Conformational dynamics of complement protease C1r inhibitor proteins from Lyme disease– and relapsing fever–causing spirochetes

Roy, Sourav; Booth, Charles E.; Powell-Pierce, Alexandra D.; Schulz, Anna; Skare, Jon T.; Garcia, Brandon L.

doi:10.1016/j.jbc.2023.104972

Cited by 4 publications

(18 citation statements)

References 93 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies revealed CihC of B. recurrentis and FbpC orthologs of B. miyamotoi and B. hermsii as complement-inhibiting proteins that primarily target the CP at the initial activation step by interacting with complement regulator C1-Inh and complement component C1r, respectively ( 11 , 13 ). To obtain a closer view in the complement inactivation capacity of these borrelial molecules analyzed, comparative ELISA were performed.…”

Section: Resultsmentioning

confidence: 99%

“…As FbpC of B. miyamotoi and B. hermsii of RF spirochetes and BBK32 of B. burgdorferi are known to bind to C1r ( 13 , 16 ), we wanted to close the gap of knowledge towards the interaction of C1r with CihC of B. recurrentis and the CihC/FbpC orthologs of B. parkeri and B. turicatae . By conducting ELISA, all proteins analyzed significantly bound C1r but the N-terminal CihC/FbpC fragments of B. hermsii and B. recurrentis did not ( Figure 7 ).…”

Section: Resultsmentioning

confidence: 99%

“…Previous analyses demonstrated that ectopic expression of CihC of B. recurrentis , CihC/FbpC of B. hermsii HS1 as well as BBK32 of B. burgdorferi in serum-sensitive spirochetes facilitate resistance of these gain-of-function Borrelia strains to complement-mediated killing ( 11 , 13 ). Bactericidal activity of complement could also be efficiently abrogated by pre-incubation of human serum with purified borrelial proteins displaying complement-inactivating properties that leads to the survival of categorically vulnerable spirochetes ( 13 , 16 , 18 , 23 ). To further assess the protective nature of the analyzed CihC/FbpC orthologs towards complement, a serum protection assay was conducted by employing all full-length CihC/FbpC orthologs as well as the N- and C-terminal truncated fragments.…”

Section: Resultsmentioning

confidence: 99%

“…CihC orthologs were also identified in B. turicatae , and B. parkeri all of which bound to fibronectin but not to complement regulator C1-Inh and C4BP ( 10 ). In contrast, a CihC-orthologous protein of B. hermsii strain HS1, BHA007 (later on termed FbpC) exhibits a strong affinity to human fibronectin and C1r but binds C4BP to a lesser extent ( 12 , 13 ). Furthermore, CihC and FbpC share significant sequence homology with BBK32, the first identified fibronectin-binding protein of the Lyme disease causing spirochete B. burgdorferi ( 14 , 15 ).…”

Section: Introductionmentioning

confidence: 99%

“…Phylogenetically, these proteins, including CihC of B. recurrentis and B. duttonii , are grouped into three distinct subfamilies designated FbpA, FbpB, and FbpC, respectively, whereas CihC clustered with the FbpC-like proteins of other RF spirochetes ( 12 ). Unlike B. burgdorferi , RF spirochetes including B. recurrentis , B. duttonii , B. hermsii , B. turicatae , B. parkeri , and B. miyamotoi possess up to three distinct fibronectin-binding homologs ( 10 , 11 , 13 , 18 ). Despite their sequence homology, they exhibit considerable differences in their ability to interact with fibronectin.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Multifunctional interaction of CihC/FbpC orthologs of relapsing fever spirochetes with host-derived proteins involved in adhesion, fibrinolysis, and complement evasion

Damm,

Reyer,

Langhoff

et al. 2024

Front. Immunol.

View full text Add to dashboard Cite

IntroductionRelapsing fever (RF) remains a neglected human disease that is caused by a number of diverse pathogenic Borrelia (B.) species. Characterized by high cell densities in human blood, relapsing fever spirochetes have developed plentiful strategies to avoid recognition by the host defense mechanisms. In this scenario, spirochetal lipoproteins exhibiting multifunctional binding properties in the interaction with host-derived molecules are known to play a key role in adhesion, fibrinolysis and complement activation.MethodsBinding of CihC/FbpC orthologs to different human proteins and conversion of protein-bound plasminogen to proteolytic active plasmin were examined by ELISA. To analyze the inhibitory capacity of CihC/FbpC orthologs on complement activation, a microtiter-based approach was performed. Finally, AlphaFold predictions were utilized to identified the complement-interacting residues.Results and discussionHere, we elucidate the binding properties of CihC/FbpC-orthologs from distinct RF spirochetes including B. parkeri, B. hermsii, B. turicatae, and B. recurrentis to human fibronectin, plasminogen, and complement component C1r. All CihC/FbpC-orthologs displayed similar binding properties to fibronectin, plasminogen, and C1r, respectively. Functional studies revealed a dose dependent binding of plasminogen to all borrelial proteins and conversion to active plasmin. The proteolytic activity of plasmin was almost completely abrogated by tranexamic acid, indicating that lysine residues are involved in the interaction with this serine protease. In addition, a strong inactivation capacity toward the classical pathway could be demonstrated for the wild-type CihC/FbpC-orthologs as well as for the C-terminal CihC fragment of B. recurrentis. Pre-incubation of human serum with borrelial molecules except CihC/FbpC variants lacking the C-terminal region protected serum-susceptible Borrelia cells from complement-mediated lysis. Utilizing AlphaFold2 predictions and existing crystal structures, we mapped the putative key residues involved in C1r binding on the CihC/FbpC orthologs attempting to explain the relatively small differences in C1r binding affinity despite the substitutions of key residues. Collectively, our data advance the understanding of the multiple binding properties of structural and functional highly similar molecules of relapsing fever spirochetes proposed to be involved in pathogenesis and virulence.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Multifunctional interaction of CihC/FbpC orthologs of relapsing fever spirochetes with host-derived proteins involved in adhesion, fibrinolysis, and complement evasion

