Functioning of Mycobacterial Heat Shock Repressors Requires the Master Virulence Regulator PhoP

Sevalkar, Ritesh Rajesh; Arora, Divya; Singh, Prabhat Ranjan; Singh, Ranjeet; Nandicoori, Vinay Kumar; Karthikeyan, Subramanian; Sarkar, Dibyendu

doi:10.1128/jb.00013-19

Cited by 17 publications

(18 citation statements)

References 37 publications

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“…5). This is in sharp contrast to recently reported PhoP-HspR and PhoP-HrcA interactions, where PhoPN was shown to interact with the C-terminal ends of mycobacterial heat shock repressors (45). Although the phosphorylation of either of the regulators does not seem to influence PhoP-DosR protein-protein contacts (see Fig.…”

Section: Discussioncontrasting

confidence: 96%

Metabolic Switching of Mycobacterium tuberculosis during Hypoxia Is Controlled by the Virulence Regulator PhoP

2020

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Mycobacterium tuberculosis retains the ability to establish an asymptomatic latent infection. A fundamental question in mycobacterial physiology is to understand the mechanisms involved in hypoxic stress, a critical player in persistence. Here, we show that the virulence regulator PhoP responds to hypoxia, the dormancy signal, and effectively integrates hypoxia with nitrogen metabolism. We also provide evidence to demonstrate that both under nitrogen limiting conditions and during hypoxia, phoP locus controls key genes involved in nitrogen metabolism. Consistently, under hypoxia a ΔphoP strain shows growth attenuation even with surplus nitrogen, the alternate electron acceptor, and complementation of the mutant restores bacterial growth. Together, our observations provide new biological insights into the role of PhoP in integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator DosR. The results have significant implications on the mechanism of intracellular survival and growth of the tubercle bacilli under a hypoxic environment within the phagosome. IMPORTANCE M. tuberculosis retains the unique ability to establish an asymptomatic latent infection. To understand the mechanisms involved in hypoxic stress which play a critical role in persistence, we show that the virulence regulator PhoP is linked to hypoxia, the dormancy signal. In keeping with this, phoP was shown to play a major role in M. tuberculosis growth under hypoxia even in the presence of surplus nitrogen, the alternate electron acceptor. Our results showing regulation of hypoxia-responsive genes provide new biological insights into role of the virulence regulator in metabolic switching by sensing hypoxia and integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator DosR.

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Section: Discussioncontrasting

confidence: 96%

Metabolic Switching of Mycobacterium tuberculosis during Hypoxia Is Controlled by the Virulence Regulator PhoP

2020

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“…5). This is in sharp contrast to recently-reported PhoP-HspR and PhoP-HrcA interactions where PhoPN was shown to interact with the C-terminal end of the mycobacterial heat-shock repressors (43). Although phosphorylation of either of the regulators does not seem to influence PhoP-DosR protein-protein contacts (Fig.…”

Section: Discussioncontrasting

confidence: 99%

Metabolic switching ofMycobacterium tuberculosisduring hypoxia is controlled by the virulence regulator PhoP

