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Zlatkov N, Gunnari W, Resch U. Comparative label-free proteomics of the neonatal meningitis-causing Escherichia coli K1 IHE3034 and RS218 morphotypes. Microbiol Resour Announc 2024; 13:e0096023. [PMID: 38289054 PMCID: PMC10868230 DOI: 10.1128/mra.00960-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/22/2023] [Indexed: 02/16/2024] Open
Abstract
The proteome of two newborn meningitis Escherichia coli K1 (NMEC) morphotypes was examined via a label-free proteomics approach. Besides shared NMEC virulence factors, the two strains have different evolutionary strategies-strain IHE3034 tends to perform anaerobic respiration continuously, while strain RS218 maintains its filamentous morphotype due to active SOS response.
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Affiliation(s)
- Nikola Zlatkov
- Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Wilma Gunnari
- Department of Molecular Biology, Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Ulrike Resch
- Department of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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2
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Mushtaq F, Nadeem A, Yabrag A, Bala A, Karah N, Zlatkov N, Nyunt Wai S, Uhlin BE, Ahmad I. Colony phase variation switch modulates antimicrobial tolerance and biofilm formation in Acinetobacter baumannii. Microbiol Spectr 2024; 12:e0295623. [PMID: 38205963 PMCID: PMC10845969 DOI: 10.1128/spectrum.02956-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 12/09/2023] [Indexed: 01/12/2024] Open
Abstract
Carbapenem-resistant Acinetobacter baumannii causes one of the most difficult-to-treat nosocomial infections. Polycationic drugs like polymyxin B or colistin and tetracycline drugs such as doxycycline or minocycline are commonly used to treat infections caused by carbapenem-resistant A. baumannii. Here, we show that a subpopulation of cells associated with the opaque/translucent colony phase variation by A. baumannii AB5075 displays differential tolerance to subinhibitory concentrations of colistin and tetracycline. Using a variety of microscopic techniques, we demonstrate that extracellular polysaccharide moieties mediate colistin tolerance to opaque A. baumannii at single-cell level and that mushroom-shaped biofilm structures protect opaque bacteria at the community level. The colony switch phenotype is found to alter several traits of A. baumannii, including long-term survival under desiccation, tolerance to ethanol, competition with Escherichia coli, and intracellular survival in the environmental model host Acanthamoeba castellanii. Additionally, our findings suggest that extracellular DNA associated with membrane vesicles can promote colony switching in a DNA recombinase-dependent manner.IMPORTANCEAs a WHO top-priority drug-resistant microbe, Acinetobacter baumannii significantly contributes to hospital-associated infections worldwide. One particularly intriguing aspect is its ability to reversibly switch its colony morphotype on agar plates, which has been remarkably underexplored. In this study, we employed various microscopic techniques and phenotypic assays to investigate the colony phase variation switch under different clinically and environmentally relevant conditions. Our findings reveal that the presence of a poly N-acetylglucosamine-positive extracellular matrix layer contributes to the protection of bacteria from the bactericidal effects of colistin. Furthermore, we provide intriguing insights into the multicellular lifestyle of A. baumannii, specifically in the context of colony switch variation within its predatory host, Acanthamoeba castellanii.
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Affiliation(s)
- Fizza Mushtaq
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
| | - Aftab Nadeem
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Abdelbasset Yabrag
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Anju Bala
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Nabil Karah
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Irfan Ahmad
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden
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Ahmad I, Nadeem A, Mushtaq F, Zlatkov N, Shahzad M, Zavialov AV, Wai SN, Uhlin BE. Csu pili dependent biofilm formation and virulence of Acinetobacter baumannii. NPJ Biofilms Microbiomes 2023; 9:101. [PMID: 38097635 PMCID: PMC10721868 DOI: 10.1038/s41522-023-00465-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 11/23/2023] [Indexed: 12/17/2023] Open
Abstract
Acinetobacter baumannii has emerged as one of the most common extensive drug-resistant nosocomial bacterial pathogens. Not only can the bacteria survive in hospital settings for long periods, but they are also able to resist adverse conditions. However, underlying regulatory mechanisms that allow A. baumannii to cope with these conditions and mediate its virulence are poorly understood. Here, we show that bi-stable expression of the Csu pili, along with the production of poly-N-acetyl glucosamine, regulates the formation of Mountain-like biofilm-patches on glass surfaces to protect bacteria from the bactericidal effect of colistin. Csu pilus assembly is found to be an essential component of mature biofilms formed on glass surfaces and of pellicles. By using several microscopic techniques, we show that clinical isolates of A. baumannii carrying abundant Csu pili mediate adherence to epithelial cells. In addition, Csu pili suppressed surface-associated motility but enhanced colonization of bacteria into the lungs, spleen, and liver in a mouse model of systemic infection. The screening of c-di-GMP metabolizing protein mutants of A. baumannii 17978 for the capability to adhere to epithelial cells led us to identify GGDEF/EAL protein AIS_2337, here denoted PdeB, as a major regulator of Csu pili-mediated virulence and biofilm formation. Moreover, PdeB was found to be involved in the type IV pili-regulated robustness of surface-associated motility. Our findings suggest that the Csu pilus is not only a functional component of mature A. baumannii biofilms but also a major virulence factor promoting the initiation of disease progression by mediating bacterial adherence to epithelial cells.
