scholarly journals BonA from Acinetobacter baumannii forms a divisome-localized decamer that supports outer envelope function

2020 ◽  
Author(s):  
Rhys Grinter ◽  
Faye C. Morris ◽  
Rhys A. Dunstan ◽  
Pok Man Leung ◽  
Matthew Belousoff ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Sequence Similarity ◽  
Bacterial Species ◽  
Domain Architecture ◽  
Structural Features ◽  
Clinical Strain ◽  
X Ray ◽  
X Ray Crystallography ◽  
Membrane Spanning

AbstractAcinetobacter baumannii is a high-risk pathogen due to the rapid global spread of multi-drug resistant lineages. Its phylogenetic divergence from other ESKAPE pathogens means that determinants of its antimicrobial resistance can be difficult to extrapolate from other widely studied bacteria. A recent study showed that A. baumannii upregulates production of an outer-membrane lipoprotein, which we designate BonA, in response to challenge with polymyxins. Here we show that BonA has limited sequence similarity and distinct structural features compared to lipoproteins from other bacterial species. Analyses through X-ray crystallography, small-angle X-ray scattering, electron microscopy, and multiangle light scattering demonstrate that BonA has a dual BON-domain architecture and forms a decamer via an unusual oligomerization mechanism. This analysis also indicates this decamer is transient, suggesting dynamic oligomerization plays a role in BonA function. Antisera recognizing BonA shows it is an outer membrane protein localized to the divisome. Loss of BonA modulates the density of the outer membrane, consistent with a change in its structure or link to the peptidoglycan, and prevents motility in a clinical strain (ATCC 17978). Consistent with these findings, the dimensions of the BonA decamer are sufficient to permeate the peptidoglycan layer, with the potential to form a membrane-spanning complex during cell division.

Analysis of structural MtrC models based on homology with the crystal structure of MtrF

2012 ◽  
Vol 40 (6) ◽  
pp. 1181-1185 ◽  
Author(s):  
Marcus J. Edwards ◽  
James K. Fredrickson ◽  
John M. Zachara ◽  
David J. Richardson ◽  
Thomas A. Clarke
Keyword(s):  
Crystal Structure ◽  
Outer Membrane ◽  
Domain Structure ◽  
Spectroscopic Data ◽  
Sequence Similarity ◽  
Shewanella Oneidensis ◽  
Significant Sequence Similarity ◽  
X Ray ◽  
X Ray Crystallography ◽  
Homology Models

The outer-membrane decahaem cytochrome MtrC is part of the transmembrane MtrCAB complex required for mineral respiration by Shewanella oneidensis. MtrC has significant sequence similarity to the paralogous decahaem cytochrome MtrF, which has been structurally solved through X-ray crystallography. This now allows for homology-based models of MtrC to be generated. The structure of these MtrC homology models contain ten bis-histidine-co-ordinated c-type haems arranged in a staggered cross through a four-domain structure. This model is consistent with current spectroscopic data and shows that the areas around haem 5 and haem 10, at the termini of an octahaem chain, are likely to have functions similar to those of the corresponding haems in MtrF. The electrostatic surfaces around haem 7, close to the β-barrels, are different in MtrF and MtrC, indicating that these haems may have different potentials and interact with substrates differently.

scholarly journals The Mutation of Conservative Asp268 Residue in the Peptidoglycan-Associated Domain of the OmpA Protein Affects Multiple Acinetobacter baumannii Virulence Characteristics

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1972 ◽  
Author(s):  
Jūratė Skerniškytė ◽  
Emilija Karazijaitė ◽  
Julien Deschamps ◽  
Renatas Krasauskas ◽  
Romain Briandet ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Protein A ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Clinical Strain ◽  
Infection Model ◽  
Terminal Domain ◽  
Ompa Protein

Acinetobacter baumannii is a nosocomial human pathogen of increasing concern due to its multidrug resistance profile. The outer membrane protein A (OmpA) is an abundant bacterial cell surface component involved in A. baumannii pathogenesis. It has been shown that the C-terminal domain of OmpA is located in the periplasm and non-covalently associates with the peptidoglycan layer via two conserved amino acids, thereby anchoring OmpA to the cell wall. Here, we investigated the role of one of the respective residues, D268 in OmpA of A. baumannii clinical strain Ab169, on its virulence characteristics by complementing the ΔompA mutant with the plasmid-borne ompAD268A allele. We show that while restoring the impaired biofilm formation of the ΔompA strain, the Ab169ompAD268A mutant tended to form bacterial filaments, indicating the abnormalities in cell division. Moreover, the Ab169 OmpA D268-mediated association to peptidoglycan was required for the manifestation of twitching motility, desiccation resistance, serum-induced killing, adhesion to epithelial cells and virulence in a nematode infection model, although it was dispensable for the uptake of β-lactam antibiotics by outer membrane vesicles. Overall, the results of this study demonstrate that the OmpA C-terminal domain-mediated association to peptidoglycan is critical for a number of virulent properties displayed by A. baumannii outside and within the host.

