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Article ; Online: Isolation and Characterization of the Acinetobactin and Baumannoferrin Siderophores Produced by Acinetobacter baumannii.

Penwell, William F / Actis, Luis A

Methods in molecular biology (Clifton, N.J.)

2019 Volume 1946, Page(s) 259–270

Abstract: Siderophores are high-affinity iron chelators produced and used by bacteria to prosper under iron-limiting conditions they normally encounter in the environment and hosts. In this chapter, we describe the isolation and purification of the siderophores ... ...

Abstract	Siderophores are high-affinity iron chelators produced and used by bacteria to prosper under iron-limiting conditions they normally encounter in the environment and hosts. In this chapter, we describe the isolation and purification of the siderophores acinetobactin and baumannoferrin produced by the bacterial pathogen Acinetobacter baumannii using XAD-7 batch adsorption and high-pressure liquid chromatography (HPLC). We also describe chemical tests and biological assays used to detect the presence of catechol and hydroxamate siderophores in culture supernatants, XAD-7 extracts, and HPLC fractions.
MeSH term(s)	Acinetobacter baumannii/metabolism ; Catechols/chemistry ; Catechols/isolation & purification ; Chemistry Techniques, Analytical ; Chromatography ; Chromatography, High Pressure Liquid ; Imidazoles/chemistry ; Imidazoles/isolation & purification ; Imidazoles/metabolism ; Oxazoles/chemistry ; Oxazoles/isolation & purification ; Oxazoles/metabolism ; Siderophores/chemistry ; Siderophores/isolation & purification ; Siderophores/metabolism
Chemical Substances	Catechols ; Imidazoles ; Oxazoles ; Siderophores ; acinetobactin (160472-93-5) ; catechol (LF3AJ089DQ)
Language	English
Publishing date	2019-02-23
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
ISSN	1940-6029
ISSN (online)	1940-6029
DOI	10.1007/978-1-4939-9118-1_24
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Article ; Online: The Acinetobacter baumannii entA gene located outside the acinetobactin cluster is critical for siderophore production, iron acquisition and virulence.

Penwell, William F / Arivett, Brock A / Actis, Luis A

PloS one

2012 Volume 7, Issue 5, Page(s) e36493

Abstract: Acinetobacter baumannii causes severe infections in compromised patients, who present an iron-limited environment that controls bacterial growth. This pathogen has responded to this restriction by expressing high-affinity iron acquisition systems ... ...

Abstract	Acinetobacter baumannii causes severe infections in compromised patients, who present an iron-limited environment that controls bacterial growth. This pathogen has responded to this restriction by expressing high-affinity iron acquisition systems including that mediated by the siderophore acinetobactin. Gene cloning, functional assays and biochemical tests showed that the A. baumannii genome contains a single functional copy of an entA ortholog. This gene, which is essential for the biosynthesis of the acinetobactin precursor 2,3-dihydroxybenzoic acid (DHBA), locates outside of the acinetobactin gene cluster, which otherwise harbors all genes needed for acinetobactin biosynthesis, export and transport. In silico analyses and genetic complementation tests showed that entA locates next to an entB ortholog, which codes for a putative protein that contains the isochorismatase lyase domain, which is needed for DHBA biosynthesis from isochorismic acid, but lacks the aryl carrier protein domain, which is needed for tethering activated DHBA and completion of siderophore biosynthesis. Thus, basF, which locates within the acinetobactin gene cluster, is the only fully functional entB ortholog present in ATCC 19606(T). The differences in amino acid length and sequences between these two EntB orthologs and the differences in the genetic context within which the entA and entB genes are found in different A. baumannii isolates indicate that they were acquired from different sources by horizontal transfer. Interestingly, the AYE strain proved to be a natural entA mutant capable of acquiring iron via an uncharacterized siderophore-mediated system, an observation that underlines the ability of different A. baumannii isolates to acquire iron using different systems. Finally, experimental infections using in vivo and ex vivo models demonstrate the role of DHBA and acinetobactin intermediates in the virulence of the ATCC 19606(T) cells, although to a lesser extent when compared to the responses obtained with bacteria producing and using fully matured acinetobactin to acquire iron.
MeSH term(s)	Acinetobacter baumannii/genetics ; Acinetobacter baumannii/metabolism ; Acinetobacter baumannii/pathogenicity ; Chromosomes, Bacterial ; Cloning, Molecular ; Gene Order ; Genes, Bacterial ; Genetic Loci ; Imidazoles/metabolism ; Iron/metabolism ; Molecular Sequence Annotation ; Multigene Family ; Oxazoles/metabolism ; Phenotype ; Siderophores/biosynthesis ; Virulence/genetics
Chemical Substances	Imidazoles ; Oxazoles ; Siderophores ; acinetobactin (160472-93-5) ; Iron (E1UOL152H7)
Language	English
Publishing date	2012-05-03
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ISSN	1932-6203
ISSN (online)	1932-6203
DOI	10.1371/journal.pone.0036493
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Article: Identification of Potential Virulence Factors in the Model Strain

