The siderophore-mediated iron acquisition systems of Acinetobacter baumannii ATCC 19606 and Vibrio anguillarum 775 are structurally and functionally related

Microbiology ◽  
2004 ◽  
Vol 150 (11) ◽  
pp. 3657-3667 ◽  
Author(s):  
Caleb W. Dorsey ◽  
Andrew P. Tomaras ◽  
Pamela L. Connerly ◽  
Marcelo E. Tolmasky ◽  
Jorge H. Crosa ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Insertional Mutagenesis ◽  
Iron Acquisition ◽  
Vibrio Anguillarum ◽  
Structural Similarity ◽  
Iron Chelator ◽  
Transport Systems ◽  
Nucleotide Sequence Analysis ◽  
Bacterial Strains ◽  
Gene Encoding

The Acinetobacter baumannii type strain, ATCC 19606, secretes acinetobactin, a catechol siderophore highly related to the iron chelator anguibactin produced by the fish pathogen Vibrio anguillarum (Listonella anguillarum). This paper reports the initial characterization of the genes and gene products involved in the acinetobactin-mediated iron-acquisition process. Insertional mutagenesis resulted in the isolation of several derivatives whose ability to grow in medium containing the iron chelator 2,2′-dipyridyl was affected. One of the insertions disrupted a gene encoding a predicted outer-membrane protein, named BauA, highly similar to FatA, the receptor for ferric anguibactin. Immunological relatedness of BauA with FatA was confirmed by Western blot analysis. Another transposon insertion was mapped to a gene encoding a protein highly similar to FatD, the permease component of the anguibactin transport system. Further DNA sequencing and nucleotide sequence analysis revealed that these A. baumannii 19606 genes are part of a polycistronic locus that contains the bauDCEBA ORFs. While the translation products of bauD, -C, -B and -A are highly related to the V. anguillarum FatDCBA iron-transport proteins, the product of bauE is related to the ATPase component of Gram-positive ATP-binding cassette (ABC) transport systems. This entire locus is flanked by genes encoding predicted proteins related to AngU and AngN, V. anguillarum proteins required for the biosynthesis of anguibactin. These protein similarities, as well as the structural similarity of anguibactin and acinetobactin, suggested that these two siderophores could be utilized by both bacterial strains, a possibility that was confirmed by siderophore utilization bioassays. Taken together, these results demonstrate that these pathogens, which cause serious infections in unrelated hosts, express very similar siderophore-mediated iron-acquisition systems.

scholarly journals Isolation and Characterization of FecA- and FeoB-Mediated Iron Acquisition Systems of the Spirochete Leptospira biflexa by Random Insertional Mutagenesis

2005 ◽  
Vol 187 (9) ◽  
pp. 3249-3254 ◽  
Author(s):  
Hélène Louvel ◽  
Isabelle Saint Girons ◽  
Mathieu Picardeau
Keyword(s):  
Insertional Mutagenesis ◽  
Iron Acquisition ◽  
Transposon Mutagenesis ◽  
Ecological Niches ◽  
Acid Biosynthesis ◽  
Gene Encoding ◽  
Isolation And Characterization ◽  
Transposon Mutants

ABSTRACT The specific mechanisms by which Leptospira spp. acquire iron from their ecological niches are unknown. A major factor contributing to our ignorance of spirochetal biology is the lack of methods for genetic analysis of these organisms. In this study, we have developed a system for random transposon mutagenesis of Leptospira biflexa using a mariner transposon, Himar1. To demonstrate the validity of Himar1 in vivo transposon mutagenesis in L. biflexa, a screen of mutants for clones impaired in amino acid biosynthesis was first performed, enabling the identification of tryptophan and glutamate auxotrophs. To investigate iron transporters, 2,000 L. biflexa transposon mutants were screened onto media with and without hemin, thus allowing the identification of five hemin-requiring mutants, and the putative genes responsible for this phenotype were identified. Three mutants had distinct insertions in a gene encoding a protein which shares homology with the TonB-dependent receptor FecA, involved in ferric citrate transport. We also identified two mutants with a Himar1 insertion into a feoB-like gene, the product of which is required for ferrous iron uptake in many bacterial organisms. Interestingly, the growth inhibition exhibited by the fecA and feoB mutants was relieved by deferoxamine, suggesting the presence of a ferric hydroxamate transporter. These results confirm the importance of iron for the growth of Leptospira and its ability to use multiple iron sources.

