Borrelia burgdorferi BBK32 Inhibits the Classical Pathway by Blocking Activation of the C1 Complement Complex

Citation: Garcia, B. L., Zhi, H., Wager, B., Hook, M., & Skare, J. T. (2016). Borrelia burgdorferi BBK32 Inhibits the Classical Pathway by Blocking Activation of the C1 Complement Complex. Plos Pathogens, 12(1), 28. doi:10.1371/journal.ppat.1005404Pathogens that traffic in blood, lymphatics, or interstitial fluids must adopt strategies to evade innate immune defenses, notably the complement system. Through recruitment of host regulators of complement to their surface, many pathogens are able to escape complement-mediated attack. The Lyme disease spirochete, Borrelia burgdorferi, produces a number of surface proteins that bind to factor H related molecules, which function as the dominant negative regulator of the alternative pathway of complement. Relatively less is known about how B. burgdorferi evades the classical pathway of complement despite the observation that some sensu lato strains are sensitive to classical pathway activation. Here we report that the borrelial lipoprotein BBK32 potently and specifically inhibits the classical pathway by binding with high affinity to the initiating C1 complex of complement. In addition, B. burgdorferi cells that produce BBK32 on their surface bind to both C1 and C1r and a serum sensitive derivative of B. burgdorferi is protected from killing via the classical pathway in a BBK32-dependent manner. Subsequent biochemical and biophysical approaches localized the anti-complement activity of BBK32 to its globular C-terminal domain. Mechanistic studies reveal that BBK32 acts by entrapping C1 in its zymogen form by binding and inhibiting the C1 subcomponent, C1r, which serves as the initiating serine protease of the classical pathway. To our knowledge this is the first report of a spirochetal protein acting as a direct inhibitor of the classical pathway and is the only example of a biomolecule capable of specifically and noncovalently inhibiting C1/C1r. By identifying a unique mode of complement evasion this study greatly enhances our understanding of how pathogens subvert and potentially manipulate host innate immune systems

Identification of a novel transport system in Borrelia burgdorferi that links the inner and outer membranes

Borrelia burgdorferi, the spirochete that causes Lyme disease, is a diderm organism that is similar to Gram-negative organisms in that it contains both an inner and outer membrane. Unlike typical Gram-negative organisms, however, B. burgdorferi lacks lipopolysaccharide (LPS). Using computational genome analyses and structural modeling, we identified a transport system containing six proteins in B. burgdorferi that are all orthologs to proteins found in the lipopolysaccharide transport (LPT) system that links the inner and outer membranes of Gram-negative organisms and is responsible for placing LPS on the surface of these organisms. While B. burgdorferi does not contain LPS, it does encode over 100 different surface-exposed lipoproteins and several major glycolipids, which like LPS are also highly amphiphilic molecules, though no system to transport these molecules to the borrelial surface is known. Accordingly, experiments supplemented by molecular modeling were undertaken to determine whether the orthologous LPT system identified in B. burgdorferi could transport lipoproteins and/or glycolipids to the borrelial outer membrane. Our combined observations strongly suggest that the LPT transport system does not transport lipoproteins to the surface. Molecular dynamic modeling, however, suggests that the borrelial LPT system could transport borrelial glycolipids to the outer membrane

Devastating Rio Doce mining disaster sends shockwaves through earthworm populations.

The Fundão dam breach is considered one of the most severe environmental mining disasters globally, causing widespread changes to the soils of the Rio Doce watershed, one of Brazil’s most important catchments. Given the ecological importance of earthworms to soil structure and dynamics, we investigated the richness, abundance, and biomass of both native and invasive earthworm species in riparian zones along the Rio Doce to understand their responses to the altered soil conditions. Sampling was conducted in reference and impacted sites across five municipalities in Minas Gerais: Mariana, Rio Casca, Ipatinga, Conselheiro Pena, and Aimorés. We identified eight species - two invasive (Amynthas gracilis and Pontoscolex corethrurus) and six native (two Rhinodrilus, three Righiodrilus, including at least two undescribed species, and one Ocnerodrilidae species)—with native biomass approximately five times lower in impacted sites compared to reference sites. Furthermore, the new tailings environment altered the relationships between soil properties and earthworm abundance for both native and invasive species. These findings indicate that native earthworms are less tolerant of the disturbed soil conditions than invasive species, which may contribute to shifts in community composition. The disruption of soil-fauna interactions underscores the long-term ecological consequences of mining-related disturbances and highlights the need for restoration efforts that consider belowground biodiversity.On line first

Dise?o, construcci?n y equipamiento de un centro de informaci?n para la investigaci?n en la Facultad de Ingenier?a Civil de la Universidad Nacional de Ingenier?a

La facultad de ingenier?a civil de la universidad nacional de ingenier?a, busca promover la investigaci?n en sus alumnos tanto de pregrado como de postgrado, motivo por el que se tuvo la iniciativa de contar con una infraestructura adicional cuya funci?n ser? de un centro de informaci?n e investigaci?n. El presente estudio tiene como objetivo desarrollar los planes de gesti?n de una infraestructura que se integre a la infraestructura existente, que sea duradero y que permita el desarrollo de la investigaci?n de los estudiantes, que cumpla con los requisitos del proyecto y satisfaga las expectativas del cliente. Esta construcci?n tendr? la particularidad que en sus bases se coloquen aisladores s?smicos, es preciso resaltar que este edificio es el primero en una universidad p?blica en el Per? al que se le va a instalar aisladores s?smicos; adem?s, ser? sostenible con la implementaci?n de un techo verde en su ?ltimo nivel Este edificio tendr? los servicios necesarios de acuerdo a lo solicitado por el cliente (UNI) sin que la realizaci?n del proyecto pueda afectar las actividades acad?micas que desarrolla. Por ende, en el presente trabajo ha sido importante identificar, evaluar y aplicar los planes de acciones respectivos a los ?stakeholders? del proyecto