Damm,

Reyer,

Langhoff

et al. 2024

Front. Immunol.

View full text Add to dashboard Cite

show abstract

Relapsing fever borreliosis

Senbill,

Zeb,

Sparagano

2025

Neglected Zoonoses and Antimicrobial Resistance

View full text Add to dashboard Cite

The dual activity of BBK32: Implications for simultaneous inhibition of borrelial-specific antibody-dependent complement activation and fibronectin binding

Powell-Pierce,

Booth,

Smith

et al. 2024

Preprint

Self Cite

View full text Add to dashboard Cite

Complement inhibition is exploited by extracellular pathogens to combat clearance.Borreliella burgdorferi, the causative agent of Lyme disease, harnesses complement evasion techniques to establish and maintain infection in mammalian hosts.B. burgdorferiencodesbbk32, a surface lipoprotein that binds extracellular matrix (ECM) components, specifically glycosoaminoglycans (GAGs) and fibronectin (Fn) within its amino terminus. In addition to its ECM-binding functions, the carboxy terminal half of BBK32 binds to the C1r protease and prevents complement activation. This classical complement inhibitory activity protectsB. burgdorferifrom complement-mediated killing following the addition of normal human serum. Herein we demonstrate that full length BBK32 binds both Fn and C1 concurrently, indicating that binding of these macromolecules do not sterically hinder their simultaneous interaction. Given the link of antibody dependence to the classical pathway, we tested how the presence of BBK32 would protectB. burgdorferifrom antibody mediated, complement dependent killing. The presence of BBK32 provided protection against borrelial-specific antibody binding and concomitant complement activationin vitro. We also demonstrated, using both fluorescence microscopy and flow cytometry, that the presence of BBK32 was required for reduced C4 deposition on the surface of borrelial cells. This work demonstrates the potential for BBK32 to simultaneously bind to both C1r and Fn and contributes to the broader understanding of the ability ofB. burgdorferito evade antibody-dependent complement-mediated killing. We contend that these observations ostensibly provideB. burgdorferiwith coincident dissemination and immune evasion activities needed for optimal survival during infection.AUTHOR SUMMARYLyme disease, caused byBorreliella burgdorferiand other related species, is the most common arthropod-borne infection in the United States. As an extracellular pathogen,B. burgdorferiis exposed to the complement system--a soluble proteolytic cascade that clears invaders. Complement is defined by three pathways known as the alternative, lectin, and classical. The classical complement cascade is activated by the binding of antibodies to a foreign or damaged cell. ForB. burgdorferi, the BBK32 surface protein is known to mute the classical pathway by binding and inhibiting the initiating protease C1r. However, no studies have addressed how BBK32 protects infectiousB. burgdorferifrom borrelial-specific antibody binding and clearance. Here we show that native BBK32 protects infectiousB. burgdorferifrom antibody-dependent, complement mediated killing. Given BBK32s other activity—namely its known adherence to fibronectin—we were interested to test if BBK32 could bind the C1 complex, which contains C1r, together with fibronectin. Our results suggest that these complex macromolecules can bind BBK32 simultaneously. These observations suggest that the dual activity of BBK32, namely fibronectin binding and C1r inhibition, are not mutually exclusive and contribute toB. burgdorferi’s ability to establish infection and evade antibody-based host clearance, respectively.

show abstract

Conformational dynamics of complement protease C1r inhibitor proteins from Lyme disease– and relapsing fever–causing spirochetes

Cited by 4 publications

References 93 publications

Multifunctional interaction of CihC/FbpC orthologs of relapsing fever spirochetes with host-derived proteins involved in adhesion, fibrinolysis, and complement evasion

Multifunctional interaction of CihC/FbpC orthologs of relapsing fever spirochetes with host-derived proteins involved in adhesion, fibrinolysis, and complement evasion

Relapsing fever borreliosis

The dual activity of BBK32: Implications for simultaneous inhibition of borrelial-specific antibody-dependent complement activation and fibronectin binding

Contact Info

Product

Resources

About