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Saw WG, Le KCM, Shin J, Kwek JHM, Wong CF, Ragunathan P, Fong TC, Müller V, Grüber G. Atomic insights of an up and down conformation of the Acinetobacter baumannii F 1 -ATPase subunit ε and deciphering the residues critical for ATP hydrolysis inhibition and ATP synthesis. FASEB J 2023; 37:e23040. [PMID: 37318822 DOI: 10.1096/fj.202300175rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/23/2023] [Accepted: 06/05/2023] [Indexed: 06/16/2023]
Abstract
The Acinetobacter baumannii F1 FO -ATP synthase (α3 :β3 :γ:δ:ε:a:b2 :c10 ), which is essential for this strictly respiratory opportunistic human pathogen, is incapable of ATP-driven proton translocation due to its latent ATPase activity. Here, we generated and purified the first recombinant A. baumannii F1 -ATPase (AbF1 -ATPase) composed of subunits α3 :β3 :γ:ε, showing latent ATP hydrolysis. A 3.0 Å cryo-electron microscopy structure visualizes the architecture and regulatory element of this enzyme, in which the C-terminal domain of subunit ε (Abε) is present in an extended position. An ε-free AbF1 -ɑβγ complex generated showed a 21.5-fold ATP hydrolysis increase, demonstrating that Abε is the major regulator of AbF1 -ATPase's latent ATP hydrolysis. The recombinant system enabled mutational studies of single amino acid substitutions within Abε or its interacting subunits β and γ, respectively, as well as C-terminal truncated mutants of Abε, providing a detailed picture of Abε's main element for the self-inhibition mechanism of ATP hydrolysis. Using a heterologous expression system, the importance of Abε's C-terminus in ATP synthesis of inverted membrane vesicles, including AbF1 FO -ATP synthases, has been explored. In addition, we are presenting the first NMR solution structure of the compact form of Abε, revealing interaction of its N-terminal β-barrel and C-terminal ɑ-hairpin domain. A double mutant of Abε highlights critical residues for Abε's domain-domain formation which is important also for AbF1 -ATPase's stability. Abε does not bind MgATP, which is described to regulate the up and down movements in other bacterial counterparts. The data are compared to regulatory elements of F1 -ATPases in bacteria, chloroplasts, and mitochondria to prevent wasting of ATP.
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Affiliation(s)
- Wuan-Geok Saw
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
| | - Khoa Cong Minh Le
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Joon Shin
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Jes Hui Min Kwek
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Chui Fann Wong
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Priya Ragunathan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Tuck Choy Fong
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Volker Müller
- Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt, Germany
| | - Gerhard Grüber
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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Hubloher JJ, Zeidler S, Lamosa P, Santos H, Averhoff B, Müller V. Trehalose-6-phosphate-mediated phenotypic change in Acinetobacter baumannii. Environ Microbiol 2020; 22:5156-5166. [PMID: 32618111 DOI: 10.1111/1462-2920.15148] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/22/2020] [Accepted: 06/29/2020] [Indexed: 12/12/2022]
Abstract
The stress protectant trehalose is synthesized in Acinetobacter baumannii from UPD-glucose and glucose-6-phosphase via the OtsA/OtsB pathway. Previous studies proved that deletion of otsB led to a decreased virulence, the inability to grow at 45°C and a slight reduction of growth at high salinities indicating that trehalose is the cause of these phenotypes. We have questioned this conclusion by producing ∆otsA and ∆otsBA mutants and studying their phenotypes. Only deletion of otsB, but not deletion of otsA or otsBA, led to growth impairments at high salt and high temperature. The intracellular concentrations of trehalose and trehalose-6-phosphate were measured by NMR or enzymatic assay. Interestingly, none of the mutants accumulated trehalose any more but the ∆otsB mutant with its defect in trehalose-6-phosphate phosphatase activity accumulated trehalose-6-phosphate. Moreover, expression of otsA in a ∆otsB background under conditions where trehalose synthesis is not induced led to growth inhibition and the accumulation of trehalose-6-phosphate. Our results demonstrate that trehalose-6-phosphate affects multiple physiological activities in A. baumannii ATCC 19606.
