1
|
Vogt LN, Panis G, Schäpers A, Peschek N, Huber M, Papenfort K, Viollier PH, Fröhlich KS. Genome-wide profiling of Hfq-bound RNAs reveals the iron-responsive small RNA RusT in Caulobacter crescentus. mBio 2024; 15:e0315323. [PMID: 38511926 PMCID: PMC11005374 DOI: 10.1128/mbio.03153-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 02/28/2024] [Indexed: 03/22/2024] Open
Abstract
The alphaproteobacterium Caulobacter crescentus thrives in oligotrophic environments and is able to optimally exploit minimal resources by entertaining an intricate network of gene expression control mechanisms. Numerous transcriptional activators and repressors have been reported to contribute to these processes, but only few studies have focused on regulation at the post-transcriptional level in C. crescentus. Small RNAs (sRNAs) are a prominent class of regulators of bacterial gene expression, and most sRNAs characterized today engage in direct base-pairing interactions to modulate the translation and/or stability of target mRNAs. In many cases, the ubiquitous RNA chaperone, Hfq, contributes to the establishment of RNA-RNA interactions. Although the deletion of the hfq gene is associated with a severe loss of fitness in C. crescentus, the RNA ligands of the chaperone have remained largely unexplored. Here we report on the identification of coding and non-coding transcripts associated with Hfq in C. crescentus and demonstrate Hfq-dependent post-transcriptional regulation in this organism. We show that the Hfq-bound sRNA RusT is transcriptionally controlled by the NtrYX two-component system and induced in response to iron starvation. By combining RusT pulse expression with whole-genome transcriptome analysis, we determine 16 candidate target transcripts that are deregulated, many of which encode outer membrane transporters. We hence suggest RusT to support remodeling of the C. crescentus cell surface when iron supplies are limited.IMPORTANCEThe conserved RNA-binding protein Hfq contributes significantly to the adaptation of bacteria to different environmental conditions. Hfq not only stabilizes associated sRNAs but also promotes inter-molecular base-pairing interactions with target transcripts. Hfq plays a pivotal role for growth and survival, controlling central metabolism and cell wall synthesis in the oligotroph Caulobacter crescentus. However, direct evidence for Hfq-dependent post-transcriptional regulation and potential oligotrophy in C. crescentus has been lacking. Here, we identified sRNAs and mRNAs associated with Hfq in vivo, and demonstrated the requirement of Hfq for sRNA-mediated regulation, particularly of outer membrane transporters in C. crescentus.
Collapse
Affiliation(s)
- Laura N. Vogt
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Anna Schäpers
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Nikolai Peschek
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Michaela Huber
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Kai Papenfort
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University, Jena, Germany
| | - Patrick H. Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Kathrin S. Fröhlich
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
- Department of Biology I, Microbiology, Ludwig-Maximilians-University Munich, Munich, Germany
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University, Jena, Germany
| |
Collapse
|
2
|
Southwell JW, Black CM, Duhme-Klair AK. Experimental Methods for Evaluating the Bacterial Uptake of Trojan Horse Antibacterials. ChemMedChem 2020; 16:1063-1076. [PMID: 33238066 DOI: 10.1002/cmdc.202000806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Indexed: 01/10/2023]
Abstract
The field of antibacterial siderophore conjugates, referred to as Trojan Horse antibacterials, has received increasing attention in recent years, driven by the rise of antimicrobial resistance. Trojan Horse antibacterials offer an opportunity to exploit the specific pathways present in bacteria for active iron uptake, potentially allowing the drugs to bypass membrane-associated resistance mechanisms. Hence, the Trojan Horse approach might enable the redesigning of old antibiotics and the development of antibacterials that target specific pathogens. Critical parts of evaluating such Trojan Horse antibacterials and improving their design are the quantification of their bacterial uptake and the identification of the pathways by which this occurs. In this minireview, we highlight a selection of the biological and chemical methods used to study the uptake of Trojan Horse antibacterials, exemplified with case studies, some of which have led to drug candidates in clinical development or approved antibiotics.
