scholarly journals Mechanisms and heterogeneity of mineral use by natural colonies of the cyanobacterium Trichodesmium

2020 ◽  
Author(s):  
Noelle A. Held ◽  
Kevin M. Sutherland ◽  
Eric A. Webb ◽  
Matthew R. McIlvin ◽  
Natalie R. Cohen ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Iron Acquisition ◽  
Dust Particles ◽  
Iron Storage ◽  
Global Impact ◽  
Mineral Particles ◽  
Nickel Copper ◽  
Iron Nickel ◽  
Essential Nutrient ◽  
Iron Storage Protein

AbstractThe keystone marine nitrogen fixer Trichodesmium thrives in high dust environments, and while experimental observations suggest that Trichodesmium colonies can access the essential nutrient iron from dust particles, it is not known the extent to which this occurs in the field. Here we demonstrate that Trichodesmium colonies actively process mineral particles in nature with direct molecular impacts. Microscopy and synchrotron-based imaging demonstrated heterogeneous associations with particles consistent with iron oxide and iron silicate minerals. Metaproteomic analysis of individual colonies revealed enrichment of biogeochemically-relevant proteins including photosynthesis proteins and metalloproteins containing iron, nickel, copper and zinc when particles were present. The iron-storage protein ferritin was particularly enriched implying accumulation of particle-derived iron, and multiple iron acquisition pathways including Fe(II), Fe(III), and Fe-siderophore transporters were engaged, including evidence of superoxide-driven particle dissolution. While the particles clearly provided iron, there was also evidence that the concentrated metals had toxic effects. The molecular mechanisms allowing Trichodesmium to interact with particulate minerals are fundamental to its success and global impact on nitrogen biogeochemistry, and may contribute to the leaching of particulate trace metals with implications for global iron and carbon cycling.

scholarly journals Mechanisms and heterogeneity of in situ mineral processing by the marine nitrogen fixer Trichodesmium revealed by single-colony metaproteomics

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Noelle A. Held ◽  
Kevin M. Sutherland ◽  
Eric A. Webb ◽  
Matthew R. McIlvin ◽  
Natalie R. Cohen ◽  
...  
Keyword(s):  
Trace Metals ◽  
Iron Acquisition ◽  
Dust Particles ◽  
Metal Exposure ◽  
Sampling Location ◽  
Iron Storage ◽  
Molecular Responses ◽  
Nitrogen Fixer ◽  
Nickel Copper ◽  
In The Wild

AbstractThe keystone marine nitrogen fixer Trichodesmium thrives in high-dust environments. While laboratory investigations have observed that Trichodesmium colonies can access the essential nutrient iron from dust particles, less clear are the biochemical strategies underlying particle–colony interactions in nature. Here we demonstrate that Trichodesmium colonies engage with mineral particles in the wild with distinct molecular responses. We encountered particle-laden Trichodesmium colonies at a sampling location in the Southern Caribbean Sea; microscopy and synchrotron-based imaging then demonstrated heterogeneous associations with iron oxide and iron-silicate minerals. Metaproteomic analysis of individual colonies by a new low-biomass approach revealed responses in biogeochemically relevant proteins including photosynthesis proteins and metalloproteins containing iron, nickel, copper, and zinc. The iron-storage protein ferritin was particularly enriched implying accumulation of mineral-derived iron, and multiple iron acquisition pathways including Fe(II), Fe(III), and Fe-siderophore transporters were engaged. While the particles provided key trace metals such as iron and nickel, there was also evidence that Trichodesmium was altering its strategy to confront increased superoxide production and metal exposure. Chemotaxis regulators also responded to mineral presence suggesting involvement in particle entrainment. These molecular responses are fundamental to Trichodesmium’s ecological success and global biogeochemical impact, and may contribute to the leaching of particulate trace metals with implications for global iron and carbon cycling.

scholarly journals Effect of 8-Day Fasting on Leukocytes Expression of Genes and Proteins Involved in Iron Metabolism in Healthy Men