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Affiliation(s)
- Josephine Joy Hubloher
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Sabine Zeidler
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Pedro Lamosa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Helena Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
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Gilani M, Latif M, Gilani M, Saad N, Ansari M, Gilani M, Waseem H, Naeem A. Efficacy of Antimicrobials Against Multidrug-Resistant Acinetobacter baumannii from Patients in a Tertiary Care Hospital. Microb Drug Resist 2019; 26:681-684. [PMID: 31829792 DOI: 10.1089/mdr.2019.0004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction: In just two decades Acinetobacter baumannii has attained considerable importance, evolving from an insignificant organism to a leading pathogen especially in intensive care unit settings globally. Treatment options are already very limited and have almost run out due to the rapid emergence of antimicrobial resistance. Evaluation of antimicrobials that are currently in use to determine their effectiveness against multidrug-resistant (MDR) strains and developing newer options is of utmost importance. We thus set out to determine the efficacy of routinely used antibiotics against MDR A. baumannii. Materials and Methods: This was a cross-sectional study conducted at the Department of Microbiology, Army Medical College, National University of Medical Sciences (Rawalpindi, Pakistan) from December 2015 to June 2016. The organisms were identified on the basis of colony morphology, gram staining, catalase, oxidase, motility test, and API (analytical profile index) 20NE. The organisms were considered to be MDR when the isolate was found to be resistant to at least one agent in more than three antimicrobial groups. Antibiotic sensitivity was determined using the modified Kirby-Bauer disc diffusion method according to Clinical Laboratory Standards Institute (CLSI) guidelines. Results: The 77 isolates were found to have good sensitivity to tigecycline (94.8%) and minocycline (80.5%). Most of the isolates were resistant to other routinely used antibiotics. Conclusion: A few antibiotics, tigecycline and minocycline, are still effective against these MDR A. baumannii. We need to remain up to date regarding the efficacy of antibiotics to effectively treat patients with these MDR bacteria.
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Affiliation(s)
- Mehreen Gilani
- Department of Microbiology, Army Medical College, National University of Medical Sciences, Rawalpindi, Pakistan
| | - Mahwish Latif
- Department of Microbiology, Army Medical College, National University of Medical Sciences, Rawalpindi, Pakistan
| | - Mehwish Gilani
- Armed Forces Institute of Pathology, Rawalpindi, Pakistan
| | - Nadia Saad
- Department of Microbiology, Army Medical College, National University of Medical Sciences, Rawalpindi, Pakistan
| | - Maliha Ansari
- Department of Microbiology, Army Medical College, National University of Medical Sciences, Rawalpindi, Pakistan
| | | | - Hafsa Waseem
- Department of Microbiology, Army Medical College, National University of Medical Sciences, Rawalpindi, Pakistan
| | - Afnan Naeem
- Department of Microbiology, Army Medical College, National University of Medical Sciences, Rawalpindi, Pakistan
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Zeidler S, Hubloher J, König P, Ngu ND, Scholz A, Averhoff B, Müller V. Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii. Microbiologyopen 2018; 7:e00614. [PMID: 29575790 PMCID: PMC6291793 DOI: 10.1002/mbo3.614] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/06/2018] [Accepted: 02/06/2018] [Indexed: 01/05/2023] Open
Abstract
Mannitol is the major compatible solute, next to glutamate, synthesized by the opportunistic human pathogen Acinetobacter baumannii under low water activities. The key enzyme for mannitol biosynthesis, MtlD, was identified. MtlD is highly similar to the bifunctional mannitol‐1‐phosphate dehydrogenase/phosphatase from Acinetobacter baylyi. After deletion of the mtlD gene from A. baumannii ATCC 19606T cells no longer accumulated mannitol and growth was completely impaired at high salt. Addition of glycine betaine restored growth, demonstrating that mannitol is an important compatible solute in the human pathogen. MtlD was heterologously produced and purified. Enzyme activity was strictly salt dependent. Highest stimulation was reached at 600 mmol/L NaCl. Addition of different sodium as well as potassium salts restored activity, with highest stimulations up to 41 U/mg protein by sodium glutamate. In contrast, an increase in osmolarity by addition of sugars did not restore activity. Regulation of mannitol synthesis was also assayed at the transcriptional level. Reporter gene assays revealed that expression of mtlD is strongly dependent on high osmolarity, not discriminating between different salts or sugars. The presence of glycine betaine or its precursor choline repressed promoter activation. These data indicate a dual regulation of mannitol production in A. baumannii, at the transcriptional and the enzymatic level, depending on high osmolarity.
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Affiliation(s)
- Sabine Zeidler
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Josephine Hubloher
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Patricia König
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Ngoc Dinh Ngu
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Anica Scholz
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Beate Averhoff
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
| | - Volker Müller
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt am Main, Frankfurt, Germany
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Zeidler S, Hubloher J, Schabacker K, Lamosa P, Santos H, Müller V. Trehalose, a temperature- and salt-induced solute with implications in pathobiology of Acinetobacter baumannii. Environ Microbiol 2017; 19:5088-5099. [PMID: 29124876 DOI: 10.1111/1462-2920.13987] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 11/03/2017] [Indexed: 01/01/2023]
Abstract
Acinetobacter baumannii is an opportunistic human pathogen that has become a global threat to healthcare institutions worldwide. A major factor contributing to success of this bacterium is its outstanding ability to survive on dry surfaces. The molecular basis for desiccation resistance is not completely understood. This study focused on growth under osmotic stress and aimed to identify the pool of compatible solutes synthesized in response to these low water activity conditions. A. baumannii produced mannitol as compatible solute, but in contrast to Acinetobacter baylyi, also trehalose was accumulated in response to increasing NaCl concentrations. The genome of A. baumannii encodes a trehalose-6-phosphate phosphatase (OtsB) and a trehalose-6-phosphate synthase (OtsA). Deletion of otsB abolished trehalose formation, demonstrating that otsB is essential for trehalose biosynthesis. Growth of the mutant was neither impaired at low salt nor at 500 mM NaCl, but it did not grow at high temperatures, indicating a dual function of trehalose in osmo- and thermoprotection. This led us to analyse temperature dependence of trehalose formation. Indeed, expression of otsB was not only induced by high osmolarity but also by high temperature. Concurrently, trehalose was accumulated in cells grown at high temperature. Taken together, these data point to an important role of trehalose in A. baumannii beyond osmoprotection.
