Cellular Microbiology (Cell Microbiol )

Publisher: Blackwell Publishing

Description

Cellular Microbiology publishes the best original scientific contribution of the intersection of microbial on host-cell biology. The focus is the host cell responses elicited by the interaction of micro-organisms. Equal emphasis is placed on responses to prokaryotic, viral and eukaryotic micro-organisms. In addition to mammalion systems, papers addressing other hosts such as plants and insects are strongly encourage. Exploitation of host cell structure; Modification of cell signalling pathways; Molecular responses of the host cell; Responses of tissues and whole organs; Systemic effects elicited by micro-organisms; Induction of immune response; Modulation and exploitation of immune response; Remodelling of tissues; Co-pathogen interactions.

  • Impact factor
    4.81
  • 5-year impact
    5.09
  • Cited half-life
    5.30
  • Immediacy index
    1.31
  • Eigenfactor
    0.03
  • Article influence
    1.85
  • Website
    Cellular Microbiology website
  • Other titles
    Cellular microbiology (Online)
  • ISSN
    1462-5822
  • OCLC
    42869627
  • Material type
    Document, Periodical, Internet resource
  • Document type
    Internet Resource, Computer File, Journal / Magazine / Newspaper

Publisher details

Blackwell Publishing

  • Pre-print
    • Author can archive a pre-print version
  • Post-print
    • Author cannot archive a post-print version
  • Restrictions
    • Some journals impose embargoes typically of 6 or 12 months, occasionally of 24 months
    • no listing of affected journals available as yet
  • Conditions
    • See Wiley-Blackwell entry for articles after February 2007
    • Publisher's version/PDF cannot be used
    • On author's server, institutional server or subject-based server
    • Server must be non-commercial
    • Publisher copyright and source must be acknowledged with set statement ("The definitive version is available at www.blackwell-synergy.com")
    • Articles in some journals can be made Open Access on payment of additional charge
    • 'Blackwell Publishing' is an imprint of 'Wiley'
  • Classification
    ​ yellow

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Microbial pathogens that colonize multiple tissues commonly produce adhesive surface proteins that mediate attachment to cells and/or extracellular matrix in target organs. Many of these 'adhesins' bind to multiple ligands, complicating efforts to understand the role of each ligand-binding activity. Borrelia burgdorferi, the causative agent of Lyme disease, produces BBK32, first identified as a fibronectin-binding adhesin that promotes skin and joint colonization. BBK32 also binds to glycosaminoglycan (GAG), which, like fibronectin is ubiquitously present on cell surfaces. To determine which binding activity is relevant for BBK32-promoted infectivity, we generated a panel of BBK32 truncation and internal deletion mutants, and identified variants specifically defective for binding to either fibronectin or GAG. These variants promoted bacterial attachment to different mammalian cell types in vitro, suggesting that fibronectin and GAG binding may play distinct roles during infection. Intravenous inoculation of mice with a high-passage non-infectious B. burgdorferi strain that produced wild type BBK32 or BBK32 mutants defective for GAG or fibronectin binding, revealed that only GAG-binding activity was required for significant localization to joints at 60 minutes post-infection. An otherwise infectious B. burgdorferi strain producing BBK32 specifically deficient in fibronectin binding was fully capable of both skin and joint colonization in the murine model, whereas a strain producing BBK32 selectively attenuated for GAG binding colonized the inoculation site but not knee or tibiotarsus joints. Thus, the BBK32 fibronectin- and GAG-binding activities are separable in vivo, and BBK32-mediated GAG binding, but not fibronectin binding, contributes to joint colonization. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Upon infection, Legionella pneumophila uses the Dot/Icm type IV secretion system to translocate effector proteins from the Legionella-containing vacuole (LCV) into the host cell cytoplasm. The effectors target a wide array of host cellular processes that aid LCV biogenesis, including the manipulation of membrane trafficking. In this study, we used a hidden Markov model screen to identify two novel, non-eukaryotic SNARE homologs: the bacterial LseA and viral VshA proteins. We characterized LseA as a Dot/Icm effector of L. pneumophila, which has close homology to the Qc-SNARE subfamily. The lseA gene was present in multiple sequenced L. pneumophila strains including Corby and was well distributed amongst L. pneumophila clinical and environmental isolates. Employing a variety of biochemical, cell biological and microbiological techniques, we found that farnesylated LseA localized to membranes associated with the Golgi complex in mammalian cells and LseA interacted with a subset of Qa-, Qb- and R-SNAREs in host cells. Our results suggested that LseA acts as a SNARE protein and has the potential to regulate or mediate membrane fusion events in Golgi-associated pathways. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Salmonella enterica Typhimurium induces intestinal inflammation through the activity of type III secreted effector (T3SE) proteins. Our prior results indicate that the secretion of the T3SE SipA and the ability of SipA to induce epithelial cell responses that lead to induction of PMN transepithelial migration are not coupled to its direct delivery into epithelial cells from Salmonella. We therefore tested the hypothesis that SipA interacts with a membrane protein located at the apical surface of intestinal epithelial cells. Employing a split ubiquitin yeast-two-hybrid screen, we identified the tetraspanning membrane protein, PERP (p53-effector related to PMP-22), as a SipA binding partner. SipA and PERP appear to have intersecting activities as we found PERP to be involved in proinflammatory pathways shown to be regulated by SipA. In sum, our studies reveal a critical role for PERP in the pathogenesis of S. Typhimurium, and for the first time demonstrate that SipA, a T3SE protein, can engage a host protein at the epithelial surface. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Macrophages are the primary habitat of pathogenic mycobacteria during infections. The current research about the host pathogen interaction on the cellular level is still going on. The present study proves the potential of Raman microspectroscopy as a label-free and non-invasive method to investigate intracellular mycobacteria in situ. Therefore, macrophages were infected with M. gordonae, a mycobacterium known to cause inflammation linked to intracellular survival in macrophages. Here, we show that Raman maps provided spatial and spectral information about the position of bacteria within determined cell margins of macrophages in two dimensional scans and in three dimensional image stacks. Simultaneously, the relative intracellular concentration and distributions of cellular constituents such as DNA, proteins and lipids provided phenotypic information about the infected macrophages. Locations of bacteria outside or close to the outer membrane of the macrophages were notably different in their spectral pattern compared to intracellular once. Furthermore, accumulations of bacteria inside of macrophages exhibit distinct spectral/molecular information due to the chemical composition of the intracellular microenvironment. The data show that the connection of microscopically and chemically gained information provided by Raman microspectroscopy offers a new analytical way to detect and to characterize the mycobacterial infection of macrophages. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Acquired protection from Plasmodium falciparum malaria takes years to develop, probably reflecting the ability of the parasites to evade immunity. A recent example of this is the binding of the Fc region of IgM to VAR2CSA-type PfEMP1. This interferes with specific IgG recognition and phagocytosis of opsonized infected erythrocytes (IEs) without compromising the placental IE adhesion mediated by this PfEMP1 type. IgM also binds via Fc to several other PfEMP1 proteins, where it has been proposed to facilitate rosetting (binding of uninfected erythrocytes to a central IE). To further dissect the functional role of Fc -mediated IgM binding to PfEMP1, we studied the PfEMP1 protein HB3VAR06, which mediates rosetting and binds IgM. Binding of IgM to this PfEMP1 involved the Fc domains Cμ3-Cμ4 in IgM and the penultimate DBL domain (DBLζ2) at the C-terminus of HB3VAR06. However, IgM binding did not inhibit specific IgG labelling of HB3VAR06 or shield IgG-opsonized IEs from phagocytosis. Instead, IgM was required for rosetting, and each pentameric IgM molecule could bind two HB3VAR06 molecules. Together, our data indicate that the primary function of Fc -mediated IgM binding in rosetting is not to shield IE from specific IgG recognition and phagocytosis as in VAR2CSA-type PfEMP1. Rather, the function appears to be strengthening of IE-erythrocyte interactions. In conclusion, our study provides new evidence on the molecular details and functional significance of rosetting, a long-recognized marker of parasites that cause severe P. falciparum malaria. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: The actin cytoskeleton is key to the barrier function of epithelial cells, by permitting the establishment and maintenance of cell-cell junctions and cell adhesion to the basal matrix. Actin exists under monomeric and polymerized filamentous form and its polymerization following activation of nucleation promoting factors generates pushing forces, required to propell intracellular microorganisms in the host cell cytosol or for the formation of cell extensions that engulf bacteria. Actin filaments can associate with adhesion receptors at the plasma membrane via cytoskeletal linkers. Membrane anchored to actin filaments are then subjected to the retrograde flow, that may pull membrane-bound bacteria inside the cell. To induce its internalization by normally non-phagocytic cells, bacteria need to establish adhesive contacts and trick the cell into apply pulling forces, and/ or to generate protrusive forces that deform the membrane surrounding its contact site. In this review, we will focus on recent findings on actin cytoskeleton reorganization within epithelial cells during invasion and cell-to-cell spreading by the enteroinvasive pathogen Shigella, the causative agent of bacillary dysentery. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Enterovirus 71 (EV71) is an emerging life-threatening pathogen particularly in the Asia-Pacific region. The major pathogenic feature in EV71-infected cells is apoptosis. However, which molecular mechanism mainly contributes to EV71-induced apoptosis is not investigated thoroughly. MiRNAs, the newly discovered molecules, govern a wide range of biological functions through post-transcriptional regulation including viral pathogenesis. Whether miRNAs and mRNAs coordinate to trigger host cell apoptosis in EV71 infection was investigated in this study. We conducted an apoptosis-oriented approach by using both mRNA and miRNA profiling and bioinformatic analysis. We identified two major apoptosis-associated signaling pathways, BAD phosphorylation and p53-dependent apoptosis pathways, in which SOS1 and GADD45β were predicted as targets of miR-146a and miR-370, respectively. Luciferase reporter assays and Western blots demonstrated the negative regulation between miR-146a and SOS1 and between miR-370 and GADD45β. Silencing of miR-146a restored SOS1 expression and partially attenuated EV71 infection-induced apoptosis. Conversely, ectopic expression of miR-370 decreased virus infection-induced GADD45β expression and also diminished apoptosis. Finally, the transfection of antagomiR-146a and miR-370 contributed to attenuating EV71 infection-induced apoptosis. Herein we clearly demonstrate that EV71-induced cell apoptosis is partly governed by altered miRNAs. This article is protected by copyright. All rights reserved.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Hepatitis B virus morphogenesis is accompanied by the production and release of non-enveloped capsids/nucleocapsids. Capsid particles are formed inside the cell cytosol by multimerization of core protein subunits and ultimately exported in an uncommon coatless state. Here, we investigated potential roles of Rab GTPases in capsid formation and trafficking by using RNA interference and overexpression studies. Naked capsid release does not require functions of the endosome-associated Rab5, Rab7, and Rab27 proteins, but depends on functional Rab33B, a GTPase participating in autophagosome formation via interaction with the Atg5-Atg12/Atg16L1 complex. During capsid formation, Rab33B acts in conjunction with its effector, as silencing of Atg5, Atg12, and Atg16L1 also impaired capsid egress. Analysis of capsid maturation steps revealed that Rab33B and Atg5/12/16L1 are required for proper particle assembly and/or stability. In support, the capsid protein was found to interact with Atg5 and colocalize with Atg5/12/16L1, implicating that autophagy pathway functions are involved in capsid biogenesis. However, a complete and functional autophagy pathway is dispensable for capsid release, as judged by knockdown analysis of Atg8/LC3 family members and pharmaceutical ablation of canonical autophagy. Experiments aimed at analyzing the capsid release-stimulating activity of the Alix protein provide further evidence for a link between capsid formation and autophagy.