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Affiliation(s)
- Irfan Ahmad
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187, Umeå, Sweden.
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan.
| | - Aftab Nadeem
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187, Umeå, Sweden
| | - Fizza Mushtaq
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187, Umeå, Sweden
- Institute of Biomedical and Allied Health Sciences, University of Health Sciences, Lahore, Pakistan
| | - Nikola Zlatkov
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187, Umeå, Sweden
| | - Muhammad Shahzad
- Department of Pharmacology, University of Health Sciences, Lahore, Pakistan
| | - Anton V Zavialov
- Department of Biochemistry, University of Turku, Tykistökatu 6A, 20520, Turku, Finland
| | - Sun Nyunt Wai
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, SE-90187, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology and Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187, Umeå, Sweden
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Nadeem A, Berg A, Pace H, Alam A, Toh E, Ådén J, Zlatkov N, Myint SL, Persson K, Gröbner G, Sjöstedt A, Bally M, Barandun J, Uhlin BE, Wai SN. Protein-lipid interaction at low pH induces oligomerization of the MakA cytotoxin from Vibrio cholerae. eLife 2022; 11:73439. [PMID: 35131030 PMCID: PMC8824476 DOI: 10.7554/elife.73439] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 01/19/2022] [Indexed: 12/29/2022] Open
Abstract
The α-pore-forming toxins (α-PFTs) from pathogenic bacteria damage host cell membranes by pore formation. We demonstrate a remarkable, hitherto unknown mechanism by an α-PFT protein from Vibrio cholerae. As part of the MakA/B/E tripartite toxin, MakA is involved in membrane pore formation similar to other α-PFTs. In contrast, MakA in isolation induces tube-like structures in acidic endosomal compartments of epithelial cells in vitro. The present study unravels the dynamics of tubular growth, which occurs in a pH-, lipid-, and concentration-dependent manner. Within acidified organelle lumens or when incubated with cells in acidic media, MakA forms oligomers and remodels membranes into high-curvature tubes leading to loss of membrane integrity. A 3.7 Å cryo-electron microscopy structure of MakA filaments reveals a unique protein-lipid superstructure. MakA forms a pinecone-like spiral with a central cavity and a thin annular lipid bilayer embedded between the MakA transmembrane helices in its active α-PFT conformation. Our study provides insights into a novel tubulation mechanism of an α-PFT protein and a new mode of action by a secreted bacterial toxin.
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Affiliation(s)
- Aftab Nadeem
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Alexandra Berg
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Science for Life Laboratory (SciLifeLab), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Hudson Pace
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Athar Alam
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Eric Toh
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Jörgen Ådén
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Si Lhyam Myint
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Karina Persson
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Gerhard Gröbner
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Chemistry, Umeå University, Umeå, Sweden
| | - Anders Sjöstedt
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Marta Bally
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden
| | - Jonas Barandun
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.,The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
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Myint SL, Zlatkov N, Aung KM, Toh E, Sjöström A, Nadeem A, Duperthuy M, Uhlin BE, Wai SN. Ecotin and LamB in Escherichia coli influence the susceptibility to Type VI secretion-mediated interbacterial competition and killing by Vibrio cholerae. Biochim Biophys Acta Gen Subj 2021; 1865:129912. [PMID: 33892013 DOI: 10.1016/j.bbagen.2021.129912] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND A prevailing action of the Type VI secretion system (T6SS) in several Gram-negative bacterial species is inter-bacterial competition. In the past several years, many effectors of T6SS were identified in different bacterial species and their involvement in inter-bacterial interactions were described. However, possible defence mechanisms against T6SS attack among prey bacteria were not well clarified yet. METHODS Escherichia coli was assessed for susceptibility to T6SS-mediated killing by Vibrio cholerae. TheT6SS-mediated bacterial killing assays were performed in absence or presence of different protease inhibitors and with different mutant E. coli strains. Expression levels of selected proteins were monitored using SDS-PAGE and immunoblot analyses. RESULTS The T6SS-mediated killing of E. coli by V. cholerae was partly blocked when the serine protease inhibitor Pefabloc was present. E. coli lacking the periplasmic protease inhibitor Ecotin showed enhanced susceptibility to killing by V. cholerae. Mutations affecting E. coli membrane stability also caused increased susceptibility to killing by V. cholerae. E. coli lacking the maltodextrin porin protein LamB showed reduced susceptibility to killing by V. cholerae whereas E. coli with induced high levels of LamB showed reduced survival in inter-bacterial competition. CONCLUSIONS Our study identified two proteins in E. coli, the intrinsic protease inhibitor Ecotin and the outer membrane porin LamB, that influenced E. coli susceptibility to T6SS-mediated killing by V. cholerae. GENERAL SIGNIFICANCE We envision that it is feasible to explore these findings to target and modulate their expression to obtain desired changes in inter-bacterial competition in vivo, e.g. in the gastrointestinal microbiome.
