribute to membrane perforation.…”

Section: Mycobacterial Systems Discovered By Genomics That Are Involvmentioning

confidence: 99%

Mycobacterial Pathogenomics and Evolution

et al. 2014

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Most mycobacterial species are harmless saprophytes, often found in aquatic environments. A few species seem to have evolved from this pool of environmental mycobacteria into major human pathogens, such as Mycobacterium tuberculosis, the agent of tuberculosis, Mycobacterium leprae, the leprosy bacillus, and Mycobacterium ulcerans, the agent of Buruli ulcer. While the pathogenicity of M. ulcerans relates to the acquisition of a large plasmid encoding a polyketide-derived toxin, the molecular mechanisms by which M. leprae or M. tuberculosis have evolved to cause disease are complex and involve the interaction between the pathogen and the host.Here we focus on M. tuberculosis and closely related mycobacteria and discuss insights gained from recent genomic and functional studies. Comparison of M. tuberculosis genome data with sequences from nontuberculous mycobacteria, such as Mycobacterium marinum or Mycobacterium kansasii, provides a perception of the more distant evolution of M. tuberculosis, while the recently accomplished genome sequences of multiple tubercle bacilli with smooth colony morphology, named Mycobacterium canettii, have allowed the ancestral gene pool of tubercle bacilli to be estimated. The resulting findings are instrumental for our understanding of the pathogenomic evolution of tuberculosis-causing mycobacteria. Comparison of virulent and attenuated members of the M. tuberculosis complex has further contributed to identification of a specific secretion pathway, named ESX or Type VII secretion. The molecular machines involved are key elements for mycobacterial pathogenicity, strongly influencing the ability of M. tuberculosis to cope with the immune defense mounted by the host.

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“…The heterodimer was shown to dissociate under acidic conditions, hypothetically inside acidic compartments of the macrophage [59]. On the contrary, studies using recombinant ESAT6 and CFP10 expressed in Escherichia coli failed to detect complex dissociation at acidic pH [60,61]. This discrepancy between native and recombinant proteins could be explained by mycobacterium-specific post-translational modifications on ESAT6 [52].…”

Section: Transport Across Membranes Esx-1 Secretion and Esat6mentioning

confidence: 95%

“…This discrepancy between native and recombinant proteins could be explained by mycobacterium-specific post-translational modifications on ESAT6 [52]. Both recombinant and native ESAT6 lyse artificial membranes [59,[61][62][63][64] due to a hypothetical conformational change of ESAT6 that also facilitated membrane interaction [61]. The helix-turn-helix structure of ESAT6 was shown to insert into membranes upon acidification and to form a membrane-spanning structure, which could lead to membrane lysis [65].…”

Section: Transport Across Membranes Esx-1 Secretion and Esat6mentioning

confidence: 99%

“…Therefore, we speculate that ESAT6 readily integrates into the plasma membrane upon cell contact, and leads to early phagosome rupture and subsequent host cell death ( Figure 12). The requirement of low pH for ESAT6-induced membrane lysis is controversial, with biochemical analyses suggesting that a low pH of 5.0 or lower is a prerequisite for lysis of artificial membranes by recombinant ESAT [61,65], whereas native ESAT6 purified from Mtb could exert lysis at neutral pH but acidic conditions were required for the dissociation of the ESAT6-CFP10 complex [59]. Yet another study demonstrated membrane lysis by both recombinant ESAT6 and a ESAT6-CFP10 dimer at neutral pH [410].…”

Section: Esat6 Esat6 Esat6 Esat6mentioning

confidence: 99%

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Interplay of human macrophages and Mycobacterium tuberculosis phenotypes

Raffetseder¹

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Mycobacterium tuberculosis ESAT-6 Exhibits a Unique Membrane-interacting Activity That Is Not Found in Its Ortholog from Non-pathogenic Mycobacterium smegmatis

Cited by 110 publications

References 35 publications

Identification of a two-component fatty acid kinase responsible for host fatty acid incorporation by Staphylococcus aureus

Identification of a two-component fatty acid kinase responsible for host fatty acid incorporation by Staphylococcus aureus

Mycobacterial Pathogenomics and Evolution

Interplay of human macrophages and Mycobacterium tuberculosis phenotypes

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