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Autophagy is an intracellular catabolic process which is required to maintain cellular homeostasis. Pathogen-elicited host cell autophagy may favour containment of infection or may help in bacterial survival. Pathogens have developed the ability to modulate host autophagy. The secreted antigen HP0175, a peptidyl prolyl cis,trans isomerase of Helicobacter pylori has moonlighting functions with reference to host cells. Here we show that it executes autophagy in gastric epithelial cells. Autophagy is dependent on the unfolded protein response (UPR) which activates the expression of PKR-like ER kinase (PERK). This is accompanied by phosphorylation of eIF2-α and transcriptional activation of ATF4 and CHOP. Knockdown of UPR- related genes inhibits the conversion of LC3I to LC3-II, a marker of autophagy. The autophagy- inducing ability of H. pylori is compromised when cells are infected with an isogenic hp0175 mutant. Autophagy precedes apoptosis. Silencing of BECLIN 1 augments cleavage of caspase 3 as well as apoptosis. Increased apoptosis of gastric epithelial cells is known to be linked to H. pylori- mediated gastric inflammation and carcinogenesis. To the best of our knowledge, this study provides the first demonstration of how HP0175, endowed with moonlighting functions, links UPR- dependent autophagy and apoptosis during H. pylori infection.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Vibrio parahaemolyticus is a leading causative agent of seafood-borne gastroenteritis worldwide. Most clinical isolates from patients with diarrhea possess two sets of genes for the type III secretion system (T3SS) on each chromosome (T3SS1 and T3SS2). T3SS is a protein secretion system that delivers effector proteins directly into eukaryotic cells. The injected effectors modify the normal cell functions by altering or disrupting the normal cell signaling pathways. Of the two sets of T3SS genes present in V. parahaemolyticus, T3SS2 is essential for enterotoxicity in several animal models. Recent studies have elucidated the biological activities of several T3SS2 effectors and their roles in virulence. This review focuses on the regulation of T3SS2 gene expression and T3SS2 effectors that specifically target the actin cytoskeleton.
    Cellular Microbiology 12/2014;
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    ABSTRACT: Some of the world's most important diseases are caused by bacterial pathogens that deliver toxic effector proteins directly into eukaryotic cells using type III secretion systems (T3SS). The myriad of pathological outcomes caused by these pathogens is determined, in part, by the manipulation of host cell physiology due to the specific activities of individual effectors among the unique suite each pathogen employs. YspI was found to be an effector, delivered by Yersinia enterocolitica Biovar 1B, that inhibits host cell motility. The action of YspI comes about through its specific interaction with Focal Adhesion Kinase, FAK, which is a fulcrum of focal adhesion complexes for controlling cellular motility. The interaction was defined by a specific domain of YspI that bound to the FAK kinase domain. Further examination revealed that YspI-FAK interaction leads to a reduction of FAK steady-state levels without altering its phosphorylation state. This collection of observations and results showed YspI displays unique functionality by targeting the key regulator of focal adhesion complexes to inhibit cellular movement.
    Cellular Microbiology 11/2014;
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    ABSTRACT: Outbreaks of spring viremia of carp virus (SVCV) in several carp species and other cultivated fish can cause significant mortality and jeopardize the billion-dollar worldwide fish industry. SVCV, also known as Rhabdovirus carpio, is a bullet-shaped RNA virus that enters and amplifies in gill epithelium and later spreads to internal organs. Young fish under stressed conditions (spring cold water, etc.) are more vulnerable to SVCV-induced lethality due to their lack of a mature immune system. Currently, the host response of SVCV remains largely unknown. Here, we observed that autophagy is activated in SVCV-infected epithelioma papulosum cyprinid (EPC) cells. We demonstrated that the SVCV glycoprotein, rather than viral replication, activates the autophagy pathway. In addition, SVCV utilized the autophagy pathway to facilitate its own genomic RNA replication and to enhance its titers in the supernatants. Autophagy promoted the survival of SVCV-infected cells by eliminating damaged mitochondrial DNA generated during viral infection. We further showed that SVCV induces autophagy in EPC cells through the ERK/mTOR signaling pathway. Our results reveal a connection between autophagy and SVCV replication and propose autophagy suppression as a novel means to restrict SVCV viral replication.
