BB0324 and BB0028 are constituents of the Borrelia burgdorferi β-barrel assembly machine (BAM) complex

<p>Abstract</p> <p>Background</p> <p>Similar to Gram-negative bacteria, the outer membrane (OM) of the pathogenic spirochete, <it>Borrelia burgdorferi</it>, contains integral OM-spanning proteins (OMPs), as well as membrane-anchored lipoproteins. Although the mechanism of OMP biogenesis is still not well-understood, recent studies have indicated that a heterooligomeric OM protein complex, known as BAM (β-barrel assembly machine) is required for proper assembly of OMPs into the bacterial OM. We previously identified and characterized the essential β-barrel OMP component of this complex in <it>B. burgdorferi</it>, which we determined to be a functional BamA ortholog.</p> <p>Results</p> <p>In the current study, we report on the identification of two additional protein components of the <it>B. burgdorferi </it>BAM complex, which were identified as putative lipoproteins encoded by ORFs BB0324 and BB0028. Biochemical assays with a BamA-depleted <it>B. burgdorferi </it>strain indicate that BB0324 and BB0028 do not readily interact with the BAM complex without the presence of BamA, suggesting that the individual <it>B. burgdorferi </it>BAM components may associate only when forming a functional BAM complex. Cellular localization assays indicate that BB0324 and BB0028 are OM-associated subsurface lipoproteins, and <it>in silico </it>analyses indicate that BB0324 is a putative BamD ortholog.</p> <p>Conclusions</p> <p>The combined data suggest that the BAM complex of <it>B. burgdorferi </it>contains unique protein constituents which differ from those found in other proteobacterial BAM complexes. The novel findings now allow for the <it>B. burgdorferi </it>BAM complex to be further studied as a model system to better our understanding of spirochetal OM biogenesis in general.</p

Composition and Corrosivity of Extracellular Polymeric Substances from the Hydrocarbon-Degrading Sulfate-Reducing Bacterium Desulfoglaeba alkanexedens ALDC

Sulfate-reducing bacteria (SRB) often exist as cell aggregates and in biofilms surrounded by a matrix of extracellular polymeric substances (EPSs). The chemical composition of EPSs may facilitate hydrophobic substrate biodegradation and promote microbial influenced corrosion (MIC). Although EPSs from non-hydrocarbon-degrading SRB have been studied; the chemical composition of EPSs from hydrocarbon-degrading SRBs has not been reported. The isolated EPSs from the sulfate-reducing alkane-degrading bacterium Desulfoglaeba alkanexedens ALDC was characterized with scanning and fluorescent microscopy, nuclear magnetic resonance spectroscopy (NMR), and by colorimetric chemical assays. Specific fluorescent staining and 1H NMR spectroscopy revealed that the fundamental chemical structure of the EPS produced by D. alkanexedens is composed of pyranose polysaccharide and cyclopentanone in a 2:1 ratio. NMR analyses indicated that the pyranose ring structure is bonded by 1,4 connections with the cyclopentanone directly bonded to one pyranose ring. The presence of cyclopentanone presumably increases the hydrophobicity of the EPS that may facilitate the accessibility of hydrocarbon substrates to aggregating cells or cells in a biofilm. Weight loss and iron dissolution experiments demonstrated that the EPS did not contribute to the corrosivity of D. alkanexedens cells

Characterization of Unique Regions of Borrelia burgdorferi Surface-Located Membrane Protein 1 ▿ † ‡

The pathogen of Lyme disease, Borrelia burgdorferi, produces a putative surface protein termed “surface-located membrane protein 1” (Lmp1). Lmp1 has been shown previously to assist the microbe in evasion of host-acquired immune defenses and in the establishment of persistent infection of mammals. Here, we show that Lmp1 is an integral membrane protein with surface-exposed N-terminal, middle, and C-terminal regions. During murine infection, antibodies recognizing these three protein regions were produced. Separate immunization of mice with each of the discrete regions exerted differential effects on spirochete survival during infection. Notably, antibodies against the C-terminal region primarily interfered with B. burgdorferi persistence in the joints, while antibodies specific to the N-terminal region predominantly affected pathogen levels in the heart, including the development of carditis. Genetic reconstitution of lmp1 deletion mutants with the lmp1 N-terminal region significantly enhanced its ability to resist the bactericidal effects of immune sera and also was observed to increase pathogen survival in vivo. Taken together, the combined data suggest that the N-terminal region of Lmp1 plays a distinct role in spirochete survival and other parts of the protein are related to specific functions corresponding to pathogen persistence and tropism during infection that is displayed in an organ-specific manner. The findings reported here underscore the fact that surface-exposed regions of Lmp1 could potentially serve as vaccine targets or antigenic regions that could alter the course of natural Lyme disease

HIV-Positive Youth's Perspectives on the Internet and eHealth

BACKGROUND: Globally, half of all new HIV infections occur among young people. Despite this incidence, there is a profound lack of resources for HIV-positive youth. OBJECTIVE: To investigate Internet access, use and acceptability as a means for health promotion and health service delivery among HIV-positive youth. METHODS: A community-based participatory approach was used to conduct a mixed methods research study. Thirty-five qualitative in-depth semi-structured interviews were conducted with youth (ages 12-24) living with HIV in Ontario. Also, brief structured demographic surveys were administered at the time of the interview. A stakeholder group of youth living with HIV, professionals and researchers collaboratively analyzed the data for emerging themes. RESULTS: Five main themes were identified with respect to the youth's use of and interest in the Internet as a health promotion strategy. These include: (1) high rates of Internet use and access; (2) issues around public and private terminals; (3) their use of the Internet primarily for communication and entertainment; (4) the rarity of health information seeking behavior in this group; and (5) wanting "one-stop shopping" from an e-health site. HIV-positive youth were enthusiastic about the possibility of content that was developed specifically to target them and their needs. Also, they were keen about the possibilities for increased social support that youth-specific online chat rooms and message boards might provide. CONCLUSION: Given high rates of use, access and interest, the Internet provides an important way to reach young people living with HIV using health services and health promotion programs. The onus is on e-Health developers to understand the particular needs of HIV-positive youth and create relevant content