Lipid Exchange between Borrelia burgdorferi and Host Cells

Borrelia burgdorferi, the agent of Lyme disease, has cholesterol and cholesterol-glycolipids that are essential for bacterial fitness, are antigenic, and could be important in mediating interactions with cells of the eukaryotic host. We show that the spirochetes can acquire cholesterol from plasma membranes of epithelial cells. In addition, through fluorescent and confocal microscopy combined with biochemical approaches, we demonstrated that B. burgdorferi labeled with the fluorescent cholesterol analog BODIPY-cholesterol or 3H-labeled cholesterol transfer both cholesterol and cholesterol-glycolipids to HeLa cells. The transfer occurs through two different mechanisms, by direct contact between the bacteria and eukaryotic cell and/or through release of outer membrane vesicles. Thus, two-way lipid exchange between spirochetes and host cells can occur. This lipid exchange could be an important process that contributes to the pathogenesis of Lyme disease

Evidence That Two ATP-Dependent (Lon) Proteases in Borrelia burgdorferi Serve Different Functions

The canonical ATP-dependent protease Lon participates in an assortment of biological processes in bacteria, including the catalysis of damaged or senescent proteins and short-lived regulatory proteins. Borrelia spirochetes are unusual in that they code for two putative ATP-dependent Lon homologs, Lon-1 and Lon-2. Borrelia burgdorferi, the etiologic agent of Lyme disease, is transmitted through the blood feeding of Ixodes ticks. Previous work in our laboratory reported that B. burgdorferi lon-1 is upregulated transcriptionally by exposure to blood in vitro, while lon-2 is not. Because blood induction of Lon-1 may be of importance in the regulation of virulence factors critical for spirochete transmission, the clarification of functional roles for these two proteases in B. burgdorferi was the object of this study. On the chromosome, lon-2 is immediately downstream of ATP-dependent proteases clpP and clpX, an arrangement identical to that of lon of Escherichia coli. Phylogenetic analysis revealed that Lon-1 and Lon-2 cluster separately due to differences in the NH2-terminal substrate binding domains that may reflect differences in substrate specificity. Recombinant Lon-1 manifested properties of an ATP-dependent chaperone-protease in vitro but did not complement an E. coli Lon mutant, while Lon-2 corrected two characteristic Lon-mutant phenotypes. We conclude that B. burgdorferi Lons -1 and -2 have distinct functional roles. Lon-2 functions in a manner consistent with canonical Lon, engaged in cellular homeostasis. Lon-1, by virtue of its blood induction, and as a unique feature of the Borreliae, may be important in host adaptation from the arthropod to a warm-blooded host

O Memorial de Imigração Polonesa em Curitiba: dinâmicas culturais e interesses políticos no âmbito memoralista

Neste artigo, analisa-se o conceito de memorial, considerando as atuais definições de Museu propostas pelo Conselho Internacional de Museus e pelo Instituto Brasileiro de Museus, tendo como objeto de investigação o Memorial de Imigração Polonesa de Curitiba. Evidenciam-se a importância e a complexidade no trato com o patrimônio e as dificuldades de pensá-lo a partir dos sujeitos e das referências culturais de determinado grupo em contraponto aos interesses políticos e econômicos; no caso em questão, voltadas às necessidades da política de city marketing como estratégia de construção da imagem da cidade. Para tanto, foram considerados os perfis de atuação dos memoriais em diferentes partes do mundo, na tentativa de delimitação conceitual, exemplificando-se a pluralidade de temas e formatos dessas instituições no âmbito nacional e global. As discussões levantadas permitem pensar que os Museus Memoriais desempenham as atividades de um memorial no âmbito museológico, confirmando a ambivalência dessas duas instituições e sua interface privilegiada com o poder político.This article analyzes the memorial concept, considering the Museum definition presented by the International Council of Museums and the Brazilian Institute of Museums. The aim of this study was the Curitiba Polish Immigration Memorial. It highlights the importance and complexity in dealing with the heritage and the difficulties of thinking it from the individuals and the cultural references of certain groups as opposed to political and economic interests; in this case the needs of the city marketing policy as city image building strategy. Therefore, the memorials performance profiles in different parts of the world in an attempt to conceptual definition, exemplifying the diversity of themes and formats of these institutions at the national and global levels. The discussions show that it is possible to consider that the Memorials Museums perform the same activities of a memorial within the museological context, confirming the ambivalence of these two institutions and prime interface with political power

The Urokinase Receptor Can Be Induced by Borrelia burgdorferi through Receptors of the Innate Immune System