    Cellular Microbiology 11/2014;
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    ABSTRACT: Phagocytosis by cells of the innate immune system, such as macrophages, and the subsequent successful maturation of the phagosome, is key for the clearance of pathogens. The fungal pathogen C. neoformans is known to overcome killing by host phagocytes and both replicate within these cells and also escape via a non-lytic process termed vomocytosis. Here we demonstrate that, during intracellular growth, cryptococci modify phagolysosome maturation. Live cryptococci, but not heat-killed pathogens or inert targets, induce the premature removal of the early phagosome markers Rab5 and Rab11. In addition, significant acidification of the phagosome, calcium flux and protease activity are hindered, thus rendering the phagosome permissive for cryptococcal proliferation. Interestingly, several attenuated cryptococcal mutants retain this ability to subvert phagosomal maturation, suggesting that hitherto unidentified pathogen mechanisms regulate this process.
    Cellular Microbiology 11/2014;
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    ABSTRACT: The formation and release of outer membrane vesicles (OMVs) is a phenomenon observed in many bacteria, including Legionella pneumophila. During infection this human pathogen primarily invades alveolar macrophages and replicates within a unique membrane-bound compartment termed Legionella-containing vacuole. In the current study we analyzed the membrane architecture of L. pneumophila OMVs by small-angle X-ray scattering and biophysically characterized OMV membranes. We investigated the interaction of L. pneumophila OMVs with model membranes by Förster resonance energy transfer and Fourier-transform infrared spectroscopy. These experiments demonstrated the incorporation of OMV membrane material into liposomes composed of different eukaryotic phospholipids, revealing an endogenous property of OMVs to fuse with eukaryotic membranes. Cellular co-incubation experiments showed a dose- and time-dependent binding of fluorophore-labeled OMVs to macrophages. Trypan blue quenching experiments disclosed a rapid internalization of OMVs into macrophages at 37°C and 4°C. Purified OMVs induced TNFα production in human macrophages at concentrations starting at 300 ng/ml. Experiments on HEK293-TLR2 and TLR4/MD-2 cell lines demonstrated a dominance of TLR2-dependent signaling pathways. In summary, we demonstrate binding, internalization and biological activity of L. pneumophila OMVs on human macrophages. Our data support OMV membrane fusion as a mechanism for the remote delivery of virulence factors to host cells.
    Cellular Microbiology 11/2014;
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    ABSTRACT: Plasmodium spp., which cause malaria, produce a histamine releasing factor (HRF), an orthologue of mammalian HRF. HRF produced by erythrocytic stages of the parasite is thought to play a role in the pathogenesis of severe malaria. Here, we show in a rodent model that HRF is not important during the erythrocytic but pre-erythrocytic phase of infection, which mainly consists in the transformation in the liver of the mosquito-injected parasite form into the erythrocyte-infecting form. Development of P. berghei ANKA cl15cy1 liver stages lacking HRF is impaired and associated with an early rise in systemic IL-6, a cytokine that strongly suppresses development of Plasmodium liver stages. The defect is rescued by injection of anti-IL-6 antibodies or infection in IL-6-deficient mice and parasite HRF is sufficient to decrease IL-6 synthesis, indicating a direct role of parasite HRF in reducing host IL-6. The target cells modulated by HRF for IL-6 production at early time points during liver infection are neutrophils. Parasite HRF is thus used to down-regulate a cytokine with anti-parasite activity. Our data also highlight the link between a prolonged transition from liver to blood-stage infection and reduced incidence of experimental cerebral malaria (ECM).
    Cellular Microbiology 10/2014;
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    ABSTRACT: Pathogenic Yersinia species evolved a type III secretion system that injects a set of effectors into the host cell cytosol to promote infection. One of these effectors, Yersinia protein kinase A (YpkA), is a multidomain effector that harbors a Ser/Thr kinase domain and a guanine dissociation inhibitor (GDI) domain. The intercellular targets of the kinase and GDI domains of YpkA were identified to be Gαq and the small GTPases RhoA and Rac1, respectively, which synergistically induce cytotoxic effects on infected cells. In this study, we demonstrate that vasodilator-stimulated phosphoprotein (VASP), which is critical for regulation of actin assembly, cell adhesion, and motility is a direct substrate of YpkA kinase activity. Ectopic coexpression of YpkA and VASP in HEK293T cells lead to the phosphorylation of VASP at S157, and YpkA kinase activity is essential for VASP phosphorylation at this site. Moreover, YpkA directly phosphorylates VASP in in vitro kinase assay. YpkA-mediated VASP phosphorylation significantly inhibits actin polymerization and promotes the disruption of actin cytoskeleton, which inhibits the phagocytosis. Taken together, our study found a novel molecular mechanism used by YpkA to disrupt cytoskeleton dynamics, thereby promoting the anti-phagocytosis ability of pathogenic Yersiniae.
