scholarly journals In vivo growth of Staphylococcus lugdunensis is facilitated by the concerted function of heme and non-heme iron acquisition mechanisms

2022 ◽  
Author(s):  
Ronald S Flannagan ◽  
Jeremy R Brozyna ◽  
Brijesh Kumar ◽  
Lea A Adolf ◽  
Jeffrey J Power ◽  
...  
Keyword(s):  
Iron Acquisition ◽  
Stress Hormones ◽  
Systemic Infection ◽  
Culture Conditions ◽  
Heme Iron ◽  
Mammalian Host ◽  
Staphylococcus Lugdunensis ◽  
Non Heme Iron ◽  
Gene Acquisition

Acquisition of iron underpins the ability of pathogens to cause disease and Staphylococcus lugdunensis has increasingly been recognized as a pathogen that can cause serious infection. In this study, we sought to address the knowledge gap that exists regarding the iron acquisition mechanisms employed by S. lugdunensis, especially during infection of the mammalian host. Here we show that S. lugdunensis utilizes diverse genome encoded iron acquisition mechanisms to satisfy its need for this nutrient. Indeed, S. lugdunensis can usurp hydroxamate siderophores, and staphyloferrin A and B from S. aureus, using the fhuC ATPase-encoding gene. Acquisition of catechol siderophores and catecholamine stress hormones necessitates the presence of the sst-1 transporter-encoding locus, but not the sst-2 locus. Iron-dependent growth in acidic culture conditions necessitates the feoAB locus. Heme iron is acquired via expression of the iron-regulated surface determinant (isd) locus. During systemic infection of mice we demonstrate that while S. lugdunensis does not cause overt illness, it does colonize and proliferate to high numbers in the kidneys. By combining mutations in the various iron acquisition loci, we further demonstrate that only a strain mutated for all of isd, fhuC, sst-1, and feo, versus combination mutants carrying wild type copies of any one of those loci, was attenuated in its ability to proliferate to high numbers in kidneys. Taken together our data reveal that S. lugdunensis requires a repertoire of both heme and non-heme iron acquisition mechanisms to proliferate during systemic infection of mammals

scholarly journals In Vivo-Induced Genes in Pseudomonas aeruginosa

2000 ◽  
Vol 68 (4) ◽  
pp. 2359-2362 ◽  
Author(s):  
Martin Handfield ◽  
Dario E. Lehoux ◽  
François Sanschagrin ◽  
Michael J. Mahan ◽  
Donald E. Woods ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Chronic Infection ◽  
Iron Acquisition ◽  
Systemic Infection ◽  
Lung Model ◽  
Rat Lung ◽  
Reading Frame ◽  
Sequence Identity ◽  
Induced Genes

ABSTRACT In vivo expression technology was used for testingPseudomonas aeruginosa in the rat lung model of chronic infection and in a mouse model of systemic infection. Three of the eight ivi proteins found showed sequence identity to known virulence factors involved in iron acquisition via an open reading frame (called pvdI) implicated in pyoverdine biosynthesis, membrane biogenesis (FtsY), and adhesion (Hag2).

scholarly journals RNA Enrichment Method for Quantitative Transcriptional Analysis of Pathogens In Vivo Applied to the Fungus Candida albicans

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Sara Amorim-Vaz ◽  
Van Du T. Tran ◽  
Sylvain Pradervand ◽  
Marco Pagni ◽  
Alix T. Coste ◽  
...  
Keyword(s):  
Candida Albicans ◽  
High Resolution ◽  
Galleria Mellonella ◽  
Iron Acquisition ◽  
Transcriptional Response ◽  
Systemic Infection ◽  
Microbial Pathogens ◽  
Transcriptional Analysis ◽  
Content Type

ABSTRACT In vivo transcriptional analyses of microbial pathogens are often hampered by low proportions of pathogen biomass in host organs, hindering the coverage of full pathogen transcriptome. We aimed to address the transcriptome profiles of Candida albicans, the most prevalent fungal pathogen in systemically infected immunocompromised patients, during systemic infection in different hosts. We developed a strategy for high-resolution quantitative analysis of the C. albicans transcriptome directly from early and late stages of systemic infection in two different host models, mouse and the insect Galleria mellonella. Our results show that transcriptome sequencing (RNA-seq) libraries were enriched for fungal transcripts up to 1,600-fold using biotinylated bait probes to capture C. albicans sequences. This enrichment biased the read counts of only ~3% of the genes, which can be identified and removed based on a priori criteria. This allowed an unprecedented resolution of C. albicans transcriptome in vivo, with detection of over 86% of its genes. The transcriptional response of the fungus was surprisingly similar during infection of the two hosts and at the two time points, although some host- and time point-specific genes could be identified. Genes that were highly induced during infection were involved, for instance, in stress response, adhesion, iron acquisition, and biofilm formation. Of the in vivo-regulated genes, 10% are still of unknown function, and their future study will be of great interest. The fungal RNA enrichment procedure used here will help a better characterization of the C. albicans response in infected hosts and may be applied to other microbial pathogens. IMPORTANCE Understanding the mechanisms utilized by pathogens to infect and cause disease in their hosts is crucial for rational drug development. Transcriptomic studies may help investigations of these mechanisms by determining which genes are expressed specifically during infection. This task has been difficult so far, since the proportion of microbial biomass in infected tissues is often extremely low, thus limiting the depth of sequencing and comprehensive transcriptome analysis. Here, we adapted a technology to capture and enrich C. albicans RNA, which was next used for deep RNA sequencing directly from infected tissues from two different host organisms. The high-resolution transcriptome revealed a large number of genes that were so far unknown to participate in infection, which will likely constitute a focus of study in the future. More importantly, this method may be adapted to perform transcript profiling of any other microbes during host infection or colonization.