Collapse
Affiliation(s)
- James W Southwell
- Department of Chemistry, University of York, Heslington, North Yorkshire, YO10 5DD, UK
| | - Conor M Black
- Department of Chemistry, University of York, Heslington, North Yorkshire, YO10 5DD, UK
| | | |
Collapse
|
3
|
Khan A, Singh P, Srivastava A. Iron: Key player in cancer and cell cycle? J Trace Elem Med Biol 2020; 62:126582. [PMID: 32673942 DOI: 10.1016/j.jtemb.2020.126582] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 12/31/2019] [Accepted: 06/09/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND Iron is an essential element for growth and metabolic activities of all living organisms but remains in its oxyhydroxide ferric ion form in the surrounding. Unavailability of iron in soluble ferrous form led to development of specific pathways and machinery in different organisms to make it available for use and maintain its homeostasis. Iron homeostasis is essential as under different circumstances iron in excess as well as deprivation leads to different pathological conditions in human. OBJECTIVE This review highlights the current findings related to iron excess as well as deprivation with regards to cellular proliferation. CONCLUSIONS Iron excess is extensively associated with different types of cancers viz. colorectal cancer, breast cancer etc. by producing an oxidative stressed condition and alteration of immune system. Ironically its deprivation also results in anaemic conditions and leads to cell cycle arrest at different phases with mechanism yet to be explored. Iron deprivation arrests cell cycle at G1/S and in some cases at G2/M checkpoints resulting in growth arrest. However, in some cases iron overload arrests cell cycle at G1 phase by blocking certain signalling pathways. Certain natural and synthetic iron chelators are being explored from few decades to combat diseases caused by alteration in iron homeostasis.
Collapse
Affiliation(s)
- Azmi Khan
- Department of Life Science, School of Earth, Biological and Environmental Sciences, Central University of South Bihar, Gaya, Bihar, India
| | - Pratika Singh
- Department of Life Science, School of Earth, Biological and Environmental Sciences, Central University of South Bihar, Gaya, Bihar, India
| | - Amrita Srivastava
- Department of Life Science, School of Earth, Biological and Environmental Sciences, Central University of South Bihar, Gaya, Bihar, India.
| |
Collapse
|
4
|
Tamuhla T, Joubert L, Willemse D, Williams MJ. SufT is required for growth of Mycobacterium smegmatis under iron limiting conditions. MICROBIOLOGY-SGM 2020; 166:296-305. [PMID: 31860439 DOI: 10.1099/mic.0.000881] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Iron-sulphur (FeS) clusters are versatile cofactors required for a range of biological processes within cells. Due to the reactive nature of the constituent molecules, assembly and delivery of these cofactors requires a multi-protein machinery in vivo. In prokaryotes, SufT homologues are proposed to function in the maturation and transfer of FeS clusters to apo-proteins. This study used targeted gene deletion to investigate the role of SufT in the physiology of mycobacteria, using Mycobacterium smegmatis as a model organism. Deletion of the sufT gene in M. smegmatis had no impact on growth under standard culture conditions and did not significantly alter activity of the FeS cluster dependent enzymes succinate dehydrogenase (SDH) and aconitase (ACN). Furthermore, the ΔsufT mutant was no more sensitive than the wild-type strain to the redox cycler 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), or the anti-tuberculosis drugs isoniazid, clofazimine or rifampicin. In contrast, the ΔsufT mutant displayed a growth defect under iron limiting conditions, and an increased requirement for iron during biofilm formation. This data suggests that SufT is an accessory factor in FeS cluster biogenesis in mycobacteria which is required under conditions of iron limitation.
Collapse
Affiliation(s)
- Tsaone Tamuhla
- Present address: Department of Integrative Biomedical Sciences, Division of Computational Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Lydia Joubert
- Present address: Stanford-SLAC Cryo-EM Center, Stanford University, Stanford, USA.,Central Analytical Facilties, Microbiology Department, Stellenbosch University, Stellenbosch, South Africa
| | - Danicke Willemse
- Present address: Texas Biomedical Research Institute, 8715 West Military Drive, San Antonio, TX, USA.,DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Monique J Williams
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.,Present address: Department of Molecular and Cell Biology, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
5
|
Influence of Lactic Acid on Cell Cycle Progressions in Lactobacillus bulgaricus During Batch Culture. Appl Biochem Biotechnol 2020; 193:912-924. [PMID: 33206317 DOI: 10.1007/s12010-020-03459-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/08/2020] [Indexed: 02/02/2023]
Abstract
Lactic acid has been proved to inhibit the proliferation of lactic acid bacteria in the fermentation process. To shed light on the cell cycle alterations in acidic conditions, the cell division of Lactobacillus bulgaricus sp1.1 in batch culture was analyzed directly by implementing of the intracellular fluorescent tracking assay in different pH adjusted by lactic acid. Cell proliferation and cell division were investigated to be negatively controlled by the decrease of pH, and pH 4.1 was the critical condition of downregulating cell division but retains cell culturability. The cell area and cell length in pH 4.1 were examined by using fluorescent labeling, and they reduced to about 29.18-34.89% and 32.67-40% of cells cultured in the unacidified medium, respectively. The DNA replication initiation was undergoing prompted by the low extent of DNA condensation and higher expression of the dnaA gene in this critical pH. The results indicated that the cell cycle progressions of Lactobacillus bulgaricus sp1.1 in acidic conditions were arrested at intracellular biomass accumulation and cell division stage. These findings provide fundamental insight into cell cycle control of the acidic environment in Lactobacillus bulgaricus sp1.1.