2021 ◽  
Vol 22 (6) ◽  
pp. 3248
Author(s):  
Andżelika Borkowska ◽  
Maja Tomczyk ◽  
Małgorzata Żychowska ◽  
Wiesław Pilis ◽  
Michał Zych ◽  
...  
Keyword(s):  
Exercise Capacity ◽  
Molecular Mechanisms ◽  
Iron Acquisition ◽  
Quantitative Polymerase Chain Reaction ◽  
Essential Element ◽  
The Body ◽  
Iron Storage ◽  
Healthy Men ◽  
Protein Levels ◽  
Expression Of Genes

The popularity of fasting and restricted food intake is increasing. While the body’s adaptability to dietary insufficiency is crucial for health, molecular mechanisms of adaptive changes are not well understood. Here, we compared the effects of fasting and exercise on the expression of leukocyte genes and proteins involved in the storage, export, and acquisition of iron, an essential element with physiological roles. Healthy men participated in the study (age, 30–70 years; body weight, 60–100 kg; body mass index, 20–29.9 kg/m2). The participants performed an exercise test with a gradually increasing intensity until the individual maximum exercise capacity was reached, before and after 8-d fast. Blood samples were collected before, immediately after, and 3 h after exercise. Gene expression was analyzed by reverse-transcription quantitative polymerase chain reaction and protein levels were analyzed by immunobloting. Eight days of total starvation diet affected the body composition and decreased exercise capacity. Further, fasting decreased the expression of genes associated with iron storage and export, and increased the expression of genes involved in iron acquisition. Conversely, only PCBP2 protein increased after fasting; however, an upward trend was apparent for all proteins. In conclusion, the body adapts to starvation by adjusting iron economy.

Polygonal profiles of ferritin molecules

1983 ◽  
Vol 41 ◽  
pp. 600-601
Author(s):  
William H. Massover
Keyword(s):  
Axial Ratio ◽  
X Ray Diffraction ◽  
Rhombic Dodecahedron ◽  
Apparent Contradiction ◽  
Iron Storage ◽  
X Ray ◽  
Hexagonal Shape ◽  
Axes Of Symmetry ◽  
Apparent Conflict ◽  
Iron Storage Protein

The molecular structure of the iron-storage protein, ferritin, is becoming known in ever finer detail. The 24 apoferritin subunits (MW ca. 20,000) have a 2:1 axial ratio and are polymerized with 4:3:2 symmetry to form an outer shell surrounding a variable amount of microcrystalline iron, Recent x-ray diffraction results indicate that the projected outline of the native molecule has a quasi-hexagonal shape when viewed down the 3-fold axes of symmetry, and a quasi-square shape when looking down the 4-fold axes. To date, no electron microscope study has reported observing anything other than circular profiles, which would indicate that ferritin is strictly spherical. The apparent conflict between the "hollow sphere" of electron microscopy (E.M.) and the "truncated rhombic dodecahedron" of x-ray diffraction could reflect the poorer effective resolution of E.M. coming from radiation damage, staining, drying, etc. The present study investigates the detailed shape of individual ferritin molecules in order to search for the predicted aspherical profiles and to interpret the nature of this apparent contradiction.

scholarly journals The Serratia marcescens Siderophore Serratiochelin Is Necessary for Full Virulence during Bloodstream Infection

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Danelle R. Weakland ◽  
Sara N. Smith ◽  
Bailey Bell ◽  
Ashootosh Tripathi ◽  
Harry L. T. Mobley
Keyword(s):  
Serratia Marcescens ◽  
Bloodstream Infection ◽  
Iron Acquisition ◽  
Gene Clusters ◽  
Clinical Isolates ◽  
Wild Type ◽  
Serratia Plymuthica ◽  
Content Type ◽  
Cas Assay ◽  
Essential Nutrient