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Affiliation(s)
- Sabine Zeidler
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Josephine Hubloher
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Kim Schabacker
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
| | - Pedro Lamosa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Helena Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Germany
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Lopalco P, Stahl J, Annese C, Averhoff B, Corcelli A. Identification of unique cardiolipin and monolysocardiolipin species in Acinetobacter baumannii. Sci Rep 2017; 7:2972. [PMID: 28592862 PMCID: PMC5462836 DOI: 10.1038/s41598-017-03214-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 04/20/2017] [Indexed: 01/05/2023] Open
Abstract
Acidic glycerophospholipids play an important role in determining the resistance of Gram-negative bacteria to stress conditions and antibiotics. Acinetobacter baumannii, an opportunistic human pathogen which is responsible for an increasing number of nosocomial infections, exhibits broad antibiotic resistances. Here lipids of A. baumannii have been analyzed by combined MALDI-TOF/MS and TLC analyses; in addition GC-MS analyses of fatty acid methyl esters released by methanolysis of membrane phospholipids have been performed. The main glycerophospholipids are phosphatidylethanolamine, phosphatidylglycerol, acyl-phosphatidylglycerol and cardiolipin together with monolysocardiolipin, a lysophospholipid only rarely detected in bacterial membranes. The major acyl chains in the phospholipids are C16:0 and C18:1, plus minor amounts of short chain fatty acids. The structures of the cardiolipin and monolysocardiolipin have been elucidated by post source decay mass spectrometry analysis. A large variety of cardiolipin and monolysocardiolipin species were found in A. baumannii. Similar lysocardiolipin levels were found in the two clinical strains A. baumannii ATCC19606T and AYE whereas in the nonpathogenic strain Acinetobacter baylyi ADP1 lysocardiolipin levels were highly reduced.
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Affiliation(s)
- Patrizia Lopalco
- Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Julia Stahl
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Cosimo Annese
- Italian National Council for Research - Institute for the Chemistry of OrganoMetallic Compounds (CNR-ICCOM), Bari, Italy
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Angela Corcelli
- Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy. .,Italian National Council for Research - Institute for Chemical-Physical Processes (CNR- IPCF), Bari, Italy.
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The Acinetobacter Outer Membrane Contains Multiple Specific Channels for Carbapenem β-Lactams as Revealed by Kinetic Characterization Analyses of Imipenem Permeation into Acinetobacter baylyi Cells. Antimicrob Agents Chemother 2017; 61:AAC.01737-16. [PMID: 28069648 DOI: 10.1128/aac.01737-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/28/2016] [Indexed: 12/31/2022] Open
Abstract
The number and type of outer membrane (OM) channels responsible for carbapenem uptake in Acinetobacter are still not well defined. Here, we addressed these questions by using Acinetobacter baylyi as a model species and a combination of methodologies aimed to characterize OM channels in their original membrane environment. Kinetic and competition analyses of imipenem (IPM) uptake by A. baylyi whole cells allowed us to identify different carbapenem-specific OM uptake sites. Comparative analyses of IPM uptake by A. baylyi wild-type (WT) cells and ΔcarO mutants lacking CarO indicated that this OM protein provided a carbapenem uptake site displaying saturable kinetics and common binding sites for basic amino acids compatible with a specific channel. The kinetic analysis uncovered another carbapenem-specific channel displaying a somewhat lower affinity for IPM than that of CarO and, in addition, common binding sites for basic amino acids as determined by competition studies. The use of A. baylyi gene deletion mutants lacking OM proteins proposed to function in carbapenem uptake in Acinetobacter baumannii indicated that CarO and OprD/OccAB1 mutants displayed low but consistent reductions in susceptibility to different carbapenems, including IPM, meropenem, and ertapenem. These two mutants also showed impaired growth on l-Arg but not on other carbon sources, further supporting a role of CarO and OprD/OccAB1 in basic amino acid and carbapenem uptake. A multiple-carbapenem-channel scenario may provide clues to our understanding of the contribution of OM channel loss or mutation to the carbapenem-resistant phenotype evolved by pathogenic members of the Acinetobacter genus.
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