Ramirez, Maria S / Penwell, William F / Traglia, German M / Zimbler, Daniel L / Gaddy, Jennifer A / Nikolaidis, Nikolas / Arivett, Brock A / Adams, Mark D / Bonomo, Robert A / Actis, Luis A / Tolmasky, Marcelo E

Frontiers in microbiology

2019 Volume 10, Page(s) 1599

Abstract: Acinetobacter ... ...

Abstract	Acinetobacter baumannii
Language	English
Publishing date	2019-07-23
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2587354-4
ISSN	1664-302X
ISSN	1664-302X
DOI	10.3389/fmicb.2019.01599
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Article ; Online: The Acinetobacter baumannii entA gene located outside the acinetobactin cluster is critical for siderophore production, iron acquisition and virulence.

William F Penwell / Brock A Arivett / Luis A Actis

PLoS ONE, Vol 7, Iss 5, p e

2012 Volume 36493

Abstract	Acinetobacter baumannii causes severe infections in compromised patients, who present an iron-limited environment that controls bacterial growth. This pathogen has responded to this restriction by expressing high-affinity iron acquisition systems including that mediated by the siderophore acinetobactin. Gene cloning, functional assays and biochemical tests showed that the A. baumannii genome contains a single functional copy of an entA ortholog. This gene, which is essential for the biosynthesis of the acinetobactin precursor 2,3-dihydroxybenzoic acid (DHBA), locates outside of the acinetobactin gene cluster, which otherwise harbors all genes needed for acinetobactin biosynthesis, export and transport. In silico analyses and genetic complementation tests showed that entA locates next to an entB ortholog, which codes for a putative protein that contains the isochorismatase lyase domain, which is needed for DHBA biosynthesis from isochorismic acid, but lacks the aryl carrier protein domain, which is needed for tethering activated DHBA and completion of siderophore biosynthesis. Thus, basF, which locates within the acinetobactin gene cluster, is the only fully functional entB ortholog present in ATCC 19606(T). The differences in amino acid length and sequences between these two EntB orthologs and the differences in the genetic context within which the entA and entB genes are found in different A. baumannii isolates indicate that they were acquired from different sources by horizontal transfer. Interestingly, the AYE strain proved to be a natural entA mutant capable of acquiring iron via an uncharacterized siderophore-mediated system, an observation that underlines the ability of different A. baumannii isolates to acquire iron using different systems. Finally, experimental infections using in vivo and ex vivo models demonstrate the role of DHBA and acinetobactin intermediates in the virulence of the ATCC 19606(T) cells, although to a lesser extent when compared to the responses obtained with bacteria producing and ...
Keywords	Medicine ; R ; Science ; Q
Subject code	572
Language	English
Publishing date	2012-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
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Article ; Online: Antimicrobial Activity of Gallium Protoporphyrin IX against Acinetobacter baumannii Strains Displaying Different Antibiotic Resistance Phenotypes.

Arivett, Brock A / Fiester, Steven E / Ohneck, Emily J / Penwell, William F / Kaufman, Cynthia M / Relich, Ryan F / Actis, Luis A

Antimicrobial agents and chemotherapy

2015 Volume 59, Issue 12, Page(s) 7657–7665

Abstract: A paucity of effective, currently available antibiotics and a lull in antibiotic development pose significant challenges for treatment of patients with multidrug-resistant (MDR) Acinetobacter baumannii infections. Thus, novel therapeutic strategies must ... ...