ABSTRACT Serratia marcescens is a bacterium frequently found in the environment, but over the last several decades it has evolved into a concerning clinical pathogen, causing fatal bacteremia. To establish such infections, pathogens require specific nutrients; one very limited but essential nutrient is iron. We sought to characterize the iron acquisition systems in S. marcescens isolate UMH9, which was recovered from a clinical bloodstream infection. Using RNA sequencing (RNA-seq), we identified two predicted siderophore gene clusters (cbs and sch) that were regulated by iron. Mutants were constructed to delete each iron acquisition locus individually and in conjunction, generating both single and double mutants for the putative siderophore systems. Mutants lacking the sch gene cluster lost their iron-chelating ability as quantified by the chrome azurol S (CAS) assay, whereas the cbs mutant retained wild-type activity. Mass spectrometry-based analysis identified the chelating siderophore to be serratiochelin, a siderophore previously identified in Serratia plymuthica. Serratiochelin-producing mutants also displayed a decreased growth rate under iron-limited conditions created by dipyridyl added to LB medium. Additionally, mutants lacking serratiochelin were significantly outcompeted during cochallenge with wild-type UMH9 in the kidneys and spleen after inoculation via the tail vein in a bacteremia mouse model. This result was further confirmed by an independent challenge, suggesting that serratiochelin is required for full S. marcescens pathogenesis in the bloodstream. Nine other clinical isolates have at least 90% protein identity to the UMH9 serratiochelin system; therefore, our results are broadly applicable to emerging clinical isolates of S. marcescens causing bacteremia.

scholarly journals Localized cutaneous argyria: a new observation

2021 ◽  
Vol 12 (1) ◽  
pp. 30-32
Author(s):  
Selma El Kadiri ◽  
Hanane Baybay
Keyword(s):  
Cell Layer ◽  
Sweat Glands ◽  
Elastic Fibers ◽  
Dermatological Examination ◽  
Entire Duration ◽  
Nickel Copper ◽  
Iron Nickel ◽  
Superficial Dermis ◽  
Eccrine Sweat Glands ◽  
Switching Treatment

A 27-year-old female, a radiotherapy technician, was referred to our consultation with a localized gray pigmentation of the perinasal area. The condition had been asymptomatic for its entire duration of 2 years. A dermatological examination found a localized bluish-gray pigmentation in the perinasal area. Dermoscopy revealed an annular bluish-gray patch. Her occupation involved the manufacture and micromanipulation of machines, which required handling pure iron, nickel, copper, and silver with bare hands. She also reported a tic of flaring the nose. A skin biopsy was performed and histology revealed deposits of fine granules in the basal cell layer of eccrine sweat glands and along the elastic fibers of the superficial dermis, conforming with the diagnosis of argyria. The patient was given laser Q-switching treatment and showed a measurable improvement. This case studies a currently rare dermatological curiosity. Argyria is a disease caused by chronic absorption of silver-rich materials. This is the first description of argyria following the manipulation of radiopaque caches with a tic of flaring the nose.

scholarly journals PPE Surface Proteins Are Required for Heme Utilization by Mycobacterium tuberculosis

mBio ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Avishek Mitra ◽  
Alexander Speer ◽  
Kan Lin ◽  
Sabine Ehrt ◽  
Michael Niederweis
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Human Body ◽  
Iron Acquisition ◽  
Bacterial Pathogens ◽  
Surface Proteins ◽  
Resonance Spectroscopy ◽  
Heme Uptake ◽  
Human Host ◽  
Essential Nutrient ◽  
Growth Experiments

