Identification of Lysine Residues in the Borrelia burgdorferi DbpA Adhesin Required for Murine Infection

Fortune, Danielle E.; Lin, Yi Pin; Deka, Ranjit K.; Groshong, Ashley M.; Moore, Brendan P.; Hagman, Kayla E.; Leong, John M.; Tomchick, Diana R.; Blevins, Jon S.

doi:10.1128/iai.02036-14

Cited by 25 publications

(45 citation statements)

References 82 publications

(112 reference statements)

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“…6C). This finding prompted us to assess transcript levels for ospC and dbpA, two RpoS-dependent genes that function exclusively within the mammal (19,66,(108)(109)(110)(111)(112) and whose expression is unaffected by c-di-GMP (see Fig. S3 in the supplemental material).…”

Section: Resultsmentioning

confidence: 99%

Cyclic di-GMP Modulates Gene Expression in Lyme Disease Spirochetes at the Tick-Mammal Interface To Promote Spirochete Survival during the Blood Meal and Tick-to-Mammal Transmission

et al. 2015

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e Borrelia burgdorferi, the Lyme disease spirochete, couples environmental sensing and gene regulation primarily via the Hk1/ Rrp1 two-component system (TCS) and Rrp2/RpoN/RpoS pathways. Beginning with acquisition, we reevaluated the contribution of these pathways to spirochete survival and gene regulation throughout the enzootic cycle. Live imaging of B. burgdorferi caught in the act of being acquired revealed that the absence of RpoS and the consequent derepression of tick-phase genes impart a Stay signal required for midgut colonization. In addition to the behavioral changes brought on by the RpoS-off state, acquisition requires activation of cyclic di-GMP (c-di-GMP) synthesis by the Hk1/Rrp1 TCS; B. burgdorferi lacking either component is destroyed during the blood meal. Prior studies attributed this dramatic phenotype to a metabolic lesion stemming from reduced glycerol uptake and utilization. In a head-to-head comparison, however, the B. burgdorferi ⌬glp mutant had a markedly greater capacity to survive tick feeding than B. burgdorferi ⌬hk1 or ⌬rrp1 mutants, establishing unequivocally that glycerol metabolism is only one component of the protection afforded by c-di-GMP. Data presented herein suggest that the protective response mediated by c-di-GMP is multifactorial, involving chemotactic responses, utilization of alternate substrates for energy generation and intermediary metabolism, and remodeling of the cell envelope as a means of defending spirochetes against threats engendered during the blood meal. Expression profiling of c-di-GMP-regulated genes through the enzootic cycle supports our contention that the Hk1/Rrp1 TCS functions primarily, if not exclusively, in ticks. These data also raise the possibility that c-di-GMP enhances the expression of a subset of RpoS-dependent genes during nymphal transmission. Borrelia burgdorferi, the causative agent of Lyme disease, is maintained in nature within an enzootic cycle that involves an arthropod vector and vertebrate reservoir hosts, typically, small rodents and birds (1). In the northeastern United States, the primary vector for B. burgdorferi is the black-legged deer tick, Ixodes scapularis (2, 3). Because B. burgdorferi cannot be passaged transovarially, naive larvae acquire spirochetes by feeding on infected reservoir hosts. Successful colonization of the vector requires B. burgdorferi to establish an intimate association with rapidly differentiating, highly endocytic midgut epithelial cells (4-6). In order to accomplish this feat, spirochetes must resist deleterious substances within the midgut lumen, such as host-and tick-derived innate immune effector molecules, reactive oxygen species (ROS), and salivary enzymes imbibed from the feeding site (4, 7-11). At the same time, B. burgdorferi also must alter its metabolic machinery to exploit the availability of alternative carbon sources (e.g., glycerol, N-acetylglucosamine [GlcNAc], chitobiose) as the supply of ingested glucose diminishes (12-15). During nymphal transmission, spirochetes are almost certai...

