The Minimal Unit of Infection:<i>Mycobacterium tuberculosis</i>in the Macrophage

VanderVen, Brian C.; Huang, Lu; Rohde, Kyle H.; Russell, David G.

doi:10.1128/microbiolspec.tbtb2-0025-2016

Cited by 40 publications

(18 citation statements)

References 107 publications

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“…Several factors may contribute to the observed intracellular growth defect of M. tuberculosis , producing catalytically inactive TNT. An obvious explanation is that the initiation of necroptosis by TNT-dependent NAD + depletion strongly reduces energy levels (19) and might disrupt phagosome maturation, membrane repair, and other cellular mechanisms required for control of M. tuberculosis growth in infected macrophages (39–42). An additional benefit of TNT-mediated NAD + hydrolysis for M. tuberculosis could be the stimulation of NAD + production by the NAD + salvage pathway.…”

Section: Discussionmentioning

confidence: 99%

The tuberculosis necrotizing toxin is an NAD+ and NADP+ glycohydrolase with distinct enzymatic properties

Tak

Vlach

Garza-Garcia

et al. 2019

Journal of Biological Chemistry

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Upon host infection, Mycobacterium tuberculosis secretes the tuberculosis necrotizing toxin (TNT) into the cytosol of infected macrophages, leading to host cell death by necroptosis. TNT hydrolyzes NAD + in the absence of any exogenous cofactor, thus classifying it as a β-NAD + glycohydrolase. However, TNT lacks sequence similarity with other NAD + hydrolyzing enzymes and lacks the essential motifs involved in NAD + binding and hydrolysis by these enzymes. In this study, we used NMR to examine the enzymatic activity of TNT and found that TNT hydrolyzes NADP + as fast as NAD + but does not cleave the corresponding reduced dinucleotides. This activity of TNT was not inhibited by ADP-ribose or nicotinamide, indicating low affinity of TNT for these reaction products. A selection assay for nontoxic TNT variants in Escherichia coli identified four of six residues in the predicted NAD + -binding pocket and four glycine residues that form a cradle directly below the NAD + -binding site, a conserved feature in the TNT protein family. Site-directed mutagenesis of residues near the predicted NAD + -binding site revealed that Phe 727 , Arg 757 , and Arg 780 are essential for NAD + hydrolysis by TNT. These results identify the NAD + -binding site of TNT. Our findings also show that TNT is an NAD + glycohydrolase with properties distinct from those of other bacterial glycohydrolases. Because many of these residues are conserved within the TNT family, our findings provide insights into understanding the function of the >300 TNT homologs.

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Section: Discussionmentioning

confidence: 99%

The tuberculosis necrotizing toxin is an NAD+ and NADP+ glycohydrolase with distinct enzymatic properties

Tak

Vlach

Garza-Garcia

et al. 2019

Journal of Biological Chemistry

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“…2014; VanderVen et al . 2016); this in cellulo approach is now accepted as being more relevant than classical screening, that is based only on bacteria in vitro .…”

Section: The Spacementioning

confidence: 99%

Mycobacterium tuberculosisinfection of host cells in space and time

Bussi

Gutierrez

2019

FEMS Microbiology Reviews

251

156

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Tuberculosis (TB) caused by the bacterial pathogen Mycobacterium tuberculosis (Mtb) remains one of the deadliest infectious diseases with over a billion deaths in the past 200 years (Paulson 2013). TB causes more deaths worldwide than any other single infectious agent, with 10.4 million new cases and close to 1.7 million deaths in 2017. The obstacles that make TB hard to treat and eradicate are intrinsically linked to the intracellular lifestyle of Mtb. Mtb needs to replicate within human cells to disseminate to other individuals and cause disease. However, we still do not completely understand how Mtb manages to survive within eukaryotic cells and why some cells are able to eradicate this lethal pathogen. Here, we summarise the current knowledge of the complex host cell-pathogen interactions in TB and review the cellular mechanisms operating at the interface between Mtb and the human host cell, highlighting the technical and methodological challenges to investigating the cell biology of human host cell-Mtb interactions.

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“…Thus, both loss of activity against bacterial targets and gain of new target spaces characterize the infected host cell model. The infected macrophage system thus represents a screening platform that encompasses a broad and disease-relevant target range (VanderVen, Huang, Rohde, & Russell, 2016) irrespective of whether the target is of bacterial or host origin.…”

Section: Rationale For Drug Screening Within Infected Host Cells For New Generation Anti-tb Compoundsmentioning

confidence: 99%

Advances in host‐based screening for compounds with intracellular anti‐mycobacterial activity

Subhash

Sundaramurthy

2021

Cellular Microbiology

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Intracellular pathogens interact with host systems in intimate ways to sustain a pathogenic lifestyle. Consequently, these interactions can potentially be targets of hostdirected interventions against infectious diseases. In case of tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis (Mtb), while effective anti-tubercular compounds are available, the long treatment duration and emerging drug resistance necessitate identification of new class of molecules with anti-TB activity, as well as new treatment strategies. A significant part of the effort in finding new anti-TB drugs is focused on bacterial targets in bacterial systems. However, the host environment plays a major role in pathogenesis mechanisms and must be considered actively in these efforts. On the one hand, the bacterial origin targets must be relevant and accessible in the host, while on the other hand, new host origin targets required for the bacterial survival can be targeted. Such targets are good candidates for hostdirected therapeutics, a strategy gaining traction as an adjunct in TB treatment. In this review, we will summarise the screening platforms used to identify compounds with anti-tubercular activities inside different host environments and outline recent technical advances in these platforms. Finally, while the examples given are specific to mycobacteria, the methods and principles outlined are broadly applicable to most intracellular infections.

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The Minimal Unit of Infection:Mycobacterium tuberculosisin the Macrophage

Cited by 40 publications

References 107 publications

The tuberculosis necrotizing toxin is an NAD+ and NADP+ glycohydrolase with distinct enzymatic properties

The tuberculosis necrotizing toxin is an NAD+ and NADP+ glycohydrolase with distinct enzymatic properties

Mycobacterium tuberculosisinfection of host cells in space and time

Advances in host‐based screening for compounds with intracellular anti‐mycobacterial activity

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