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Affiliation(s)
- Si Lhyam Myint
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Nikola Zlatkov
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Kyaw Min Aung
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Eric Toh
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Annika Sjöström
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Aftab Nadeem
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Marylise Duperthuy
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden; Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Succ. Centre-ville, Montréal, Québec, Canada.
| | - Bernt Eric Uhlin
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
| | - Sun Nyunt Wai
- Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden.
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Abstract
Bacterial membrane vesicles (BMVs) are spherical extracellular organelles whose cargo is enclosed by a biological membrane. The cargo can be delivered to distant parts of a given habitat in a protected and concentrated manner. This review presents current knowledge about BMVs in the context of bacterial eco-evolutionary dynamics among different environments and hosts. BMVs may play an important role in establishing and stabilizing bacterial communities in such environments; for example, bacterial populations may benefit from BMVs to delay the negative effect of certain evolutionary trade-offs that can result in deleterious phenotypes. BMVs can also perform ecosystem engineering by serving as detergents, mediators in biochemical cycles, components of different biofilms, substrates for cross-feeding, defense systems against different dangers and enzyme-delivery mechanisms that can change substrate availability. BMVs further contribute to bacteria as mediators in different interactions, with either other bacterial species or their hosts. In short, BMVs extend and deliver phenotypic traits that can have ecological and evolutionary value to both their producers and the ecosystem as a whole.
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Affiliation(s)
- Nikola Zlatkov
- Department of Molecular Biology and The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187 Umeå, Sweden
| | - Aftab Nadeem
- Department of Molecular Biology and The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187 Umeå, Sweden
| | - Bernt Eric Uhlin
- Department of Molecular Biology and The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187 Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology and The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, SE-90187 Umeå, Sweden
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Zlatkov N, Uhlin BE. Absence of Global Stress Regulation in Escherichia coli Promotes Pathoadaptation and Novel c-di-GMP-dependent Metabolic Capability. Sci Rep 2019; 9:2600. [PMID: 30796316 PMCID: PMC6385356 DOI: 10.1038/s41598-019-39580-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/25/2019] [Indexed: 01/17/2023] Open
Abstract
Pathoadaptive mutations linked to c-di-GMP signalling were investigated in neonatal meningitis-causing Escherichia coli (NMEC). The results indicated that NMEC strains deficient in RpoS (the global stress regulator) maintained remarkably low levels of c-di-GMP, a major bacterial sessility-motility switch. Deletion of ycgG2, shown here to encode a YcgG allozyme with c-di-GMP phosphodiesterase activity, and the restoration of RpoS led to a decrease in S-fimbriae, robustly produced in artificial urine, hinting that the urinary tract could serve as a habitat for NMEC. We showed that NMEC were skilled in aerobic citrate utilization in the presence of glucose, a property that normally does not exist in E. coli. Our data suggest that this metabolic novelty is a property of extraintestinal pathogenic E. coli since we reconstituted this ability in E. coli UTI89 (a cystitis isolate) via deactivation rpoS; additionally, a set of pyelonephritis E. coli isolates were shown here to aerobically use citrate in the presence of glucose. We found that the main reason for this metabolic capability is RpoS inactivation leading to the production of the citrate transporter CitT, exploited by NMEC for ferric citrate uptake dependent on YcgG2 (an allozyme with c-di-GMP phosphodiesterase activity).
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Affiliation(s)
- Nikola Zlatkov
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå University, Umea, Sweden
| | - Bernt Eric Uhlin
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå University, Umea, Sweden.