Collapse
|
6
|
Henríquez T, Stein NV, Jung H. Resistance to Bipyridyls Mediated by the TtgABC Efflux System in Pseudomonas putida KT2440. Front Microbiol 2020; 11:1974. [PMID: 32973714 PMCID: PMC7461776 DOI: 10.3389/fmicb.2020.01974] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 07/27/2020] [Indexed: 01/26/2023] Open
Abstract
Resistance-nodulation-division (RND) transporters are involved in antibiotic resistance and have a broad substrate specificity. However, the physiological significance of these efflux pumps is not fully understood. Here, we have investigated the role of the RND system TtgABC in resistance to metal ion chelators in the soil bacterium Pseudomonas putida KT2440. We observed that the combined action of an RND inhibitor and the chelator 2,2'-bipyridyl inhibited bacterial growth. In addition, the deletion of ttgB made the strain susceptible to 2,2'-bipyridyl and natural bipyridyl derivatives such as caerulomycin A, indicating that TtgABC is required for detoxification of compounds of the bipyridyl family. Searching for the basis of growth inhibition by bipyridyls, we found reduced adenosine triphosphate (ATP) levels in the ttgB mutant compared to the wild type. Furthermore, the expression of genes related to iron acquisition and the synthesis of the siderophore pyoverdine were reduced in the mutant compared to the wild type. Investigating the possibility that 2,2'-bipyridyl in the ttgB mutant mediates iron accumulation in cells (which would cause the upregulation of genes involved in oxidative stress via the Fenton reaction), we measured the expression of genes coding for proteins involved in intracellular iron storage and the response to oxidative stress. However, none of the genes was significantly upregulated. In a further search for a possible link between 2,2'-bipyridyl and the observed phenotypes, we considered the possibility that the ion chelator limits the intracellular availability of metabolically important metal ions. In this context, we found that the addition of copper restores the growth of the ttgB mutant and the production of pyoverdine, suggesting a relationship between copper availability and iron acquisition. Taken together, the results suggest that detoxification of metal chelating compounds of the bipyridyl family produced by other bacteria or higher ordered organisms is one of the native functions of the RND efflux pump TtgABC. Without the efflux pump, these compounds may interfere with cell ion homeostasis with adverse effects on cell metabolism, including siderophore production. Finally, our results suggest that TtgABC is involved in resistance to bile salts and deoxycholate.
Collapse
Affiliation(s)
- Tania Henríquez
- Mikrobiologie, Biozentrum, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Heinrich Jung
- Mikrobiologie, Biozentrum, Ludwig-Maximilians-Universität München, Munich, Germany
| |
Collapse
|
7
|
Toro-Urrego N, Turner LF, Avila-Rodriguez MF. New Insights into Oxidative Damage and Iron Associated Impairment in Traumatic Brain Injury. Curr Pharm Des 2020; 25:4737-4746. [DOI: 10.2174/1381612825666191111153802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 10/28/2019] [Indexed: 12/14/2022]
Abstract
:
Traumatic Brain Injury is considered one of the most prevalent causes of death around the world; more
than seventy millions of individuals sustain the condition per year. The consequences of traumatic brain injury on
brain tissue are complex and multifactorial, hence, the current palliative treatments are limited to improve patients’
quality of life. The subsequent hemorrhage caused by trauma and the ongoing oxidative process generated
by biochemical disturbances in the in the brain tissue may increase iron levels and reactive oxygen species. The
relationship between oxidative damage and the traumatic brain injury is well known, for that reason, diminishing
factors that potentiate the production of reactive oxygen species have a promissory therapeutic use. Iron chelators
are molecules capable of scavenging the oxidative damage from the brain tissue and are currently in use for ironoverload-
derived diseases.
:
Here, we show an updated overview of the underlying mechanisms of the oxidative damage after traumatic brain
injury. Later, we introduced the potential use of iron chelators as neuroprotective compounds for traumatic brain
injury, highlighting the action mechanisms of iron chelators and their current clinical applications.