Abstract	A paucity of effective, currently available antibiotics and a lull in antibiotic development pose significant challenges for treatment of patients with multidrug-resistant (MDR) Acinetobacter baumannii infections. Thus, novel therapeutic strategies must be evaluated to meet the demands of treatment of these often life-threatening infections. Accordingly, we examined the antibiotic activity of gallium protoporphyrin IX (Ga-PPIX) against a collection of A. baumannii strains, including nonmilitary and military strains and strains representing different clonal lineages and isolates classified as susceptible or MDR. Susceptibility testing demonstrated that Ga-PPIX inhibits the growth of all tested strains when cultured in cation-adjusted Mueller-Hinton broth, with a MIC of 20 μg/ml. This concentration significantly reduced bacterial viability, while 40 μg/ml killed all cells of the A. baumannii ATCC 19606(T) and ACICU MDR isolate after 24-h incubation. Recovery of ATCC 19606(T) and ACICU strains from infected A549 human alveolar epithelial monolayers was also decreased when the medium was supplemented with Ga-PPIX, particularly at a 40-μg/ml concentration. Similarly, the coinjection of bacteria with Ga-PPIX increased the survival of Galleria mellonella larvae infected with ATCC 19606(T) or ACICU. Ga-PPIX was cytotoxic only when monolayers or larvae were exposed to concentrations 16-fold and 1,250-fold higher than those showing antibacterial activity, respectively. These results indicate that Ga-PPIX could be a viable therapeutic option for treatment of recalcitrant A. baumannii infections regardless of the resistance phenotype, clone lineage, time and site of isolation of strains causing these infections and their iron uptake phenotypes or the iron content of the media.
MeSH term(s)	Acinetobacter Infections/drug therapy ; Acinetobacter Infections/microbiology ; Acinetobacter baumannii/drug effects ; Acinetobacter baumannii/growth & development ; Acinetobacter baumannii/metabolism ; Animals ; Anti-Bacterial Agents/chemistry ; Anti-Bacterial Agents/pharmacology ; Cell Line, Tumor ; Coordination Complexes/chemistry ; Coordination Complexes/pharmacology ; Drug Resistance, Multiple, Bacterial/drug effects ; Epithelial Cells/drug effects ; Epithelial Cells/microbiology ; Gallium/chemistry ; Gallium/pharmacology ; Humans ; Iron/metabolism ; Larva/drug effects ; Larva/microbiology ; Microbial Sensitivity Tests ; Microbial Viability/drug effects ; Moths/drug effects ; Moths/microbiology ; Phenotype ; Protoporphyrins/chemistry ; Protoporphyrins/pharmacology ; Survival Analysis
Chemical Substances	Anti-Bacterial Agents ; Coordination Complexes ; Protoporphyrins ; protoporphyrin IX (C2K325S808) ; Gallium (CH46OC8YV4) ; Iron (E1UOL152H7)
Language	English
Publishing date	2015-12
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	217602-6
ISSN	1098-6596 ; 0066-4804
ISSN (online)	1098-6596
ISSN	0066-4804
DOI	10.1128/AAC.01472-15
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Article ; Online: Discovery and Characterization of New Hydroxamate Siderophores, Baumannoferrin A and B, produced by Acinetobacter baumannii.

Penwell, William F / DeGrace, Nancy / Tentarelli, Sharon / Gauthier, Lise / Gilbert, Catherine M / Arivett, Brock A / Miller, Alita A / Durand-Reville, Thomas F / Joubran, Camil / Actis, Luis A

Chembiochem : a European journal of chemical biology

2015

Abstract: Acinetobacter baumannii AYE does not produce acinetobactin but grows under iron limitation. Accordingly, analyses of AYE iron-restricted culture supernatants resulted in the isolation of two fractions, which contained only hydroxamates and showed ... ...

Abstract	Acinetobacter baumannii AYE does not produce acinetobactin but grows under iron limitation. Accordingly, analyses of AYE iron-restricted culture supernatants resulted in the isolation of two fractions, which contained only hydroxamates and showed siderophore activity. Structural analyses identified baumannoferrin A and baumannoferrin B, which differ only by a double bond. These siderophores are composed of citrate, 1,3-diaminopropane, 2,4-diaminobutyrate, decenoic acid, and α-ketoglutarate. Analysis of the AYE genome showed the presence of a 12-gene cluster coding for proteins similar to those involved in the production and utilization of the hydroxamate siderophores acinetoferrin and achromobactin. As A. baumannii AYE does not produce acinetobactin and harbors only one gene cluster encoding the production and utilization of a siderophore, this strain's growth under iron limitation depends on baumannoferrin, a novel hydroxamate that could play a role in its virulence.
Language	English
Publishing date	2015-07-27
Publishing country	Germany
Document type	Journal Article
ZDB-ID	2020469-3
ISSN	1439-7633 ; 1439-4227
ISSN (online)	1439-7633
ISSN	1439-4227
DOI	10.1002/cbic.201500147
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Article ; Online: Molecular mechanisms of sulbactam antibacterial activity and resistance determinants in Acinetobacter baumannii.

