Artificial regulation of <i>ospC</i> expression in <i>Borrelia burgdorferi</i>

Gilbert, Michael A.; Morton, Elizabeth A.; Bundle, Sharyl F.; Samuels, D. Scott

doi:10.1111/j.1365-2958.2007.05593.x

Cited by 71 publications

(131 citation statements)

References 69 publications

Supporting

Mentioning

127

Contrasting

Order By: Relevance

“…However, nothing is known about the regulatory protein or how it is induced during the enzootic cycle of B. burgdorferi. In vitro ospC expression is always associated with the upregulation of RpoS [26,35,36,38], suggesting that the repressor is not induced in vitro. Our previous study showed that deletion of the operator does not influence in vitro ospC expression, thus, ruling out the involvement of the operator-repressor system in ospC regulation [34].…”

Section: Discussionmentioning

confidence: 99%

“…Only three σ factors can be identified from the entire genome of B. burgdorferi, including the major factor, RpoD (σ 70 ), and two alternative factors, RpoN (σ 54 ) and RpoS (σ 38 ) [25]. Moreover, the two alternative factors compose a regulatory network, in which RpoS expression depends on RpoN [26,27], greatly limiting their role in contribution to diverse gene regulation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Verification and dissection of the ospC operator by using flaB promoter as a reporter in Borrelia burgdorferi

McShan

Liang

2008

Microbial Pathogenesis

View full text Add to dashboard Cite

The Lyme disease spirochete Borrelia burgdorferi must repress expression of outer surface protein C (OspC) to effectively evade specific humoral immunity and to establish persistent infection. This ability largely relies upon a regulatory element, the only operator that has been reported in spirochetal bacteria. Immediately upstream of the ospC promoter, two sets of inverted repeats (IRs) constitute small and large palindromes, in which the right IR of the large palindrome contains the left IR of the small one, and may collectively function as the ospC operator. In the study, the large palindrome with or without the small IR was fused with a flaB promoter, which was used to drive expression of a promoterless ospC copy as a reporter gene, and introduced into OspC-deficient B. burgdorferi. The presence of the large palindrome alone significantly reduced ospC expression driven by the fused flaB promoter in the joint tissue of severe combined immunodeficiency (SCID) mice, and rescued spirochetes from elimination by passively transferred OspC antibody in infected SCID mice and specific immune responses elicited in immunocompetent mice, confirming a function of the IRs as an operator. Inclusion of the small IR further enhanced the ability of the large palindrome to reduce the activity of the fused flaB promoter, indicating that the small IR is a part of the operator. Taken together, the study led to successful verification and dissection of the ospC operator.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Verification and dissection of the ospC operator by using flaB promoter as a reporter in Borrelia burgdorferi

McShan

Liang

2008

Microbial Pathogenesis

View full text Add to dashboard Cite

show abstract

“…OspC has been shown to be required for B. burgdorferi to establish infection in mammals (8,14), as well as for spirochetal transmission from ticks to mammals (15,16). Infectivity studies demonstrate that the ospC mutant cannot establish infection in immunocompetent and SCID mice (lacking B and T cells) when inoculated at a dose of 10 3 to 10 5 spirochetes per mouse (8,(16)(17)(18)(19)(20). The ospC mutant is cleared within the first 48 h of infection in the murine host (21), suggesting a protective role of OspC against innate defenses.…”

mentioning

confidence: 99%

Outer Surface Protein OspC Is an Antiphagocytic Factor That Protects Borrelia burgdorferi from Phagocytosis by Macrophages