Monocytic cells exposed to Borrelia burgdorferi, through unknown receptors, overexpress the urokinase receptor (uPAR), a key mediator of the plasminogen activation system. We show that combined blockade of CD14 and TLR2 causes a significant inhibition of B. burgdorferi-induced uPAR in Mono Mac 6 (MM6) cells. Other pattern recognition receptors tested (CD11b/CD18, the mannose receptor, and the N-formyl-methionyl-leucyl-phenylalanine receptor) did not have demonstrated roles in B. burgdorferi-mediated uPAR induction. We dissected the result for CD14 andTLR2 by investigating the singular contributions of each. Independent functional blockade of CD14 or TLR2 failed to inhibit B. burgdorferi-mediated uPAR induction. 1,25-Dihydroxyvitamin D(3) differentiation of MM6 cells increased CD14 expression 12-fold but did not augment B. burgdorferi-mediated uPAR expression. Peritoneal exudate macrophages (PEM) from CD14- or TLR2-deficient mice were not defective in B. burgdorferi-mediated synthesis of uPAR mRNA and protein. Increased uPAR mRNA or protein or both were apparent in PEM from transgenic and control mice, even at a ratio of one Borrelia spirochete per cell. We conclude that signaling for the uPAR response, as mediated by B. burgdorferi, proceeds with CD14 and TLR2 as partial contributors. That part under control of CD14 and TLR2 represents a new link between the host plasminogen activation and innate immunity systems

Discovery of the Lyme Disease Agent.

A detailed first-hand account of the events leading up to the discovery of the Lyme disease agent has been lacking. Nearly 40 years have elapsed since the discovery of the organism that was named Borrelia burgdorferi There are thousands of articles in the scientific and medical literature on this organism and the disease that it causes. In the interval since the organism's discovery, however, misconceptions have arisen regarding not only the disease but the discovery itself. Accordingly, with this paper, we aim to fill in the details of this episode in medical history with a joint introduction, first-person accounts by the two authors, a summary of contemporaneous events, and concluding comments. The history of the discovery of the Lyme disease agent has threads originating in different places in the United States. Studies on Long Island, NY, provided the epidemiological thread of studies on rickettsial diseases and babesiosis, linking the latter with the cutaneous manifestation of Lyme disease, now known as erythema migrans. The Long Island thread intersected Montana's Rocky Mountain Laboratories thread of studies on a relapsing fever Borrelia and its cultivation and expertise in vector biology. This intersection made possible the discovery of the spirochete and its recovery from patients. This paper stresses that what may seem to have been an individual scientific discovery is actually the product of several threads coming together and is attributable to more people than appreciated

The Fur Homologue in Borrelia burgdorferi

Borrelia burgdorferi contains a gene that codes for a Fur homologue. The function of this Fur protein is unknown; however, spirochetes grown at 23 or 35°C expressed fur as determined by reverse transcriptase PCR. The fur gene (BB0647) was cloned and overexpressed as a His-Fur fusion protein in Escherichia coli. The fusion protein was purified by zinc-chelate chromatography, and the N-terminal His tag was removed to generate recombinant Fur for use in mobility shift studies. Fur bound DNA containing the E. coli Fur box sequence (GATAATGATAATCATTATC) or Bacillus subtilis Per box sequence (TTATAAT-ATTATAA) with an apparent K(d) of ∼20 nM. Fur also bound the upstream sequences of three Borrelia genes: BB0646 (gene encoding a hydrolase of the α/β-fold family), BB0647 (fur), and BB0690 (napA). Addition of metal ions was not required. Binding activity was greatly decreased by either exposure to oxidizing agents (H(2)O(2), t-butyl hydroperoxide, cumene hydroperoxide, or diamide) or by addition of Zn(2+). B. burgdorferi NapA is a homologue of Dps. Dps functions in E. coli to protect DNA against damage during periods of redox stress. Fur may function in B. burgdorferi as a repressor and regulate oxidative stress genes. Additional genes (10 chromosomal and 15 plasmid) that may be Fur regulated were identified by in silico analysis

Presence of Pili on the Surface of Francisella tularensis

Francisella tularensis is a highly infectious gram-negative bacterium with potential for use as a bioweapon. Analysis of the F. tularensis live vaccine strain (LVS) ultrastructure by electron microscopy revealed the presence of long, thin fibers, similar in appearance to type 4 pili. The highly virulent F. tularensis Schu S4 strain was found to contain type 4 pilus genes, and we confirmed that these genes are present and expressed in the LVS