Penwell, William F / Shapiro, Adam B / Giacobbe, Robert A / Gu, Rong-Fang / Gao, Ning / Thresher, Jason / McLaughlin, Robert E / Huband, Michael D / DeJonge, Boudewijn L M / Ehmann, David E / Miller, Alita A

Antimicrobial agents and chemotherapy

2015 Volume 59, Issue 3, Page(s) 1680–1689

Abstract: Sulbactam is a class A β-lactamase inhibitor with intrinsic whole-cell activity against certain bacterial species, including Acinetobacter baumannii. The clinical use of sulbactam for A. baumannii infections is of interest due to increasing multidrug ... ...

Abstract	Sulbactam is a class A β-lactamase inhibitor with intrinsic whole-cell activity against certain bacterial species, including Acinetobacter baumannii. The clinical use of sulbactam for A. baumannii infections is of interest due to increasing multidrug resistance in this pathogen. However, the molecular drivers of its antibacterial activity and resistance determinants have yet to be precisely defined. Here we show that the antibacterial activities of sulbactam vary widely across contemporary A. baumannii clinical isolates and are mediated through inhibition of the penicillin-binding proteins (PBPs) PBP1 and PBP3, with very low frequency of resistance; the rare pbp3 mutants with high levels of resistance to sulbactam are attenuated in fitness. These results support further investigation of the potential clinical utility of sulbactam.
MeSH term(s)	Acinetobacter baumannii/drug effects ; Anti-Bacterial Agents/pharmacology ; Drug Resistance, Multiple, Bacterial/physiology ; Penicillin-Binding Proteins/antagonists & inhibitors ; Sulbactam/pharmacology
Chemical Substances	Anti-Bacterial Agents ; Penicillin-Binding Proteins ; Sulbactam (S4TF6I2330)
Language	English
Publishing date	2015-03
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	217602-6
ISSN	1098-6596 ; 0066-4804
ISSN (online)	1098-6596
ISSN	0066-4804
DOI	10.1128/AAC.04808-14
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Article ; Online: Stress response and virulence functions of the Acinetobacter baumannii NfuA Fe-S scaffold protein.

Zimbler, Daniel L / Park, Thomas M / Arivett, Brock A / Penwell, William F / Greer, Samuel M / Woodruff, Tessa M / Tierney, David L / Actis, Luis A

Journal of bacteriology

2012 Volume 194, Issue 11, Page(s) 2884–2893

Abstract: To successfully establish an infection, Acinetobacter baumannii must overcome the iron starvation and oxidative stress imposed by the human host. Although previous studies have shown that ATCC 19606(T) cells acquire iron via the acinetobactin-mediated ... ...

Abstract	To successfully establish an infection, Acinetobacter baumannii must overcome the iron starvation and oxidative stress imposed by the human host. Although previous studies have shown that ATCC 19606(T) cells acquire iron via the acinetobactin-mediated siderophore system, little is known about intracellular iron metabolism and its relation to oxidative stress in this pathogen. Screening of an insertion library resulted in the isolation of the ATCC 19606(T) derivative 1644, which was unable to grow in iron-chelated media. Rescue cloning and DNA sequencing showed that the insertion inactivated a gene coding for an NfuA Fe-S cluster protein ortholog, without any effect on the expression of the acinetobactin system. The nfuA mutant was also more sensitive to hydrogen peroxide and cumene hydroperoxide than the parental strain. The iron chelation- and oxidative-stress-deficient responses of this mutant were corrected when complemented with either the ATCC 19606(T) parental allele or the Escherichia coli MG1655 nfuA ortholog. Furthermore, electron paramagnetic resonance (EPR) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analyses showed that the ATCC 19606(T) NfuA ortholog has iron-binding properties compatible with the formation of [Fe-S] cluster protein. Ex vivo and in vivo assays using human epithelial cells and Galleria mellonella, respectively, showed that NfuA is critical for bacterial growth independent of their capacity to acquire iron or the presence of excess of free iron. Taken together, these observations indicate that the A. baumannii NfuA ortholog plays a role in intracellular iron utilization and protection from oxidative-stress responses that this pathogen could encounter during the infection of the human host.
MeSH term(s)	Acinetobacter Infections/metabolism ; Acinetobacter Infections/microbiology ; Acinetobacter baumannii/genetics ; Acinetobacter baumannii/growth & development ; Acinetobacter baumannii/metabolism ; Acinetobacter baumannii/pathogenicity ; Animals ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Cell Line ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Humans ; Hydrogen Peroxide/metabolism ; Iron/metabolism ; Iron-Sulfur Proteins/genetics ; Iron-Sulfur Proteins/metabolism ; Molecular Sequence Data ; Moths ; Oxidative Stress ; Siderophores/metabolism ; Virulence
Chemical Substances	Bacterial Proteins ; Iron-Sulfur Proteins ; Siderophores ; Hydrogen Peroxide (BBX060AN9V) ; Iron (E1UOL152H7)
Language	English
Publishing date	2012-03-30
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2968-3
ISSN	1098-5530 ; 0021-9193
ISSN (online)	1098-5530
ISSN	0021-9193
DOI	10.1128/JB.00213-12
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Article ; Online: Role of the carboxy terminus of SecA in iron acquisition, protein translocation, and virulence of the bacterial pathogen Acinetobacter baumannii.