scholarly journals N-Acetylcysteine Selectively Antagonizes the Activity of Imipenem in Pseudomonas aeruginosa by an OprD-Mediated Mechanism

2015 ◽  
Vol 59 (6) ◽  
pp. 3246-3251 ◽  
Author(s):  
Jerónimo Rodríguez-Beltrán ◽  
Gabriel Cabot ◽  
Estela Ynés Valencia ◽  
Coloma Costas ◽  
German Bou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Bacterial Species ◽  
Outer Membrane Proteins ◽  
Antibiotic Activity ◽  
Simultaneous Treatment ◽  
Content Type ◽  
Sds Page

ABSTRACTThe modulating effect ofN-acetylcysteine (NAC) on the activity of different antibiotics has been studied inPseudomonas aeruginosa. Our results demonstrate that, in contrast to previous reports, only the activity of imipenem is clearly affected by NAC. MIC and checkerboard determinations indicate that the NAC-based modulation of imipenem activity is dependent mainly on OprD. SDS-PAGE of outer membrane proteins (OMPs) after NAC treatments demonstrates that NAC does not modify the expression of OprD, suggesting that NAC competitively inhibits the uptake of imipenem through OprD. Similar effects on imipenem activity were obtained withP. aeruginosaclinical isolates. Our results indicate that imipenem-susceptibleP. aeruginosastrains become resistant upon simultaneous treatment with NAC and imipenem. Moreover, the generality of the observed effects of NAC on antibiotic activity was assessed with two additional bacterial species,Escherichia coliandAcinetobacter baumannii. Caution should be taken during treatments, as the activity of imipenem may be modified by physiologically attainable concentrations of NAC, particularly during intravenous and nebulized regimes.

Two new zinc(II) and mercury(II) complexes based on N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide): synthesis, crystal structures and antibacterial activities

2020 ◽  
Vol 76 (5) ◽  
pp. 476-482
Author(s):  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M. Al-Karawi ◽  
Adil A. Awad ◽  
Necmi Dege ◽  
Sevgi Kansız ◽  
...  
Keyword(s):  
Organic Ligand ◽  
Antibacterial Activities ◽  
Structural Features ◽  
Bacterial Strains ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Growth Inhibitory ◽  
The Difference

Reaction of N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide), C20H18F2N4O2, (LF ), with zinc chloride and mercury(II) chloride produced different types and shapes of neutral coordination complexes, namely, dichlorido[N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ2 N,O]zinc(II), [ZnCl2(C20H18F2N4O2)], (1), and dichlorido[N,N′-(cyclohexane-1,2-diylidene)bis(4-fluorobenzohydrazide)-κ4 O,N,N′,O′]mercury(II), [HgCl2(C20H18F2N4O2)], (2). The organic ligand and its metal complexes are characterized using various techniques: IR, UV–Vis and nuclear magnetic resonance (NMR) spectroscopies, in addition to powder X-ray diffraction (PXRD), single-crystal X-ray crystallography and microelemental analysis. Depending upon the data from these analyses and measurements, a typical tetrahedral geometry was confirmed for zinc complex (1), in which the ZnII atom is located outside the bis(benzhydrazone) core. The HgII atom in (2) is found within the core and has a common octahedral structure. The in vitro antibacterial activities of the prepared compounds were evaluated against two different bacterial strains, i.e. gram positive Bacillus subtilis and gram negative Pseudomonas aeruginosa bacteria. The prepared compounds exhibited differentiated growth-inhibitory activities against these two bacterial strains based on the difference in their lipophilic nature and structural features.

scholarly journals Molecular mechanisms of enzyme dysfunction in human phosphoglucomutase-1 deficiency

2019 ◽  
Author(s):  
◽  
Kyle Matthew Stiers
Keyword(s):  
Molecular Mechanisms ◽  
Structural Features ◽  
Therapeutic Interventions ◽  
Structural Studies ◽  
X Ray ◽  
Missense Variants ◽  
X Ray Crystallography ◽  
Ancient Lineage ◽  
Research Opportunity

Human phosphoglucomutase-1 (PGM1) belongs to the [alpha]-D-phosphohexomutase superfamily, an ancient lineage of enzymes critical for carbohydrate metabolism. PGM1 catalyzes the interconversion of glucose-1-phosphate and glucose-6-phosphate, acting as the pivot between energy storage and utilization. Recently, PGM1 has been implicated as the monogenic cause of an inherited metabolic disease in humans, called PGM1 deficiency. The disease presents with highly variable phenotype in patients and is difficult to diagnose. Furthermore, genotype-phenotype relationships remain unclear-even in siblings with the same missense variants, no obvious correlation exists. PGM1 deficiency is a unique research opportunity due to the lack of clear rationale for varying effects of missense variants, availability of patient data, favorable in vitro behavior of recombinantly expressed PGM1, and the limited number of structural studies characterizing individual missense variants. In this work we have characterized multiple molecular mechanisms of disease through X-ray crystallography and biochemistry. Thus, this work provides a foundation for physicians to make much more accurate prognostic decisions when advising patients, identifies variants with possible therapeutic interventions, and informs us of key dynamics and structural features required for proper functioning of human PGM1.

