scholarly journals Deciphering the Function of the Outer Membrane Protein OprD Homologue of Acinetobacter baumannii

2012 ◽  
Vol 56 (7) ◽  
pp. 3826-3832 ◽  
Author(s):  
Manuella Catel-Ferreira ◽  
Rony Nehmé ◽  
Virginie Molle ◽  
Jesús Aranda ◽  
Emeline Bouffartigues ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Molecular Mechanisms ◽  
Single Channel ◽  
Resistance Mechanism ◽  
Carbapenem Resistance ◽  
Bacterial Survival ◽  
Content Type

ABSTRACTThe increasing number of carbapenem-resistantAcinetobacter baumanniiisolates is a major cause for concern which restricts therapeutic options to treat severe infections caused by this emerging pathogen. To identify the molecular mechanisms involved in carbapenem resistance, we studied the contribution of an outer membrane protein homologue of thePseudomonas aeruginosaOprD porin. Suspected to be the preferred pathway of carbapenems inA. baumannii, theoprDhomologue gene was inactivated in strain ATCC 17978. Comparison of wild-type and mutant strains did not confirm the expected increased resistance to any antibiotic tested. OprD homologue sequence analysis revealed that this protein actually belongs to an OprD subgroup but is closer to theP. aeruginosaOprQ protein, with which it could share some functions, e.g., allowing bacterial survival under low-iron or -magnesium growth conditions or under poor oxygenation. We thus overexpressed and purified a recombinant OprD homologue protein to further examine its functional properties. As a specific channel, this porin presented rather low single-channel conductance, i.e., 28 pS in 1 M KCl, and was partially closed by micro- and millimolar concentrations of Fe3+and Mg2+, respectively, but not by imipenem and meropenem or basic amino acids. TheA. baumanniiOprD homologue is likely not involved in the carbapenem resistance mechanism, but as an OprQ-like protein, it could contribute to the adaptation of this bacterium to magnesium- and/or iron-depleted environments.

scholarly journals Channel Formation by CarO, the Carbapenem Resistance-Associated Outer Membrane Protein of Acinetobacter baumannii

2005 ◽  
Vol 49 (12) ◽  
pp. 4876-4883 ◽  
Author(s):  
Axel Siroy ◽  
Virginie Molle ◽  
Christelle Lemaître-Guillier ◽  
David Vallenet ◽  
Martine Pestel-Caron ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Lipid Bilayers ◽  
Outer Membrane Protein ◽  
Carbapenem Resistance ◽  
Protein Band ◽  
Multidrug Resistant ◽  
Channel Formation ◽  
Artificial Lipid Bilayers

ABSTRACT It has been recently shown that resistance to both imipenem and meropenem in multidrug-resistant clinical strains of Acinetobacter baumannii is associated with the loss of a heat-modifiable 25/29-kDa outer membrane protein, called CarO. This study aimed to investigate the channel-forming properties of CarO. Mass spectrometry analyses of this protein band detected another 25-kDa protein (called Omp25), together with CarO. Both proteins presented similar physicochemical parameters (M w and pI). We overproduced and purified the two polypeptides as His-tagged recombinant proteins. Circular dichroism analyses demonstrated that the secondary structure of these proteins was mainly a β-strand conformation with spectra typical of porins. We studied the channel-forming properties of proteins by reconstitution into artificial lipid bilayers. In these conditions, CarO induced ion channels with a conductance value of 110 pS in 1 M KCl, whereas the Omp25 protein did not form any channels, despite its suggested porin function. The pores formed by CarO showed a slight cationic selectivity and no voltage closure. No specific imipenem binding site was found in CarO, and this protein would rather form unspecific monomeric channels.

scholarly journals Cloning and Functional Analysis of the Gene Encoding the 33- to 36-Kilodalton Outer Membrane Protein Associated with Carbapenem Resistance in Acinetobacter baumannii

2005 ◽  
Vol 49 (12) ◽  
pp. 5172-5175 ◽  
Author(s):  
Maria del Mar Tomás ◽  
Alejandro Beceiro ◽  
Astrid Pérez ◽  
David Velasco ◽  
Rita Moure ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Carbapenem Resistance ◽  
Peptide Sequence ◽  
Gene Encoding ◽  
Multiresistant Strain

ABSTRACT We investigated a multiresistant strain of Acinetobacter baumannii isolated in our hospital. Analysis of the N-terminal peptide sequence of the outer membrane proteins (OMPs) purified from the strain allowed us to clone and sequence the nucleotides of the gene encoding the 33- to 36-kDa OMP associated with carbapenem resistance in A. baumannii

scholarly journals Structure–function relationships of CarO, the carbapenem resistance-associated outer membrane protein of Acinetobacter baumannii

2011 ◽  
Vol 66 (9) ◽  
pp. 2053-2056 ◽  
Author(s):  
Manuella Catel-Ferreira ◽  
Gael Coadou ◽  
Virginie Molle ◽  
Pauline Mugnier ◽  
Patrice Nordmann ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Structure Function ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Carbapenem Resistance

scholarly journals Anaplasma phagocytophilum Outer Membrane Protein A Interacts with Sialylated Glycoproteins To Promote Infection of Mammalian Host Cells

2012 ◽  
Vol 80 (11) ◽  
pp. 3748-3760 ◽  
Author(s):  
Nore Ojogun ◽  
Amandeep Kahlon ◽  
Stephanie A. Ragland ◽  
Matthew J. Troese ◽  
Juliana E. Mastronunzio ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Anaplasma Phagocytophilum ◽  
Protein A ◽  
Host Cells ◽  
Mammalian Host ◽  
Content Type ◽  
Outer Membrane Protein A ◽  
Sialylated Glycoproteins

