Dataset Information

The ESX-4 type VII secretion system in required for efficient heme utilization by Mycobacterium tuberculosis

ABSTRACT: In this study our primary objective was to identify unknown components that are required of Mtb Hm acquisition. Herein, we show that the ancestral ESX-4 type VII secretion system (T7SS) which was thought to be inactive in Mtb is required for efficient Hm utilization. We also identified that the culture filtrate proteins Rv0125 and Rv1085c and the alternative sigma factor SigM are necessary of Hm utilization. Finally, we present the first direct evidence that some mycobacterial PPE proteins are pore forming membrane proteins.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Acyrthosiphon Pisum (pea Aphid)

TISSUE(S): Cell Suspension Culture

SUBMITTER: Steven Hartson

LAB HEAD: Avishek Mitra

PROVIDER: PXD036081 | Pride | 2023-01-31

REPOSITORIES: Pride

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Publications

Heme and hemoglobin utilization by Mycobacterium tuberculosis.

Mitra Avishek A Ko Ying-Hui YH Cingolani Gino G Niederweis Michael M

Nature communications 20190918 1

Iron is essential for growth of Mycobacterium tuberculosis (Mtb), but most iron in the human body is stored in heme within hemoglobin. Here, we demonstrate that the substrate-binding protein DppA of the inner membrane Dpp transporter is required for heme and hemoglobin utilization by Mtb. The 1.27 Å crystal structure of DppA shows a tetrapeptide bound in the protein core and a large solvent-exposed crevice for heme binding. Mutation of arginine 179 in this cleft eliminates heme binding to DppA a ...[more]

PMID: 31534126

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Project description:MS/MS analysis of the peanut protein extract (PPE) confirmed the presence of the four major peanut allergens and identified the presence of Ara h 1 isotypes, Ara h 2 isotypes, Ara h 3 isotypes, Ara h 6 isotypes and Ara h 7 isotypes. Allergen-specific immunotherapy (IT) is emerging as a viable option for treatment of peanut allergy. Yet, prophylactic IT remains unexplored despite early introduction of peanut in infancy was shown to prevent allergy. There is a need to understand how allergens interact with the immune system depending on the route of administration, and how different dosages of allergen may protect from sensitisation and a clinical active allergy. Here we compared peanut allergen delivery via the oral, sublingual (SL), intragastric (IG) and subcutaneous (SC) routes for the prevention of peanut allergy in Brown Norway (BN) rats. BN rats were administered PBS or three different doses of PPE via either oral IT (OIT), SLIT, IGIT and SCIT followed by intraperitoneal (IP) injections of PPE to assess the protection from peanut sensitisation. The development of IgE and IgG1 responses to PPE and the major peanut allergens were evaluated by ELISAs. The clinical response to PPE was assessed by an ear swelling test (EST) and proliferation was assessed by stimulating splenocytes with PPE. Low and medium dose OIT (1 and 10 mg) and all doses of SCIT (1, 10, 100 µg) induced sensitisation to PPE, whereas high dose OIT (100 mg), SLIT (10, 100 or 1000 µg) or IGIT (1, 10 and 100 mg) did not. High dose OIT and SLIT as well as high and medium dose IGIT prevented sensitisation from the following IP injections of PPE and suppressed PPE-specific IgE levels in a dose-dependent manner. Hence, administration of peanut protein via different routes confers different risks for sensitisation and protection from peanut allergy development. Overall, the IgE levels toward the individual major peanut allergens followed the PPE-specific IgE levels. Collectively, this study showed that the preventive effect of allergen-specific IT is determined by the interplay between the specific site of PPE delivery for presentation to the immune system, and the allergen quantity, and that targeting and modulating tolerance mechanisms at specific mucosal sites may be a prophylactic strategy for prevention of peanut allergy.

Project description:Increasing experimental evidence supports that Mycobacterium tuberculosis (Mtb) has evolved strategies to survive within the lysosomes from activated macrophages, which may represent a reservoir for persistent mycobacteria. To further our knowledge in Mtb response to the lysosomal environment, we profiled the global transcriptional activity of Mtb in a lysosomal in vitro exposure (LivE) model. At inhibitory conditions of lysosomal SF (iLivE), which did not kill but arrested mycobacterial replication thereby mimicking persistence, Mtb expresses a unique transcriptome, where genes involved in general stress response, metabolic reprogramming, cell wall remodeling, respiration, oxidative stress and dormancy response were found to be significantly modulated. Genes encoding for protein families involved in Mtb virulence including ESAT-6, PE-PPE and Mce proteins were also distinctly regulated. Extensive meta-analysis of the Mtb transcriptomes from iLivE and previously reported ex vivo, in vivo and in vitro stress models revealed most significant overlap between iLivE and primary murine macrophage infection model. Our study also highlighted the α-glucan synthesis pathway and a distinct set of toxin-antitoxin systems as toxicity mechanisms that could be exploited as novel antimicrobial approaches for intra-macrophage persistent bacilli. The specificity in responses generated in the LivE model was supported by the significant number of iLivE genes that did not overlap with any of the previously reported in vitro stress models. Finally, to validate the relevance of the LivE model, rv1258c encoding for the efflux pump protein Tap, was selected from the iLivE Mtb transcriptome for further characterization. An Mtb Δrv1258c mutant was constructed and displayed increased susceptibility to killing by lysosomal SF and by the antimicrobial peptide LL-37 found in lysosomes. Furthermore, Δrv1258c Mtb was attenuated in its ability to survive in primary murine macrophages.

			Action	DRS
	1850_WT_FeCi.raw	Raw
	1850_WT_Hm.raw	Raw
	1850_eccC4_FeCi.raw	Raw
	1850_eccC4_Hm.raw	Raw
	1850_proteinGroups.txt	Txt