scholarly journals A hag Mutant of Moraxella catarrhalis Strain O35E Is Deficient in Hemagglutination, Autoagglutination, and Immunoglobulin D-Binding Activities

2002 ◽  
Vol 70 (8) ◽  
pp. 4523-4533 ◽  
Author(s):  
Melanie M. Pearson ◽  
Eric R. Lafontaine ◽  
Nikki J. Wagner ◽  
Joseph W. St. Geme ◽  
Eric J. Hansen
Keyword(s):  
Moraxella Catarrhalis ◽  
Insertional Mutagenesis ◽  
Human Erythrocytes ◽  
Nucleotide Sequence Analysis ◽  
Dense Layer ◽  
Wild Type ◽  
Triple Mutant ◽  
Gene Encoding ◽  
Transmission Electron ◽  
Immunoglobulin D

ABSTRACT Previous studies correlated the presence of a 200-kDa protein on the surface of Moraxella catarrhalis with the ability of this organism to agglutinate human erythrocytes (M. Fitzgerald, R. Mulcahy, S. Murphy, C. Keane, D. Coakley, and T. Scott, FEMS Immunol. Med. Microbiol. 18:209-216, 1997). In the present study, the gene encoding the 200-kDa protein (designated Hag) of M. catarrhalis strain O35E was subjected to nucleotide sequence analysis and then was inactivated by insertional mutagenesis. The isogenic hag mutant was unable to agglutinate human erythrocytes and lost its ability to autoagglutinate but was still attached at wild-type levels to several human epithelial cell lines. The hag mutation also eliminated the ability of this mutant strain to bind human immunoglobulin D. The presence of the Hag protein on the M. catarrhalis cell surface, as well as that of the UspA1 and UspA2 proteins (C. Aebi, I. Maciver, J. L. Latimer, L. D. Cope, M. K. Stevens, S. E. Thomas, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 65:4367-4377, 1997), was investigated by transmission electron and cryoimmunoelectron microscopy. Wild-type M. catarrhalis strain O35E possessed a dense layer of surface projections, whereas an isogenic uspA1 uspA2 hag triple mutant version of this strain did not possess any detectable surface projections. Examination of a uspA1 uspA2 double mutant that expressed the Hag protein revealed the presence of a relatively sparse layer of surface projections, similar to those seen on a uspA2 hag mutant that expressed UspA1. In contrast, a uspA1 hag mutant that expressed UspA2 formed a very dense layer of relatively short surface projections. These results indicate that the surface-exposed Hag protein and UspA1 and UspA2 have the potential to interact both with each other and directly with host defense systems.

scholarly journals Cloning and nucleotide sequence analysis of a gene encoding an OXA-derived beta-lactamase in Acinetobacter baumannii.

1997 ◽  
Vol 41 (12) ◽  
pp. 2757-2759 ◽  
Author(s):  
J Vila ◽  
M Navia ◽  
J Ruiz ◽  
C Casals
Keyword(s):  
Sequence Analysis ◽  
Nucleotide Sequence ◽  
Acinetobacter Baumannii ◽  
Clinical Strain ◽  
Nucleotide Sequence Analysis ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Gene Encoding ◽  
Beta Lactamases ◽  
Beta Lactam Antibiotics

A clinical strain of Acinetobacter baumannii (strain Ab41) that was resistant to all beta-lactam antibiotics tested except ceftazidime, ceftriaxone, ceftizoxime, and imipenem produced three beta-lactamases: a presumptive chromosomal cephalosporinase, a TEM-1-like beta-lactamase (pI 5.4), and a novel OXA-derived beta-lactamase named OXA-21 (pI 7.0). The gene encoding OXA-21 was located in an integron. The nucleotide sequence showed three mutations compared with the sequence of OXA-3, with two being silent; the nonsilent mutation generated a substitution of Ile-217 to Met.