Nutrient Dynamics and Recovery Potential in the Tukad Badung River, Indonesia

This study explores the spatiotemporal variations in nitrogen and phosphorus pollutants in the Tukad Badung River, an essential water source for Bali’s communities, increasingly impacted by agricultural, domestic, and industrial discharges. Bi-daily sampling at six strategically selected sites along the river’s 18-kilometer stretch revealed substantial fluctuations in water quality, with downstream sites consistently exhibiting elevated pollutant concentrations. Ammonia concentrations varied from 1.5 to 4.2 mg.L-1, nitrate levels ranged from 5.0 to 11.6 mg.L-1, and total phosphorus concentrations spanned 0.5 to 2.5 mg.L-1, all of which were highest during afternoon sampling, likely due to reduced flow and increased anthropogenic inputs. Total suspended solids (TSS) exhibited temporal and spatial variability, ranging from 80 to 127 mg.L-1, with the highest concentrations observed at midstream sites, suggesting localized sedimentation from human activities. The nutrient dynamics displayed marked temporal variations, with concentrations rising during afternoon hours, reflecting shifts in human activity and changes in river flow conditions. Furthermore, the study assessed nutrient recovery technologies, such as precipitation and adsorption, which were able to recover up to 80% of extractable nutrients. These findings not only characterize the pollution trends but also highlight the potential of nutrient recovery techniques in reducing dependency on synthetic fertilizers. This research emphasizes the need for integrated watershed management and adaptive recovery strategies to mitigate nutrient pollution and enhance the sustainability of river ecosystems for future generations

Mining tailings severely impact plant communities in a rainforest watershed.

The collapse of a mining tailings dam in 2015 drastically affected a large area of an already threatened Atlantic Forest along the Rio Doce in Brazil. We evaluated the interactions between edaphic and floristic factors in impacted and reference sites to understand how the impact of the tailings affected the riparian plant communities along the river. The species richness of the adult and sapling strata was, respectively, 46.4 % and 61.5 % lower in the impacted sites relative to the reference sites. A similar pattern was observed for both species and phyloge netic diversity. We also recorded large changes in species composition in the adult and sapling strata in impacted sites relative to the reference sites along the river. These negative changes in the plant community were correlated with drastic increases in soil iron and phosphorus concentration, and fine sand proportion, and de creases in the proportion of carbon and coarse sand in the sites impacted by the mining tailings. We observed a close relationship between plant composition in both the adult and sapling strata with edaphic factors. The al terations in species composition triggered by the deposition of mining tailings may induce significant shifts in ecosystems, potentially prompting numerous tipping points throughout the river basin, as indicated by the different sapling species, some of which are invasive species of highly difficult eradication. These altered forests might suffer from impoverishment, dominated by a limited species set, some of which could expand its distri bution upon neighboring, already threatened, regions. Such expansion could exacerbate the degradation of the Rio Doce watershed to a point of no return to the previous condition

Immunization with a Borrelia burgdorferi BB0172-Derived Peptide Protects Mice against Lyme Disease

Lyme disease is the most prevalent arthropod borne disease in the US and it is caused by the bacterial spirochete Borrelia burgdorferi (Bb), which is acquired through the bite of an infected Ixodes tick. Vaccine development efforts focused on the von Willebrand factor A domain of the borrelial protein BB0172 from which four peptides (A, B, C and D) were synthesized and conjugated to Keyhole Limpet Hemocyanin, formulated in Titer Max® adjuvant and used to immunize C3H/HeN mice subcutaneously at days 0, 14 and 21. Sera were collected to evaluate antibody responses and some mice were sacrificed for histopathology to evaluate vaccine safety. Twenty-eight days post-priming, protection was evaluated by needle inoculation of half the mice in each group with 103 Bb/mouse, whereas the rest were challenged with 105Bb/mouse. Eight weeks post-priming, another four groups of similarly immunized mice were challenged using infected ticks. In both experiments, twenty-one days post-challenge, the mice were sacrificed to determine antibody responses, bacterial burdens and conduct histopathology. Results showed that only mice immunized with peptide B were protected against challenge with Bb. In addition, compared to the other the treatment groups, peptide B-immunized mice showed very limited inflammation in the heart and joint tissues. Peptide B-specific antibody titers peaked at 8 weeks post-priming and surprisingly, the anti-peptide B antibodies did not cross-react with Bb lysates. These findings strongly suggest that peptide B is a promising candidate for the development of a new DIVA vaccine (Differentiate between Infected and Vaccinated Animals) for protection against Lyme disease.The open access fee for this work was funded through the Texas A&M University Open Access to Knowledge (OAK) Fund

A unified model for BAM function that takes into account type Vc secretion and species differences in BAM composition

Transmembrane proteins in the outer membrane of Gram-negative bacteria are almost exclusively β-barrels. They are inserted into the outer membrane by a conserved and essential protein complex called the BAM (for β-barrel assembly machinery). In this commentary, we summarize current research into the mechanism of this protein complex and how it relates to type V secretion. Type V secretion systems are autotransporters that all contain a β-barrel transmembrane domain inserted by BAM. In type Vc systems, this domain is a homotrimer. We argue that none of the current models are sufficient to explain BAM function particularly regarding type Vc secretion. We also find that current models based on the well-studied model system Escherichia coli mostly ignore the pronounced differences in BAM composition between different bacterial species. We propose a more holistic view on how all OMPs, including autotransporters, are incorporated into the lipid bilayer