    Cellular Microbiology 10/2014;
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    ABSTRACT: Adhesion and invasion of intestinal epithelial cells (IECs) are critical for the pathogenesis of Salmonella Typhi, the etiological agent of human typhoid fever. While Type Three Secretion System-1 (T3SS-1) is a major invasion apparatus of Salmonella, independent invasion mechanisms were described for non-typhoidal Salmonellae. Here we show that T2942, an AIL-like protein of S. Typhi Ty2 strain is required for adhesion and invasion of cultured IECs. That invasion was T3SS-1 independent was proved by ectopic expression of T2942 in the non-invasive E. coli BL21 and double mutant Ty2 (Ty2Δt2942ΔinvG) strains. Laminin and fibronectin were identified as the host binding partners of T2942 with higher affinity for laminin. Standalone function of T2942 was confirmed by cell adhesion of the recombinant protein, while the protein or anti-T2942 antiserum blocked adhesion/ invasion of S. Typhi, indicating specificity. A 20 amino acids extracellular loop was required for invasion, while several loop regions of T2942 contributed to adhesion. Further, T2942 cooperates with laminin-binding T2544 for adhesion and T3SS-1 for invasion. Finally, T2942 was required and synergistically worked with T3SS-1 for pathogenesis of S. Typhi in mice. Considering wide distribution of T2942 among clinical strains, the protein or the 20-mer peptide may be suitable for vaccine development.
    Cellular Microbiology 10/2014;
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    ABSTRACT: SUMOylation, the covalent attachment of a member of the SUMO (small ubiquitin-like modifier) family of proteins to lysines in target substrates, is an essential post-translational modification in eukaryotes. Microbial manipulation of SUMOylation recently emerged as a key virulence strategy for viruses and facultative intracellular bacteria, the latter of which only have been shown to deploy effectors that negatively regulate SUMOylation. Here, we demonstrate that the obligate intracellular bacterium, Anaplasma phagocytophilum, utilizes an effector, AmpA (A. phagocytophilum post-translationally modified protein A) that becomes SUMOylated in host cells and this is important for the pathogen's survival. We previously discovered that AmpA (formerly APH1387) localizes to the A. phagocytophilum-occupied vacuolar membrane (AVM). Algorithmic prediction analyses denoted AmpA as a candidate for SUMOylation. We verified this phenomenon using a SUMO-affinity matrix to precipitate both native AmpA and ectopically expressed green fluorescent protein (GFP)-tagged AmpA. SUMOylation of AmpA was lysine-dependent, as SUMO-affinity beads failed to precipitate a GFP-AmpA protein when its lysine residues were substituted with arginine. Ectopically expressed and endogenous AmpA were poly-SUMOylated, which was consistent with the observation that AmpA colocalizes with SUMO2/3 at the AVM. Only late during the infection cycle did AmpA colocalize with SUMO1, which terminally caps poly-SUMO2/3 chains. AmpA was also detected in the cytosol of infected host cells, further supporting its secretion and likely participation in interactions that aid pathogen survival. Indeed, whereas siRNA-mediated knockdown of Ubc9 – a necessary enzyme for SUMOylation – slightly bolstered A. phagocytophilum infection, pharmacologically inhibiting SUMOylation in infected cells significantly reduced the bacterial load. Ectopically expressed GFP-AmpA served as a competitive agonist against native AmpA in infected cells, while lysine-deficient GFP-AmpA was less effective, implying that modification of AmpA lysines is important for infection. Collectively, these data show that AmpA becomes directly SUMOylated during infection, representing a novel tactic for A. phagocytophilum survival.
    Cellular Microbiology 10/2014;