scholarly journals Discrimination of hospital isolates of Acinetobacter baumannii using repeated sequences and whole genome alignment differential analysis

2021 ◽  
Author(s):  
Roman Kotłowski ◽  
Alicja Nowak-Zaleska ◽  
Grzegorz Węgrzyn
Keyword(s):  
Acinetobacter Baumannii ◽  
Time Frame ◽  
Repeated Sequences ◽  
Hospital Environment ◽  
Genome Alignment ◽  
Whole Genome ◽  
Differential Analysis ◽  
Gene Encoding ◽  
Resistance Patterns ◽  
Whole Genome Alignment

AbstractAn optimized method for bacterial strain differentiation, based on combination of Repeated Sequences and Whole Genome Alignment Differential Analysis (RS&WGADA), is presented in this report. In this analysis, 51 Acinetobacter baumannii multidrug-resistance strains from one hospital environment and patients from 14 hospital wards were classified on the basis of polymorphisms of repeated sequences located in CRISPR region, variation in the gene encoding the EmrA-homologue of E. coli, and antibiotic resistance patterns, in combination with three newly identified polymorphic regions in the genomes of A. baumannii clinical isolates. Differential analysis of two similarity matrices between different genotypes and resistance patterns allowed to distinguish three significant correlations (p < 0.05) between 172 bp DNA insertion combined with resistance to chloramphenicol and gentamycin. Interestingly, 45 and 55 bp DNA insertions within the CRISPR region were identified, and combined during analyses with resistance/susceptibility to trimethoprim/sulfamethoxazole. Moreover, 184 or 1374 bp DNA length polymorphisms in the genomic region located upstream of the GTP cyclohydrolase I gene, associated mainly with imipenem susceptibility, was identified. In addition, considerable nucleotide polymorphism of the gene encoding the gamma/tau subunit of DNA polymerase III, an enzyme crucial for bacterial DNA replication, was discovered. The differentiation analysis performed using the above described approach allowed us to monitor the distribution of A. baumannii isolates in different wards of the hospital in the time frame of several years, indicating that the optimized method may be useful in hospital epidemiological studies, particularly in identification of the source of primary infections.

Molecular cloning and nucleotide sequence analysis of the gene encoding the immunoreactive Brucella abortus Hsp60 protein, BA60K

1992 ◽  
Vol 12 (1) ◽  
pp. 47-62 ◽  
Author(s):  
R.Martin Roop ◽  
Michelle L. Price ◽  
Bruce E. Dunn ◽  
Stephen M. Boyle ◽  
Nammalwar Sriranganathan ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Nucleotide Sequence ◽  
Molecular Cloning ◽  
Brucella Abortus ◽  
Nucleotide Sequence Analysis ◽  
Gene Encoding ◽  
Hsp60 Protein

MICROBIOLOGICAL PROFILE, ANTIBIOTIC SENSITIVITY AND PROGNOSIS OF PATIENTS WITH FOURNIER’S GANGRENE: A PROSPECTIVE, HOSPITAL BASED STUDY FROM NORTH INDIA

2021 ◽  
pp. 78-80
Author(s):  
Sanjay Gupta ◽  
Ajay Kumar ◽  
Adiveeth Deb
Keyword(s):  
Mortality Rate ◽  
Acinetobacter Baumannii ◽  
Ventilatory Support ◽  
Antibiotic Sensitivity ◽  
Fournier’S Gangrene ◽  
North India ◽  
Klebsiella Pneumonia ◽  
Bacterial Strains ◽  
Perianal Region ◽  
Fournier's Gangrene

