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The Fur-like regulatory protein MAP3773c modulates key metabolic pathways in Mycobacterium avium subsp. paratuberculosis under in-vitro iron starvation

ABSTRACT: Mycobacterium avium subsp. paratuberculosis (MAP) carries MAP3773c, a putative metal regulator, on its genome which is absent in other mycobacteria. Homologues of this gene in enterobacteria have roles in global iron regulation and homeostasis. The role of MAP3773c in regulating intracellular iron in MAP is poorly understood. Functional analysis of DEGs in ΔMAP3773c revealed that pantothenate (Pan) biosynthesis, polysaccharide biosynthesis, sugar metabolism and N-acetyltransferase enhanced intracellular survival genes were downregulated at 30 minutes post-iron starvation whereas ATP-binding cassette (ABC) type metal transporters, putative siderophore biosynthesis, arginine and proline metabolism, PPE, PE family and mammalian cell entry (MCE) genes were upregulated at that same time point. Pathway analysis revealed that the MAP3773c knockout has an impairment in Pan and Coenzyme A (CoA) biosynthesis pathways at 30 minutes post-iron starvation suggesting that the absence of those pathways likely affect overall metabolic processes and cellular functions, which have consequences affecting MAP survival and pathogenesis

ORGANISM(S): Mycobacterium avium subsp. paratuberculosis

PROVIDER: GSE244734 | GEO | 2024/04/18

REPOSITORIES: GEO

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Project description:Iron is an essential cofactor for a wide range of cellular processes. Previous studies have shown that siderophore-mediated uptake and intracellular handling of iron are crucial for virulence of Aspergillus fumigatus. Here we show that the bzip-type transcription factor HapX plays a crucial role in the transcriptional remodeling required for adaption to iron starvation in this opportunistic fungal pathogen. HapX was found to be interconnected in a negative feed-back loop with the previously identified iron regulator SreA: SreA repressed expression of hapX during iron sufficiency and HapX repressed sreA during iron starvation. Genome-wide transcriptional profiling and analysis of selected metabolites (protophorphyrine IX, siderophores and amino acids) indicated extensive metabolic remodeling in response to iron starvation. HapX was found to participate in both, repression and activation of genes during iron starvation. HapX was in particular required for repression of iron-dependent and mitochondrial-localized activities including respiration, TCA cycle, amino acid metabolism, iron-sulfur-cluster biosynthesis and heme biosynthesis. Pathways positively affected by HapX included production of siderophores and the ribotoxin and major allergen AspF1. Analysis of the free amino acid pool revealed HapX-dependent coordination of the production of siderophores with the supply of its precursor ornithine. Consistent with the hapX expression pattern, HapX-deficiency was deleterious with respect to growth rate and conidiation during iron depleted but not iron-replete conditions. HapX-deficiency caused significant attenuation of virulence in a murine model aspergillosis underlining that A. fumigatus faces iron starvation in the host and that the HapX-dependent metabolic reprogramming is therefore crucial for virulence. A. fumigatus 293 and hapX mutants were grown in the presence and absence of iron and in cultures shifted from no iron to iron-containing conditions after 1 h incubation. Hybridizations were performed with biological replicates for wt vs hapX +/- iron. For the iron-shift experiments, there were biological replicates for wt in both conditions and for hapX in -iron but there was only a single biological sample for hapX iron-shift sample. All hybs were performed with flip-dye pairs.

Project description:Because iron toxicity and deficiency are equally life threatening, maintaining intracellular iron levels within a narrow optimal range is critical for nearly all known organisms. However, regulatory mechanisms that establish homeostasis are not well understood in organisms that dwell in environments at the extremes of pH, temperature, and salinity. Under conditions of limited iron, the extremophile Halobacterium salinarum, a salt-loving archaeon, mounts a specific response to scavenge iron for growth. We have identified and characterized the role of two transcription factors (TFs), Idr1 and Idr2, in regulating this important response. An integrated systems analysis of TF knockout gene expression profiles and genome-wide binding locations in the presence and absence of iron has revealed that these TFs operate collaboratively to maintain iron homeostasis. In the presence of iron, Idr1 and Idr2 bind near each other at 24 loci in the genome, where they are both required to repress some genes. In contrast, Idr1 and Idr2 are both necessary to activate other genes in a putative a feed forward loop. Even at loci bound independently, the two TFs target different genes with similar functions in iron homeostasis. We discuss conserved and unique features of the Idr1-Idr2 system in the context of similar systems in organisms from other domains of life. Data in this GEO archive are linked to the publication: Schmid AK, Pan M, Sharma K, Baliga NS.2011. Two transcription factors are necessary for iron homeostasis in a salt-dwelling archaeon.Nucleic Acids Res.39(7):2519-33. The Δura3 parent, Δidr2 and Δidr1, and Δ idr1Δidr2 mutant strains were grown to mid-logarithmic phase (OD600 ~0.4 – 0.8) in CDM with all trace metals except iron. Cultures were split in half and FeSO4 was added to one half, while the other was continued under iron limitation. 8-mL samples were collected from each culture every 20 minutes for 60 minutes (see also experimental design, Supplementary Figure 1, Schmid et al., 2011). RNA from two biological replicate time courses were prepared, averages of these replicates are reported in the published study, whereas data from each replicate are reported here. The zero time point was harvested immediately before the addition of iron. Each Sample is based on two arrrays (one with dye-swap).

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The Fur-like regulatory protein MAP3773c modulates key metabolic pathways in Mycobacterium avium subsp. paratuberculosis under in-vitro iron starvation

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