Fiester, Steven E / Nwugo, Chika C / Penwell, William F / Neary, John M / Beckett, Amber C / Arivett, Brock A / Schmidt, Robert E / Geiger, Sarah C / Connerly, Pamela L / Menke, Sharon M / Tomaras, Andrew P / Actis, Luis A

Infection and immunity

2015 Volume 83, Issue 4, Page(s) 1354–1365

Abstract: Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen that causes pneumonia and soft tissue and systemic infections. Screening of a transposon insertion library of A. baumannii ATCC 19606T resulted in the identification of the 2010 ...

Abstract	Acinetobacter baumannii is a Gram-negative opportunistic nosocomial pathogen that causes pneumonia and soft tissue and systemic infections. Screening of a transposon insertion library of A. baumannii ATCC 19606T resulted in the identification of the 2010 derivative, which, although capable of growing well in iron-rich media, failed to prosper under iron chelation. Genetic, molecular, and functional assays showed that 2010's iron utilization-deficient phenotype is due to an insertion within the 3' end of secA, which results in the production of a C-terminally truncated derivative of SecA. SecA plays a critical role in protein translocation through the SecYEG membrane channel. Accordingly, the secA mutation resulted in undetectable amounts of the ferric acinetobactin outer membrane receptor protein BauA while not affecting the production of other acinetobactin membrane protein transport components, such as BauB and BauE, or the secretion of acinetobactin by 2010 cells cultured in the presence of subinhibitory concentrations of the synthetic iron chelator 2,2'-dipyridyl. Outer membrane proteins involved in nutrient transport, adherence, and biofilm formation were also reduced in 2010. The SecA truncation also increased production of 30 different proteins, including proteins involved in adaptation/tolerance responses. Although some of these protein changes could negatively affect the pathobiology of the 2010 derivative, its virulence defect is mainly due to its inability to acquire iron via the acinetobactin-mediated system. These results together indicate that although the C terminus of the A. baumannii ATCC 19606T SecA is not essential for viability, it plays a critical role in the production and translocation of different proteins and virulence.
MeSH term(s)	2,2'-Dipyridyl/chemistry ; Acinetobacter Infections/microbiology ; Acinetobacter baumannii/genetics ; Acinetobacter baumannii/metabolism ; Acinetobacter baumannii/pathogenicity ; Adenosine Triphosphatases/genetics ; Adenosine Triphosphatases/metabolism ; Animals ; Bacterial Outer Membrane Proteins/biosynthesis ; Bacterial Outer Membrane Proteins/metabolism ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Imidazoles/metabolism ; Ion Channels/genetics ; Ion Channels/metabolism ; Iron/chemistry ; Iron/metabolism ; Membrane Transport Proteins/genetics ; Membrane Transport Proteins/metabolism ; Moths/microbiology ; Mutation ; Oxazoles/metabolism ; Protein Transport/genetics ; Protein Transport/physiology ; SEC Translocation Channels ; Virulence Factors/genetics
Chemical Substances	Bacterial Outer Membrane Proteins ; Bacterial Proteins ; Imidazoles ; Ion Channels ; Membrane Transport Proteins ; Oxazoles ; SEC Translocation Channels ; Virulence Factors ; SecA protein, Bacteria (119129-39-4) ; acinetobactin (160472-93-5) ; 2,2'-Dipyridyl (551W113ZEP) ; Iron (E1UOL152H7) ; Adenosine Triphosphatases (EC 3.6.1.-)
Language	English
Publishing date	2015-04
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	218698-6
ISSN	1098-5522 ; 0019-9567
ISSN (online)	1098-5522
ISSN	0019-9567
DOI	10.1128/IAI.02925-14
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Article ; Online: Iron acquisition functions expressed by the human pathogen Acinetobacter baumannii.