ABSTRACTAnaplasma phagocytophilumis the tick-transmitted obligate intracellular bacterium that causes human granulocytic anaplasmosis (HGA).A. phagocytophilumbinding to sialyl Lewis x (sLex) and other sialylated glycans that decorate P selectin glycoprotein 1 (PSGL-1) and other glycoproteins is critical for infection of mammalian host cells. Here, we demonstrate the importance ofA. phagocytophilumouter membrane protein A (OmpA) APH_0338 in infection of mammalian host cells. OmpA is transcriptionally induced during transmission feeding ofA. phagocytophilum-infected ticks on mice and is upregulated during invasion of HL-60 cells. OmpA is presented on the pathogen's surface. Sera from HGA patients and experimentally infected mice recognize recombinant OmpA. Pretreatment ofA. phagocytophilumorganisms with OmpA antiserum reduces their abilities to infect HL-60 cells. The OmpA N-terminal region is predicted to contain the protein's extracellular domain. GlutathioneS-transferase (GST)-tagged versions of OmpA and OmpA amino acids 19 to 74 (OmpA19-74) but not OmpA75-205bind to, and competitively inhibitA. phagocytophiluminfection of, host cells. Pretreatment of host cells with sialidase or trypsin reduces or nearly eliminates, respectively, GST-OmpA adhesion. Therefore, OmpA interacts with sialylated glycoproteins. This study identifies the firstA. phagocytophilumadhesin-receptor pair and delineates the region of OmpA that is critical for infection.

scholarly journals The Helicobacter pylori Autotransporter ImaA (HP0289) Modulates the Immune Response and Contributes to Host Colonization

2012 ◽  
Vol 80 (7) ◽  
pp. 2286-2296 ◽  
Author(s):  
William E. Sause ◽  
Andrea R. Castillo ◽  
Karen M. Ottemann
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Dependent Manner ◽  
Wild Type ◽  
Content Type ◽  
H Pylori ◽  
Murine Infections

ABSTRACTThe human pathogenHelicobacter pyloriemploys a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced geneHP0289, which encodes an uncharacterized outer membrane protein. We first generated an isogenicH. pylorimutant that lacksHP0289and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-typeH. pylori. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that theHP0289promoter is upregulated in the mouse stomach, and here we demonstrate thatHP0289expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that theHP0289mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-typeH. pylori. On the basis of this phenotype, we renamed HP0289 ImaA forimmunomodulatoryautotransporter protein. Our work has revealed that genes inducedin vivoplay an important role inH. pyloripathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allowH. pylorito fine tune the host immune response based on ImaA expression.

scholarly journals Estimation of Full-Length TprK Diversity in Treponema pallidum subsp. pallidum

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Amin Addetia ◽  
Michelle J. Lin ◽  
Quynh Phung ◽  
Hong Xie ◽  
Meei-Li Huang ◽  
...  
Keyword(s):  
Immune System ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Deep Sequencing ◽  
Outer Membrane Protein ◽  
Treponema Pallidum ◽  
The United States ◽  
Full Length ◽  
Variable Regions ◽  
Content Type

ABSTRACT Immune evasion and disease progression of Treponema pallidum subsp. pallidum are associated with sequence diversity in the hypervariable outer membrane protein TprK. Previous attempts to study variation within TprK have sequenced at depths insufficient to fully appreciate the hypervariable nature of the protein, failed to establish linkage between the protein’s seven variable regions, or were conducted on isolates passed through rabbits. As a consequence, a complete profile of tprK during infection in the human host is still lacking. Furthermore, prior studies examining how T. pallidum subsp. pallidum uses its repertoire of genomic donor sites to generate diversity within the variable regions of the tprK have yielded a partial understanding of this process due to the limited number of tprK alleles examined. In this study, we used short- and long-read deep sequencing to directly characterize full-length tprK alleles from T. pallidum subsp. pallidum collected from early lesions of patients attending two sexually transmitted infection clinics in Italy. We demonstrate that strains collected from cases of secondary syphilis contain significantly more unique variable region sequences and full-length TprK sequences than those from cases of primary syphilis. Our data, combined with recent data available on Chinese T. pallidum subsp. pallidum specimens, show the near-complete absence of overlap in TprK sequences among the 41 specimens profiled to date. We further estimate that the potential antigenic variability carried by TprK rivals that of current estimates of the human adaptive immune system. These data underscore the immunoevasive ability of TprK that allows T. pallidum subsp. pallidum to establish lifelong infection. IMPORTANCE Syphilis continues to be a significant public health issue in both low- and high-income countries, including the United States where the rate of syphilis infection has increased over the past 5 years. Treponema pallidum subsp. pallidum, the causative agent of syphilis, carries the outer membrane protein TprK that undergoes segmental gene conversion to constantly create new sequences. We performed full-length deep sequencing of TprK to examine TprK diversity in clinical T. pallidum subsp. pallidum strains. We then combined our results with data from all samples for which TprK deep sequencing results were available. We found almost no overlap in TprK sequences between different patients. Moreover, our data allowed us to estimate the total number of TprK variants that T. pallidum subsp. pallidum can potentially generate. Our results support how the T. pallidum subsp. pallidum TprK antigenic variation system is an equal adversary of the human immune system leading to pathogen persistence in the host.

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