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Dimova LG, Zlatkov N, Verkade HJ, Uhlin BE, Tietge UJF. High-cholesterol diet does not alter gut microbiota composition in mice. Nutr Metab (Lond) 2017; 14:15. [PMID: 28239402 PMCID: PMC5314487 DOI: 10.1186/s12986-017-0170-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/05/2017] [Indexed: 02/07/2023] Open
Abstract
Introduction Western diet containing both saturated fat and cholesterol impairs cardio-metabolic health partly by modulating diversity and function of the microbiota. While diet containing only high fat has comparable effects, it is unclear how diets only enriched in cholesterol impact the microbiota. Therefore, we aimed to characterize the response of host and microbiota to a high cholesterol (HC) diet in mice susceptible to cardio-metabolic disease. Methods LDLR knockout mice received either 1.25% HC or no cholesterol containing control diet (NC) for 12 weeks before characterizing host cholesterol metabolism and intestinal microbiota composition (next generation sequencing). Results HC diet substantially increased plasma (1.6-fold) and liver cholesterol levels (21-fold), biliary cholesterol secretion (4.5-fold) and fecal neutral sterol excretion (68-fold, each p < 0.001) but not fecal bile acid excretion. Interestingly, despite the profound changes in intestinal cholesterol homeostasis no differences in microbial composition between control and HC-fed mice were detected. In both groups the main phyla were Bacteroidetes (55%), Firmicutes (27%) and Verrucomicrobia (14%). Conclusion Our results demonstrate that in mice HC diet alone does not alter the microbiota composition despite inducing substantial adaptive changes in whole body cholesterol homeostasis. The impact of Western diet on intestinal microbiota thus appears to be mediated exclusively by its high fat content. Electronic supplementary material The online version of this article (doi:10.1186/s12986-017-0170-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lidiya G Dimova
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Nikola Zlatkov
- Laboratory for Molecular Infection Medicine Sweden (MIMS) and Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Henkjan J Verkade
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Bernt Eric Uhlin
- Laboratory for Molecular Infection Medicine Sweden (MIMS) and Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Uwe J F Tietge
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Enow COA, Oscarsson J, Zlatkov N, Westermark M, Duperthuy M, Wai SN, Uhlin BE. Elevated recombinant clyA gene expression in the uropathogenic Escherichia coli strain 536, a clue to explain pathoadaptive mutations in a subset of extraintestinal E. coli strains. BMC Microbiol 2014; 14:216. [PMID: 25178918 PMCID: PMC4164713 DOI: 10.1186/s12866-014-0216-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 08/11/2014] [Indexed: 12/25/2022] Open
Abstract
Background Analysis of the Escherichia coli collection of reference strains (ECOR) for the presence of the gene locus clyA, which encodes the pore-forming protein ClyA (cytolysin A), revealed that a non-functional clyA locus is common among certain extraintestinal pathogenic E. coli (ExPEC). In fact, all 15 ECOR group B2 strains and several additionally examined extraintestinal pathogenic (uropathogenic (UPEC) and neonatal meningitis (NBM)) E. coli strains contained various ΔclyA alleles. Results There are at least four different variants of ΔclyA, suggesting that such deletions in clyA have arisen at more than one occasion. On the basis of this occurrence of the truncated clyA genes, we considered that there may be a patho-adaptive selection for deletions in clyA in extraintestinal pathogenic E. coli. In E. coli K-12 the clyA gene has been viewed as “cryptic” since it is tightly silenced by the nucleoid structuring protein H-NS. We constructed a restored clyA+ locus in derivatives of the UPEC strain 536 for further investigation of this hypothesis and, in particular, how the gene would be expressed. Our results show that the level of clyA+ expression is highly increased in the UPEC derivatives in comparison with the non-pathogenic E. coli K-12. Transcription of the clyA+ gene was induced to even higher levels when the SfaX regulatory protein was overproduced. The derivative with a restored clyA+ locus displayed a somewhat slower growth than the parental UPEC strain 536 when a sub-inhibitory concentration of the antimicrobial peptide Polymyxin B was added to the growth medium. Conclusions Taken together, our findings show that the clyA+ locus is expressed at an elevated level in the UPEC strain and we conclude that this is at least in part due to the effect of the SfaX/PapX transcriptional regulators. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0216-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | - Bernt Eric Uhlin
- Department of Molecular Biology, the Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, S-90187, Sweden.
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Dimitrova I, Balevska N, Petkov I, Iovev S, Zlatkov N, Durmisev A, Zvetanov Z. [Histopathological and histochemical studies in vitiligo following thalassotherapy]. Dermatol Monatsschr 1970; 156:1021-8. [PMID: 5508999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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