Zimbler, Daniel L / Penwell, William F / Gaddy, Jennifer A / Menke, Sharon M / Tomaras, Andrew P / Connerly, Pamela L / Actis, Luis A

Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine

2009 Volume 22, Issue 1, Page(s) 23–32

Abstract: Acinetobacter baumannii is a gram-negative bacterium that causes serious infections in compromised patients. More recently, it has emerged as the causative agent of severe infections in military personnel wounded in Iraq and Afghanistan. This pathogen ... ...

Abstract	Acinetobacter baumannii is a gram-negative bacterium that causes serious infections in compromised patients. More recently, it has emerged as the causative agent of severe infections in military personnel wounded in Iraq and Afghanistan. This pathogen grows under a wide range of conditions including iron-limiting conditions imposed by natural and synthetic iron chelators. Initial studies using the type strain 19606 showed that the iron proficiency of this pathogen depends on the expression of the acinetobactin-mediated iron acquisition system. More recently, we have observed that hemin but not human hemoglobin serves as an iron source when 19606 isogenic derivatives affected in acinetobactin transport and biosynthesis were cultured under iron-limiting conditions. This finding is in agreement with the observation that the genome of the strain 17978 has a gene cluster coding for putative hemin-acquisition functions, which include genes coding for putative hemin utilization functions and a TonBExbBD energy transducing system. This system restored enterobactin biosynthesis in an E. coli ExbBD deficient strain but not when introduced into a TonB mutant. PCR and Southern blot analyses showed that this hemin-utilization gene cluster is also present in the 19606 strain. Analysis of the 17978 genome also showed that this strain harbors genes required for acinetobactin synthesis and transport as well as a gene cluster that could code for additional iron acquisition functions. This hypothesis is in agreement with the fact that the inactivation of the basD acinetobactin biosynthetic gene did not affect the growth of A. baumannii 17978 cells under iron-chelated conditions. Interestingly, this second iron uptake gene cluster is flanked by perfect inverted repeats and includes transposase genes that are expressed transcriptionally. Also interesting is the observation that this additional cluster could not be detected in the type strain 19606, an observation that suggests some significant differences in the iron uptake capacity between these two A. baumannii strains. Transposome mutagenesis of the strain 19606 resulted in the isolation of a derivative unable to grow under iron-chelated conditions. Gene mapping and protein analysis together with complementation assays showed that a protein related to SecA, which is a component of the Sec protein secretion system in a wide range of bacteria, is needed at least for the production of the BauA acinetobactin outer membrane receptor. Furthermore, this derivative was unable to use hemin as an iron source under limiting conditions. Taken together, these results indicate that A. baumannii expresses siderophore-mediated and hemin acquisition functions, although different isolates differ in their iron acquisition capacity. Unexpectedly, the ability of this pathogen to acquire iron depends on the expression of a SecA protein secretion function, which has not been associated with iron acquisition in bacteria.
MeSH term(s)	Acinetobacter baumannii/genetics ; Acinetobacter baumannii/metabolism ; Acinetobacter baumannii/pathogenicity ; Gallium/metabolism ; Gene Expression Regulation, Bacterial ; Hemin/genetics ; Hemin/metabolism ; Hemoglobins/genetics ; Hemoglobins/metabolism ; Humans ; Iron/metabolism ; Multigene Family ; Siderophores/genetics ; Siderophores/metabolism
Chemical Substances	Hemoglobins ; Siderophores ; Hemin (743LRP9S7N) ; Gallium (CH46OC8YV4) ; Iron (E1UOL152H7)
Language	English
Publishing date	2009-01-07
Publishing country	Netherlands
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Review
ZDB-ID	1112688-7
ISSN	1572-8773 ; 0966-0844
ISSN (online)	1572-8773
ISSN	0966-0844
DOI	10.1007/s10534-008-9202-3
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In stock of ZB MED Cologne/Königswinter

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In stock of ZB MED Cologne/Königswinter

Order via subito