Singh

Kumar

Sarkar

2019

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25Mycobacterium tuberculosis (Mtb) retains the unique ability to establish an asymptomatic 26 latent infection. A fundamental question in mycobacterial physiology is to understand the 27 mechanisms involved in hypoxic stress, a critical player in persistence. Here, we show that the 28 virulence regulator PhoP responds to hypoxia, the dormancy signal and effectively integrates 29 hypoxia with nitrogen metabolism. We also provide evidence to demonstrate that both under 30 nitrogen limiting conditions and during hypoxia, phoP locus controls key genes involved in 31 nitrogen metabolism. Consistently, under hypoxia phoP shows growth attenuation even with 32 surplus nitrogen, the alternate electron acceptor, and complementation of the mutant restores 33 bacterial growth. Together, our observations provide new biological insights into the role of 34 PhoP in integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator 35DosR. The results have significant implications on the mechanism of intracellular survival and 36 growth of the tubercle bacilli under a hypoxic environment within the phagosome. 37 38 Importance 39Mtb retains the unique ability to establish an asymptomatic latent infection. To understand the 40 mechanisms involved in hypoxic stress which plays a critical role in persistence, we show that 41 the virulence regulator PhoP responds to hypoxia, the dormancy signal. In keeping with this, 42 phoP was shown to play a major role in Mtb growth under hypoxia even in presence of surplus 43 nitrogen, the alternate electron acceptor. Our results showing regulation of hypoxia-responsive 44 genes provide new biological insights into role of the virulence regulator in metabolic switching 45 by sensing hypoxia and integrating nitrogen metabolism with hypoxia by the assistance of the 46 hypoxia regulator DosR. 47 48 49 A hallmark of tuberculosis is the unique ability of Mtb to establish an asymptomatic 50 latent infection and persist within granulomas in a dormant form, sometimes for a very long 51 time, before reactivation to cause the active disease. As survival and persistence in this 52 environment depends on the sensing of signals and ability to induce a robust adaptive response, 53 one of the major aspects to understand latent TB relates to understanding molecular mechanism 54 of adaptation of the tubercle bacilli in response to environmental stress. 55 56 Despite its requirement of oxygen for growth, during latency Mtb can survive without 57 oxygen for a surprisingly long time. Thus, two in vivo conditions are often linked to latent TB. 58These are hypoxia and exposure to immune effectors such as nitric oxide (NO) (1-3). The ability 59 to produce reactive nitrogen species (RNS) by host-inducible nitric oxide synthase (iNOS) 60 contributes to TB infections by its effect on both the host and the pathogen (4). Therefore, 61 functional iNOS expression could be detected in the lung macrophages of human TB patients (5, 62 6). Consistently, hypoxia and nitric oxide dependent bacterial adaptation...

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“…It is worth mentioning that in several other bacterial species, the regulons of different heat-shock repressors partially overlap, resulting in some genes being simultaneously controlled by two regulatory proteins. For example, the groESL promoter transcription is controlled by the concerted action of HrcA and CtsR in Streptococcus pneumoniae and Staphylococcus aureus [ 32 , 33 ], and the acr2 and groEL2 genes in Mycobacterium tuberculosis are regulated by the interplay among PhoP, HrcA and HspR [ 34 , 35 ]. In this latter example, the virulence-associated protein PhoP acts as a nodal regulator, able to alternatively interact with and recruit in vivo the HrcA and HspR repressors within the target genes and regulate the stress-specific expression of heat-shock proteins.…”

Section: Discussionmentioning

confidence: 99%

Cooperative Regulation of Campylobacter jejuni Heat-Shock Genes by HspR and HrcA

2020

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The heat-shock response is defined by the transient gene-expression program that leads to the rapid accumulation of heat-shock proteins. This evolutionary conserved response aims at the preservation of the intracellular environment and represents a crucial pathway during the establishment of host–pathogen interaction. In the food-borne pathogen Campylobacter jejuni two transcriptional repressors, named HspR and HrcA, are involved in the regulation of the major heat-shock genes. However, the molecular mechanism underpinning HspR and HrcA regulatory function has not been defined yet. In the present work, we assayed and mapped the HspR and HrcA interactions on heat-shock promoters by high-resolution DNase I footprintings, defining their regulatory circuit, which governs C. jejuni heat-shock response. We found that, while DNA-binding of HrcA covers a compact region enclosing a single inverted repeat similar to the so-called Controlling Inverted Repeat of Chaperone Expression (CIRCE) sequence, HspR interacts with multiple high- and low-affinity binding sites, which contain HspR Associated Inverted Repeat (HAIR)-like sequences. We also explored the DNA-binding properties of the two repressors competitively on their common targets and observed, for the first time, that HrcA and HspR can directly interact and their binding on co-regulated promoters occurs in a cooperative manner. This mutual cooperative mechanism of DNA binding could explain the synergic repressive effect of HspR and HrcA observed in vivo on co-regulated promoters. Peculiarities of the molecular mechanisms exerted by HspR and HrcA in C. jejuni are compared to the closely related bacterium H. pylori that uses homologues of the two regulators.

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Functioning of Mycobacterial Heat Shock Repressors Requires the Master Virulence Regulator PhoP

Cited by 17 publications

References 37 publications

Metabolic Switching of Mycobacterium tuberculosis during Hypoxia Is Controlled by the Virulence Regulator PhoP

Metabolic Switching of Mycobacterium tuberculosis during Hypoxia Is Controlled by the Virulence Regulator PhoP

Metabolic switching ofMycobacterium tuberculosisduring hypoxia is controlled by the virulence regulator PhoP

Cooperative Regulation of Campylobacter jejuni Heat-Shock Genes by HspR and HrcA

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