Background: Fournier's gangrene (FG) is a devastating disease that is characterized by necrotizing fasciitis of the perineal, genital, or perianal region. Broad-spectrum antibiotics are the key component of its treatment. However, there is paucity of data regarding the optimal empirical antibiotic therapy for FG. Materials and Methods: Data from patients who underwent surgery for FG was retrieved from a prospectively collected departmental FG database. Demographics, clinical characteristics, causative pathogens and drug susceptibility/resistance were evaluated. Outcome was also assessed in terms of mortality. Results: Fifty patients with a median age of 58.5 (40-83) years were included. The perianal region and scrotum (88%) were the most commonly affected. Diabetes mellitus (DM) was the most common comorbidity (92%). The median time to onset of symptoms was 7 (2-15) days, and the median duration of hospital stay was 22 (4-65) days. Ventilator requirement was required in 15 (30%) patients. The median UFGSI score was 9.5 (3-15). The overall mortality rate was 26%. A positive growth was found in specimen cultures of 48 (96%) patients. The median number of bacterial strains that grew in the cultures was 3 (0-10). Amikacin was the antibiotic with the highest frequency of sensitivity (74%), while the highest resistance was observed against ampicillin-sulbactam (64%). Escherichia coli was the most common microorganism (68%). Acinetobacter baumannii and Klebsiella pneumonia were signicantly more common in patients who required mechanical ventilation. The mortality rate was 26%. An Uludag Fournier's Gangrene Severity Index (UFGSI) score of > 9.5 and ventilatory support requirement were factors associated with an increased rate of mortality. Acinetobacter baumannii was the only microorganism which was associated with an increased mortality rate. Conclusion: Causative pathogens in FG appeared to be shifting; thus, empirical antibiotic treatment for this disease should be modied. We recommend 3rd-generation cephalosporin, metronidazole and amikacin for empirical therapy.

scholarly journals Acid-Inducible Transcription of the Operon Encoding the Citrate Lyase Complex of Lactococcus lactis Biovar diacetylactis CRL264

2004 ◽  
Vol 186 (17) ◽  
pp. 5649-5660 ◽  
Author(s):  
Mauricio G. Martín ◽  
Pablo D. Sender ◽  
Salvador Peirú ◽  
Diego de Mendoza ◽  
Christian Magni
Keyword(s):  
Lactococcus Lactis ◽  
Acid Stress ◽  
Nucleotide Sequence Analysis ◽  
Transcriptional Level ◽  
Chromosomal Dna ◽  
Gene Encoding ◽  
Reading Frame ◽  
Polycistronic Mrna ◽  
Citrate Transporter ◽  
Citrate Lyase

ABSTRACT Although Lactococcus is one of the most extensively studied lactic acid bacteria and is the paradigm for biochemical studies of citrate metabolism, little information is available on the regulation of the citrate lyase complex. In order to fill this gap, we characterized the genes encoding the subunits of the citrate lyase of Lactococcus lactis CRL264, which are located on an 11.4-kb chromosomal DNA region. Nucleotide sequence analysis revealed a cluster of eight genes in a new type of genetic organization. The citM-citCDEFXG operon (cit operon) is transcribed as a single polycistronic mRNA of 8.6 kb. This operon carries a gene encoding a malic enzyme (CitM, a putative oxaloacetate decarboxylase), the structural genes coding for the citrate lyase subunits (citD, citE, and citF), and the accessory genes required for the synthesis of an active citrate lyase complex (citC, citX, and citG). We have found that the cit operon is induced by natural acidification of the medium during cell growth or by a shift to media buffered at acidic pHs. Between the citM and citC genes is a divergent open reading frame whose expression was also increased at acidic pH, which was designated citI. This inducible response to acid stress takes place at the transcriptional level and correlates with increased activity of citrate lyase. It is suggested that coordinated induction of the citrate transporter, CitP, and citrate lyase by acid stress provides a mechanism to make the cells (more) resistant to the inhibitory effects of the fermentation product (lactate) that accumulates under these conditions.

scholarly journals Comparison between Pseudomonas aeruginosa siderophores and desferrioxamine for iron acquisition from ferritin

2010 ◽  
Vol 4 (4) ◽  
pp. 631-635 ◽  
Author(s):  
Somporn Srifuengfung ◽  
Susan Assanasen ◽  
Malulee Tuntawiroon ◽  
Sumonrat Meejanpetch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Iron Acquisition ◽  
Iron Chelator ◽  
Dialysis Membrane ◽  
In Vitro Experiment ◽  
Iron Mobilization ◽  
Ph Values ◽  
Minimum Medium ◽  
Stimulation Of