ABSTRACT Iron is essential for replication of Mycobacterium tuberculosis, but iron is efficiently sequestered in the human host during infection. Heme constitutes the largest iron reservoir in the human body and is utilized by many bacterial pathogens as an iron source. While heme acquisition is well studied in other bacterial pathogens, little is known in M. tuberculosis. To identify proteins involved in heme utilization by M. tuberculosis, a transposon mutant library was screened for resistance to the toxic heme analog gallium(III)-porphyrin (Ga-PIX). Inactivation of the ppe36, ppe62, and rv0265c genes resulted in resistance to Ga-PIX. Growth experiments using isogenic M. tuberculosis deletion mutants showed that PPE36 is essential for heme utilization by M. tuberculosis, while the functions of PPE62 and Rv0265c are partially redundant. None of the genes restored growth of the heterologous M. tuberculosis mutants, indicating that the proteins encoded by the genes have separate functions. PPE36, PPE62, and Rv0265c bind heme as shown by surface plasmon resonance spectroscopy and are associated with membranes. Both PPE36 and PPE62 proteins are cell surface accessible, while the Rv0265c protein is probably located in the periplasm. PPE36 and PPE62 are, to our knowledge, the first proline-proline-glutamate (PPE) proteins of M. tuberculosis that bind small molecules and are involved in nutrient acquisition. The absence of a virulence defect of the ppe36 deletion mutant indicates that the different iron acquisition pathways of M. tuberculosis may substitute for each other during growth and persistence in mice. The emerging model of heme utilization by M. tuberculosis as derived from this study is substantially different from those of other bacteria. IMPORTANCE Tuberculosis is caused by Mycobacterium tuberculosis and is a devastating disease affecting eight million people each year. Iron is an essential nutrient for replication of M. tuberculosis in the human host. More than 70% of iron in the human body is bound in heme. Not surprisingly, many bacterial pathogens, including M. tuberculosis, are able to acquire iron from heme. However, the mechanism of heme uptake by M. tuberculosis is poorly understood. We have identified two novel surface proteins that bind heme and are required for heme utilization by M. tuberculosis. These findings constitute a major advancement of our understanding of iron acquisition by M. tuberculosis and show that M. tuberculosis has evolved heme uptake systems different from the paradigms established by other bacteria. IMPORTANCE Tuberculosis is caused by Mycobacterium tuberculosis and is a devastating disease affecting eight million people each year. Iron is an essential nutrient for replication of M. tuberculosis in the human host. More than 70% of iron in the human body is bound in heme. Not surprisingly, many bacterial pathogens, including M. tuberculosis, are able to acquire iron from heme. However, the mechanism of heme uptake by M. tuberculosis is poorly understood. We have identified two novel surface proteins that bind heme and are required for heme utilization by M. tuberculosis. These findings constitute a major advancement of our understanding of iron acquisition by M. tuberculosis and show that M. tuberculosis has evolved heme uptake systems different from the paradigms established by other bacteria.

scholarly journals Transcriptomic Analysis of Staphylococcus xylosus in Solid Dairy Matrix Reveals an Aerobic Lifestyle Adapted to Rind

2020 ◽  
Vol 8 (11) ◽  
pp. 1807
Author(s):  
Sabine Leroy ◽  
Sergine Even ◽  
Pierre Micheau ◽  
Anne de La Foye ◽  
Valérie Laroute ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Antioxidant Enzymes ◽  
Dairy Products ◽  
Molecular Mechanisms ◽  
Iron Acquisition ◽  
Carbon Sources ◽  
Original System ◽  
Staphylococcus Xylosus ◽  
Genes Encoding

Staphylococcus xylosus is found in the microbiota of traditional cheeses, particularly in the rind of soft smeared cheeses. Despite its frequency, the molecular mechanisms allowing the growth and adaptation of S. xylosus in dairy products are still poorly understood. A transcriptomic approach was used to determine how the gene expression profile is modified during the fermentation step in a solid dairy matrix. S. xylosus developed an aerobic metabolism perfectly suited to the cheese rind. It overexpressed genes involved in the aerobic catabolism of two carbon sources in the dairy matrix, lactose and citrate. Interestingly, S. xylosus must cope with nutritional shortage such as amino acids, peptides, and nucleotides, consequently, an extensive up-regulation of genes involved in their biosynthesis was observed. As expected, the gene sigB was overexpressed in relation with general stress and entry into the stationary phase and several genes under its regulation, such as those involved in transport of anions, cations and in pigmentation were up-regulated. Up-regulation of genes encoding antioxidant enzymes and glycine betaine transport and synthesis systems showed that S. xylosus has to cope with oxidative and osmotic stresses. S. xylosus expressed an original system potentially involved in iron acquisition from lactoferrin.

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