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Section: Resultsmentioning

confidence: 99%

Cyclic di-GMP Modulates Gene Expression in Lyme Disease Spirochetes at the Tick-Mammal Interface To Promote Spirochete Survival during the Blood Meal and Tick-to-Mammal Transmission

et al. 2015

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“…This basic patch, which contains three lysine residues (K82, K163 and K170 in B31 DBPA; K85, K166 and K173 in N40 DBPA) known to be crucial to GAG binding, has also been identified as the primary site for DBPA-GAG interactions in both B31 and 297 DBPAs. [13,14,16] It is notable that the linker in N40 and B31 DBPAs almost entirely obscures this basic pocket. However, the helical nature of the linker in PBr results in a more exposed basic patch than in B31 and N40 DBPAs ( Figure 5).…”

Section: Structural Differences Among Dbpas Of Strains B31 N40 and Pbrmentioning

confidence: 99%

“…[9] The crystal structure of DBPA from strain 297 adopts an identical fold [16]. Building on these investigations, we have determined the solution structures of DBPA from strain N40 of Borrelia burgdorferi and strain PBr of Borrelia gariini, two variants that have significantly different GAG affinities than B31 DBPA.…”

Section: Structural Differences Among Dbpas Of Strains B31 N40 and Pbrmentioning

confidence: 99%

“…[9,14,16] To further understand the correlation of DBPA sequence variation with differences in GAG affinities, we have determined the solution structures for N40 and PBr strains of DBPA, and analyzed the interactions of these proteins with GAG ligands. The structures of both proteins retain the five helical bundle fold of B31 DBPA, with the N40 DBPA structure being almost identical to that of B31 DBPA.…”

Section: Introductionmentioning

confidence: 99%

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Structural mechanisms underlying sequence-dependent variations in GAG affinities of decorin binding protein A, a Borrelia burgdorferi adhesin

Morgan

Wang

2015

Biochemical Journal

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Abbreviations: DBPA, decorin-binding protein A. DBPB, decorin-binding protein B. GAG, glycosaminoglycan. DS, dermatan sulfate. HSQC, heteronuclear single quantum coherence spectroscopy.Summary statement: Structural mechanisms behind variations in GAG affinities of DBPAs from different Borrelia strains were investigated using NMR. DBPA from strain PBr was revealed to have an additional GAG-binding epitope and a retracted linker allowing more access to its GAG-binding sites. AbstractDecorin binding protein A (DBPA) is an important surface adhesin of the bacterium Borrelia burgdorferi, the causative agent of Lyme disease. DBPA facilitates the bacteria's colonization of human tissue by adhering to glycosaminoglycan (GAG), a sulfated polysaccharide. Interestingly, DBPA sequence variation among different strains of Borrelia spirochetes is high, resulting in significant differences in their GAG affinities. However, the structural mechanisms contributing to these differences are unknown. We determined the solution structures of DBPAs from strain N40 of Borrelia burgdorferi and strain PBr of Borrelia gariini, two DBPA variants whose GAG affinities deviate significantly from strain B31, the best characterized version of DBPA. Our structures revealed that significant differences exist between PBr DBPA and B31/N40 DBPAs. In particular, the C-terminus of PBr DBPA, unlike C-termini from B31 and N40 DBPAs, is positioned away from the GAG-binding pocket, and the linker between helices one and two of PBr DBPA is highly structured and retracted from the GAGbinding pocket. The repositioning of the C-terminus allowed the formation of an extra GAGbinding epitope in PBr DBPA, and the retracted linker give GAG ligands more access to the GAG-binding epitopes than other DBPAs. Characterization of GAG ligands' interactions with wild type PBr and mutants confirmed the importance of the second major GAG-binding epitope and established the fact that the two epitopes are independent of one another and the new epitope is as important to GAG binding as the traditional epitope.