Expression of the DMT1 (NRAMP2/DCT1) iron transporter in mice with genetic iron overload disorders

Blood ◽  
2001 ◽  
Vol 97 (4) ◽  
pp. 1138-1140 ◽  
Author(s):  
François Canonne-Hergaux ◽  
Joanne E. Levy ◽  
Mark D. Fleming ◽  
Lynne K. Montross ◽  
Nancy C. Andrews ◽  
...  
Keyword(s):  
Iron Deficiency ◽  
Iron Overload ◽  
Mouse Models ◽  
Brush Border ◽  
Knockout Mice ◽  
Heme Iron ◽  
Iron Loading ◽  
Non Heme Iron ◽  
Iron Transporter

Abstract Iron overload is highly prevalent, but its molecular pathogenesis is poorly understood. Recently, DMT1 was shown to be a major apical iron transporter in absorptive cells of the duodenum. In vivo, it is the only transporter known to be important for the uptake of dietary non-heme iron from the gut lumen. The expression and subcellular localization of DMT1 protein in 3 mouse models of iron overload were examined: hypotransferrinemic (Trfhpx) mice, Hfeknockout mice, and B2m knockout mice. Interestingly, in Trfhpx homozygotes, DMT1 expression was strongly induced in the villus brush border when compared to control animals. This suggests that DMT1 expression is increased in response to iron deficiency in the erythron, even in the setting of systemic iron overload. In contrast, no increase was seen in DMT1 expression in animals with iron overload resembling human hemochromatosis. Therefore, it does not appear that changes in DMT1 levels are primarily responsible for iron loading in hemochromatosis.

scholarly journals Inactivation of genes in oxidative respiration and iron acquisition pathways in pediatric clinical isolates of Small colony variant Enterobacteriaceae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander L. Greninger ◽  
Amin Addetia ◽  
Yue Tao ◽  
Amanda Adler ◽  
Xuan Qin
Keyword(s):  
Iron Acquisition ◽  
Culture Conditions ◽  
Single Nucleotide Variants ◽  
Genetic Rescue ◽  
Small Colony Variant ◽  
E Coli ◽  
Small Colony ◽  
Oxidative Respiration

AbstractIsolation of bacterial small colony variants (SCVs) from clinical specimens is not uncommon and can fundamentally change the outcome of the associated infections. Bacterial SCVs often emerge with their normal colony phenotype (NCV) co-isolates in the same sample. The basis of SCV emergence in vivo is not well understood in Gram-negative bacteria. In this study, we interrogated the causal genetic lesions of SCV growth in three pairs of NCV and SCV co-isolates of Escherichia coli, Citrobacter freundii, and Enterobacter hormaechei. We confirmed SCV emergence was attributed to limited genomic mutations: 4 single nucleotide variants in the E. coli SCV, 5 in C. freundii, and 8 in E. hormaechei. In addition, a 10.2 kb chromosomal segment containing 11 genes was deleted in the E. hormaechei SCV isolate. Each SCV had at least one coding change in a gene associated with bacterial oxidative respiration and another involved in iron capture. Chemical and genetic rescue confirmed defects in heme biosynthesis for E. coli and C. freundii and lipoic acid biosynthesis in E. hormaachei were responsible for the SCV phenotype. Prototrophic growth in all 3 SCV Enterobacteriaceae species was unaffected under anaerobic culture conditions in vitro, illustrating how SCVs may persist in vivo.

scholarly journals In vivo evaluation of heme and non-heme iron content and neuronal density in human basal ganglia

NeuroImage ◽  
2021 ◽  
pp. 118012
Author(s):  
Dmitriy A Yablonskiy ◽  
Jie Wen ◽  
Satya V.V.N. Kothapalli ◽  
Alexander L Sukstanskii
Keyword(s):  
Basal Ganglia ◽  
Iron Content ◽  
Heme Iron ◽  
In Vivo Evaluation ◽  
Neuronal Density ◽  
Non Heme Iron

Ultrastructural Study of a differentiating human colon carcinoma cell line

1990 ◽  
Vol 48 (3) ◽  
pp. 208-209
Author(s):  
Sylvie Polak-Charcon ◽  
Mehrdad Hekmati ◽  
Yehuda Ben Shaul
Keyword(s):  
Cell Line ◽  
Morphological Changes ◽  
Secretory Granules ◽  
Human Colon ◽  
Cell Types ◽  
Culture Conditions ◽  
Morphological Evidence ◽  
Human Colon Carcinoma Cell ◽  
Colon Cell

The epithelium of normal human colon mucosa “in vivo” exhibits a gradual pattern of differentiation as undifferentiated stem cells from the base of the crypt of “lieberkuhn” rapidly divide, differentiate and migrate toward the free surface. The major differentiated cell type of the intestine observed are: absorptive cells displaying brush border, goblet cells containing mucous granules, Paneth and endocrine cells containing dense secretory granules. These different cell types are also found in the intestine of the 13-14 week old embryo.We present here morphological evidence showing that HT29, an adenocarcinoma of the human colon cell line, can differentiate into various cell types by changing the growth and culture conditions and mimic morphological changes found during development of the intestine in the human embryo.HT29 cells grown in tissue-culture dishes in DMEM and 10% FCS form at late confluence a multilayer of morphologically undifferentiated cell culture covered with irregular microvilli, and devoid of tight junctions (Figs 1-3).

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

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