Abstract Background: Siderophore is an iron chelator produced by microorganism. Pseudomonas aeruginosa produces two siderophores (pyoverdin and pyochelin). Desferrioxamine is a siderophore used in thalassemia patients to treat an iron overload of vital organs. Objective: Compare the ability of pyoverdin, pyochelin, and desferrioxamine for iron mobilization from ferritin. Materials and Methods: In vitro experiment, the ability of P. aeruginosa siderophores and desferrioxamine for iron mobilization from ferritin was compared by using a dialysis membrane assay at pH values of 7.4 and 6.0. Stimulation of P. aeruginosa PAO1 growth by all siderophores was studied in glucose minimum medium. Results: All three compounds were capable of iron mobilization at both pHs. At pH 6.0, the most effectiveness compound was desferrioxamine (31.6%), followed by pyoverdin (21.5%) and pyochelin (13.7%) compared on weight basis, each at 10 μg/mL. At equimolar concentration, their activities were desferrioxamine (38.5±1.2%), followed by pyoverdin (32.0±4.8%) and pyochelin (26.7±1.9%), respectively. Conclusion: The most effective compound in iron mobilization from ferritin was desferrioxamine, followed by pyoverdin and pyochelin respectively.

The Corynebacterium diphtheriae HbpA hemoglobin-binding protein contains a domain that is critical for hemoprotein-binding, cellular localization and function.

2021 ◽  
Author(s):  
Lindsey R. Lyman ◽  
Eric D. Peng ◽  
Michael P. Schmitt
Keyword(s):  
Cellular Localization ◽  
Binding Protein ◽  
Protein Localization ◽  
Iron Acquisition ◽  
Corynebacterium Diphtheriae ◽  
Terminal Region ◽  
Surface Proteins ◽  
Size Exclusion ◽  
Transport Systems ◽  
Iron Source

The acquisition of hemin-iron from hemoglobin-haptoglobin (Hb-Hp) by Corynebacterium diphtheriae requires the iron-regulated surface proteins HtaA, ChtA, ChtC, and the recently identified Hb-Hp binding protein HbpA. We previously showed that a purified form of HbpA (HbpA-S), lacking the C-terminal region, was able to bind Hb-Hp. In this study, we show that the C-terminal region of HbpA significantly enhances binding to Hb-Hp. A purified form of HbpA that includes the C-terminal domain (HbpA-FL) exhibits much stronger binding to Hb-Hp than HbpA-S. Size exclusion chromatography (SEC) showed that HbpA-FL as well as HtaA-FL, ChtA-FL, and ChtC-FL exist as high molecular weight complexes, while HbpA-S is present as a monomer, indicating that the C-terminal region is required for formation of large aggregates. Growth studies showed that expression of HbpA-FL in the Δ hbpA mutant restored wild-type levels of growth in low-iron medium that contained Hb-Hp as the sole iron source, while HbpA-S failed to complement the Δ hbpA mutant. Protein localization studies in C. diphtheriae showed that HbpA-FL is present in both in the supernatant and in the membrane fractions, and that the C-terminal region is required for membrane anchoring. Purified HbpA-FL was able to enhance growth of the Δ hbpA mutant when added to culture medium that contained Hb-Hp as a sole iron source, suggesting that secreted HbpA is involved in the use of hemin-iron from Hb-Hp. These studies extend our understanding of this novel Hb-Hp binding protein in this important human pathogen. IMPORTANCE Hemoproteins, such as Hb, are an abundant source of iron in humans and are proposed to be required by numerous pathogens to cause disease. In this report, we expand on our previous studies in further defining the role of HbpA in hemin-iron acquisition in C. diphtheriae . HbpA is unique to C. diphtheriae , and appears to function unlike any previously described bacterial iron-regulated Hb- or Hb-Hp-binding protein. HbpA is both secreted and present in the membrane, and exists as a large aggregate that enhances its ability to bind Hb-Hp and promote hemin-iron uptake. Current studies with HbpA will increase our understanding of iron transport systems in C. diphtheriae .

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