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“…The attachment of B. burgdorferi to the host ECM is likely critical for pathogenesis and persistence in mammals. Indeed, for many of these adhesins, deletion mutants have significant defects in infectivity, fail to disseminate widely in the host, or have other effects on disease, such as alterations in the severity of arthritis (24)(25)(26)(27).…”

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confidence: 99%

Borrelia burgdorferi RevA Significantly Affects Pathogenicity and Host Response in the Mouse Model of Lyme Disease

et al. 2015

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The Lyme disease spirochete, Borrelia burgdorferi, expresses RevA and numerous outer surface lipoproteins during mammalian infection. As an adhesin that promotes bacterial interaction with fibronectin, RevA is poised to interact with the extracellular matrix of the host. To further define the role(s) of RevA during mammalian infection, we created a mutant that is unable to produce RevA. The mutant was still infectious to mice, although it was significantly less well able to infect cardiac tissues. Complementation of the mutant with a wild-type revA gene restored heart infectivity to wild-type levels. Additionally, revA mutants led to increased evidence of arthritis, with increased fibrotic collagen deposition in tibiotarsal joints. The mutants also induced increased levels of the chemokine CCL2, a monocyte chemoattractant, in serum, and this increase was abolished in the complemented strain. Therefore, while revA is not absolutely essential for infection, deletion of revA had distinct effects on dissemination, arthritis severity, and host response. Borrelia burgdorferi, the causative agent of Lyme disease, is a vector-borne pathogen that successfully colonizes both ticks and a variety of vertebrate hosts. In mammals, B. burgdorferi is frequently found associated with connective tissues (1-13), and the bacterium is often detected in cartilaginous or collagen-rich tissues, such as skin and joints (6,7,9,(11)(12)(13)(14)(15)(16)(17)(18). Adhesins expressed by B. burgdorferi facilitate interactions with these tissues. B. burgdorferi expresses a plethora of outer surface proteins that interact with numerous components of the extracellular matrix (ECM), such as fibronectin, decorin, and integrins (19-23). The attachment of B. burgdorferi to the host ECM is likely critical for pathogenesis and persistence in mammals. Indeed, for many of these adhesins, deletion mutants have significant defects in infectivity, fail to disseminate widely in the host, or have other effects on disease, such as alterations in the severity of arthritis (24-27).The interactions of B. burgdorferi with fibronectin are facilitated by several distinct bacterial surface proteins, including BBK32, RevA, BB0347, and CspA (BbCRASP-1) (28-31). The redundancy in adhesins makes it difficult to dissect the role of each B. burgdorferi fibronectin binding protein in the pathogenesis of Lyme disease. For example, real-time microscopic imaging in live mice revealed a significant role for BBK32 in interactions with host vasculature, yet bbk32 mutants are still able to infect mammals (32).RevA is a 19-kDa surface protein encoded on the circular plasmid 32 (cp32) family of plasmids (33). RevA expression is elevated during mammalian infection over its expression in the tick vector, suggesting a role in pathogenesis (30,(34)(35)(36). RevA binds to fibronectin, and anti-RevA antibodies block the binding of whole B. burgdorferi bacteria to fibronectin (30). RevA is antigenic, as evidenced by the fact that both mice and human Lyme disease patients produce antibodies...

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Identification of Lysine Residues in the Borrelia burgdorferi DbpA Adhesin Required for Murine Infection

Cited by 25 publications

References 82 publications

Cyclic di-GMP Modulates Gene Expression in Lyme Disease Spirochetes at the Tick-Mammal Interface To Promote Spirochete Survival during the Blood Meal and Tick-to-Mammal Transmission

Cyclic di-GMP Modulates Gene Expression in Lyme Disease Spirochetes at the Tick-Mammal Interface To Promote Spirochete Survival during the Blood Meal and Tick-to-Mammal Transmission

Structural mechanisms underlying sequence-dependent variations in GAG affinities of decorin binding protein A, a Borrelia burgdorferi adhesin

Borrelia burgdorferi RevA Significantly Affects Pathogenicity and Host Response in the Mouse Model of Lyme Disease

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