et al. 2015

View full text Add to dashboard Cite

cOuter surface protein C (OspC) is one of the major lipoproteins expressed on the surface of Borrelia burgdorferi during tick feeding and the early phase of mammalian infection. OspC is required for B. burgdorferi to establish infection in both immunocompetent and SCID mice and has been proposed to facilitate evasion of innate immune defenses. However, the exact biological function of OspC remains elusive. In this study, we showed that the ospC-deficient spirochete could not establish infection in NOD-scid IL2r␥ null mice that lack B cells, T cells, NK cells, and lytic complement. The ospC mutant also could not establish infection in anti-Ly6G-treated SCID and C3H/HeN mice (depletion of neutrophils). However, depletion of mononuclear phagocytes at the skin site of inoculation in SCID and C3H/HeN mice allowed the ospC mutant to establish infection in vivo. In phagocyte-depleted mice, the ospC mutant was able to colonize the joints and triggered neutrophilia during dissemination. Furthermore, we found that phagocytosis of green fluorescent protein (GFP)-expressing ospC mutant spirochetes by murine peritoneal macrophages and human THP-1 macrophage-like cells, but not in PMN-HL60, was significantly higher than parental wild-type B. burgdorferi strains, suggesting that OspC has an antiphagocytic property. In addition, overproduction of OspC in spirochetes also decreased the uptake of spirochetes by murine peritoneal macrophages. Together, our findings provide evidence that mononuclear phagocytes play a key role in clearance of the ospC mutant and that OspC promotes spirochetes' evasion of macrophages during early Lyme borreliosis. L yme disease, the most prevalent vector-borne illness in the United States (1), is a multisystem inflammatory disorder caused by infection with the spirochete Borrelia burgdorferi (2, 3). This spirochete is maintained in nature through a complex enzootic cycle involving Ixodes ticks and various small-mammal hosts. Humans, as accidental hosts, become infected after B. burgdorferiinfected ticks feed on them (4). Spirochetes replicate in the skin, spread locally, and induce an inflammatory response with a symptom known as erythema migrans, observed in most patients (2, 4). During disseminated infection, B. burgdorferi colonizes multiple tissues, leading to different clinical manifestations, including arthritis, myocarditis, and neurological and/or cutaneous abnormalities (2, 4). This acute, disseminated stage of human Lyme disease is largely recapitulated using inbred mouse strains which are susceptible to B. burgdorferi infection and develop carditis and subacute arthritis (5). Thus, the murine model provides a powerful tool to elucidate the role of spirochete virulence factors and host immunological responses during Lyme disease pathogenesis (4).The B. burgdorferi genome encodes a large number of surface lipoproteins, many of which are expressed during mammalian infection (4, 6, 7). One of these lipoproteins is the major outer surface protein C (OspC), whose production is induced within inf...

show abstract

“…burgdorferi promoter (25) linked to bosR (P flacbosR). Cells with reduced BosR have a delayed growth phenotype under all conditions but exhibit restricted cell density under microaerobic conditions.…”

mentioning

confidence: 99%

Characterization of a ConditionalbosRMutant inBorrelia burgdorferi

Hyde¹,

Shaw²,

Smith

et al. 2010

Infect Immun

View full text Add to dashboard Cite

Borrelia burgdorferi, the etiological agent of Lyme disease, adapts to unique host environments as a consequence of its complex life cycle that spans both arthropod and mammalian species. In this regard, B. burgdorferi must adapt to various environmental signals, pHs, temperatures, and O 2 and CO 2 levels to establish infectious foci. We hypothesize that the BosR protein functions as a global regulator that is required for both borrelial oxidative homeostasis and pathogenesis. To assess the role of BosR in B. burgdorferi, we constructed an IPTG (isopropyl-␤-D-thiogalactopyranoside)-regulated bosR strain. The selective decrease of bosR resulted in a change in growth when cells were cultured either anaerobically or microaerobically; however, a distinct growth defect was observed for anaerobically grown B. burgdorferi relative to the growth attenuation observed for microaerobically grown B. burgdorferi. B. burgdorferi cells in which BosR levels were reduced were more sensitive to hydrogen peroxide and produced lower levels of NapA (Dps) and SodA, proteins involved in the oxidative stress response. In addition, the levels of OspC and DbpA were also induced coincident with increased BosR levels, suggesting that BosR interfaces with the RpoS regulatory cascade, which is known to modulate virulence gene expression in B. burgdorferi. Taken together, these results indicate that BosR is involved in the resistance of B. burgdorferi to oxidative stressors and affects the expression of genes, either directly or indirectly, whose products are important in borrelial pathogenesis.

show abstract

Artificial regulation of ospC expression in Borrelia burgdorferi

Cited by 71 publications

References 69 publications

Verification and dissection of the ospC operator by using flaB promoter as a reporter in Borrelia burgdorferi

Verification and dissection of the ospC operator by using flaB promoter as a reporter in Borrelia burgdorferi

Outer Surface Protein OspC Is an Antiphagocytic Factor That Protects Borrelia burgdorferi from Phagocytosis by Macrophages

Characterization of a ConditionalbosRMutant inBorrelia burgdorferi

Contact Info

Product

Resources

About