Collapse
Affiliation(s)
- Nicolas Toro-Urrego
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Instituto de Investigaciones Cardiológicas, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Liliana F. Turner
- Grupo Modelos Experimentales para las Ciencias Zoohumanas - Departamento de Biología Facultad de Ciencias, Universidad del Tolima- Ibagué, Tolima, Colombia
| | - Marco F. Avila-Rodriguez
- Grupo Modelos Experimentales para las Ciencias Zoohumanas - Departamento de Ciencias Clínicas- Facultad de Ciencias de la Salud, Universidad del Tolima- Ibagué, Tolima, Colombia
| |
Collapse
|
8
|
Ankley LM, Monteiro MP, Camp KM, O'Quinn R, Castillo AR. Manuka honey chelates iron and impacts iron regulation in key bacterial pathogens. J Appl Microbiol 2019; 128:1015-1024. [PMID: 31782867 DOI: 10.1111/jam.14534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 11/05/2019] [Accepted: 11/26/2019] [Indexed: 12/21/2022]
Abstract
AIM The aim of this study was to test the hypothesis that Manuka honey (MH) chelates iron and promotes an iron-limiting environment, which contributes to its antimicrobial activity. METHODS AND RESULTS Employing a ferrozine-based assay, we observed that MH is an iron chelator that depletes iron from solution. Siderophores are small molecules that bind ferric iron (III) with high affinity and their levels are upregulated by bacteria under iron-limiting conditions. We demonstrated by quantitating siderophore production that Escherichia coli and Pseudomonas aeruginosa treated with MH sub-minimum inhibitory concentrations (sub-MIC) experience an iron-limiting environment and increase siderophore production. In addition, supplementation with ferrous iron (II) significantly increased growth of E. coli, Staphylococcus aureus and P. aeruginosa cultured at their MH MIC above that observed in nonsupplemented controls. By contrast, supplementation with ferric iron (III) significantly increased growth for only E. coli and P. aeruginosa, above their nonsupplemented controls. CONCLUSIONS Manuka honey chelates iron, thereby generating an iron-limiting environment for E. coli and P. aeruginosa, and to a lesser extent S. aureus, which contributes to its antimicrobial properties. SIGNIFICANCE AND IMPACT OF THE STUDY Our work demonstrates that MH-induced iron chelation is an antimicrobial mechanism that differentially impacts the bacterial species tested here. Iron chelation affects multiple diverse physiological processes in bacteria and would contribute to the lack of bacterial resistance to MH. Iron metabolism is tightly regulated; bacteria require this essential nutrient for survival, but in excess it is toxic. Additional exploration of MH's iron chelation mechanism will facilitate its future use in mainstream medicine.
Collapse
Affiliation(s)
- L M Ankley
- Department of Biology, Eastern Washington University, Cheney, WA, USA
| | - M P Monteiro
- Department of Biology, Eastern Washington University, Cheney, WA, USA
| | - K M Camp
- Department of Biology, Eastern Washington University, Cheney, WA, USA
| | - R O'Quinn
- Department of Biology, Eastern Washington University, Cheney, WA, USA
| | - A R Castillo
- Department of Biology, Eastern Washington University, Cheney, WA, USA
| |
Collapse
|
9
|
Rivera GSM, Beamish CR, Wencewicz TA. Immobilized FhuD2 Siderophore-Binding Protein Enables Purification of Salmycin Sideromycins from Streptomyces violaceus DSM 8286. ACS Infect Dis 2018; 4:845-859. [PMID: 29460625 DOI: 10.1021/acsinfecdis.8b00015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Siderophores are a structurally diverse class of natural products common to most bacteria and fungi as iron(III)-chelating ligands. Siderophores, including trihydroxamate ferrioxamines, are used clinically to treat iron overload diseases and show promising activity against many other iron-related human diseases. Here, we present a new method for the isolation of ferrioxamine siderophores from complex mixtures using affinity chromatography based on resin-immobilized FhuD2, a siderophore-binding protein (SBP) from Staphylococcus aureus. The SBP-resin enabled purification of charge positive, charge negative, and neutral ferrioxamine siderophores. Treatment of culture supernatants from Streptomyces violaceus DSM 8286 with SBP-resin provided an analytically pure sample of the salmycins, a mixture of structurally complex glycosylated sideromycins (siderophore-antibiotic conjugates) with potent antibacterial activity toward human pathogenic Staphylococcus aureus (minimum inhibitory concentration (MIC) = 7 nM). Siderophore affinity chromatography could enable the rapid discovery of new siderophore and sideromycin natural products from complex mixtures to aid drug discovery and metabolite identification efforts in a broad range of therapeutic areas.
Collapse
Affiliation(s)
- Gerry Sann M. Rivera
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Catherine R. Beamish
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| |
Collapse
|