scholarly journals Cocktailed fragment screening by X-ray crystallography of the antibacterial target undecaprenyl pyrophosphate synthase from Acinetobacter baumannii

2020 ◽  
Vol 76 (1) ◽  
pp. 40-46
Author(s):  
James H. Thorpe ◽  
Ian D. Wall ◽  
Robert H. Sinnamon ◽  
Amy N. Taylor ◽  
Robert A. Stavenger
Keyword(s):  
Drug Discovery ◽  
Acinetobacter Baumannii ◽  
Structural Data ◽  
X Ray ◽  
Traditional Medicines ◽  
X Ray Crystallography ◽  
Fragment Screening ◽  
Binding Pockets ◽  
Antibacterial Target ◽  
Robustness Check

Direct soaking of protein crystals with small-molecule fragments grouped into complementary clusters is a useful technique when assessing the potential of a new crystal system to support structure-guided drug discovery. It provides a robustness check prior to any extensive crystal screening, a double check for assay binding cutoffs and structural data for binding pockets that may or may not be picked out in assay measurements. The structural output from this technique for three novel fragment molecules identified to bind to the antibacterial target Acinetobacter baumannii undecaprenyl pyrophosphate synthase are reported, and the different physicochemical requirements of a successful antibiotic are compared with traditional medicines.

scholarly journals Structure and Stoichiometry of the Ton Molecular Motor

2020 ◽  
Vol 21 (2) ◽  
pp. 375 ◽  
Author(s):  
Herve Celia ◽  
Nicholas Noinaj ◽  
Susan K Buchanan
Keyword(s):  
Outer Membrane ◽  
Mode Of Action ◽  
Molecular Motor ◽  
Proton Gradient ◽  
Gram Negative Bacteria ◽  
Periplasmic Space ◽  
Inner Membrane ◽  
Gram Negative ◽  
X Ray ◽  
X Ray Crystallography

The Ton complex is a molecular motor that uses the proton gradient at the inner membrane of Gram-negative bacteria to generate force and movement, which are transmitted to transporters at the outer membrane, allowing the entry of nutrients into the periplasmic space. Despite decades of investigation and the recent flurry of structures being reported by X-ray crystallography and cryoEM, the mode of action of the Ton molecular motor has remained elusive, and the precise stoichiometry of its subunits is still a matter of debate. This review summarizes the latest findings on the Ton system by presenting the recently reported structures and related reports on the stoichiometry of the fully assembled complex.

scholarly journals Structural features and near infra-red (NIR) luminescence of isomeric Yb(iii) bipyridyl-N,N′-dioxide coordination polymers

2015 ◽  
Vol 44 (29) ◽  
pp. 13378-13383 ◽  
Author(s):  
Gail M. Sequeira ◽  
Wayne Y. Tan ◽  
Evan G. Moore
Keyword(s):  
Coordination Polymers ◽  
Structural Characterization ◽  
Lanthanide Complexes ◽  
Structural Features ◽  
X Ray ◽  
X Ray Crystallography ◽  
Infra Red ◽  
Nir Luminescence

The synthesis and structural characterization of a series of lanthanide complexes formed from YbX3 salts (X = NO3− or CF3SO3−) and the isomeric 4,4′-bipyridine-N,N′-dioxide (4,4′-bpdo) or 3,3′-bipyridine-N,N′-dioxide (3,3′-bpdo) ligands has been undertaken by X-ray crystallography.

scholarly journals Effect of the ruffled porphyrin ring on electronic structures: structure and characterization of [Fe(TalkylP)(OClO3)] and [Fe(TPrP)(THF)2]ClO4 (alkyl = Ethyl, Et and n-Propyl, Pr)

2013 ◽  
Vol 17 (01n02) ◽  
pp. 118-124 ◽  
Author(s):  
Ming Li ◽  
Allen G. Oliver ◽  
Teresa J. Neal ◽  
Charles E. Schulz ◽  
W. Robert Scheidt
Keyword(s):  
Electronic Structures ◽  
Structural Parameters ◽  
Structural Features ◽  
Magnetic Data ◽  
Porphyrin Ring ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
X Ray Crystallography ◽  
Intermediate Spin

We report the synthesis of Fe(TalkylP)(OClO3)] (alkyl = ethyl and propyl) and [Fe(TPrP)(THF)2]ClO4 , which are characterized by UV-vis, EPR, X-ray crystallography, and solid-state magnetic susceptibilities. The macrocycles of all three complexes are ruffled, all of the structural features for [Fe(TEtP(OClO3)] and [Fe(TPrP)(OClO3)] are characteristic of the nearly pure S = 3/2 state, while the structural parameters for [Fe(TPrP)(THF)2]ClO4 feature a pure intermediate-spin (S = 3/2) state, which are all consistent with EPR and magnetic data. It is clear from these studies that the ruffled conformation plays a significant role in affecting the extent of S = 3/2 character.

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