In vitro generation and bioactivity evaluation of C-reactive protein intermediate

Lv, Jian-Min; Wang, Mingyu

doi:10.1371/journal.pone.0198375

Cited by 13 publications

(15 citation statements)

References 38 publications

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“…It has been shown that the pentameric conformation of CRP is altered in a variety of experimental conditions mimicking an inflammatory milieu and, in its alternate pentameric conformation, CRP binds to immobilized complement inhibitor factor H also (37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47). We hypothesize that in order to protect mice against late-stage infection, a structural change in CRP is needed, followed by the interaction between structurally altered CRP and recruited factor H on the pneumococcal surface, and that was not happening in mice.…”

Section: Introductionmentioning

confidence: 93%

Treatment of Pneumococcal Infection by Using Engineered Human C-Reactive Protein in a Mouse Model

et al. 2020

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C-reactive protein (CRP) binds to several species of bacterial pathogens including Streptococcus pneumoniae. Experiments in mice have revealed that one of the functions of CRP is to protect against pneumococcal infection by binding to pneumococci and activating the complement system. For protection, however, CRP must be injected into mice within a few hours of administering pneumococci, that is, CRP is protective against early-stage infection but not against late-stage infection. It is assumed that CRP cannot protect if pneumococci got time to recruit complement inhibitor factor H on their surface to become complement attack-resistant. Since the conformation of CRP is altered under inflammatory conditions and altered CRP binds to immobilized factor H also, we hypothesized that in order to protect against latestage infection, CRP needed to change its structure and that was not happening in mice. Accordingly, we engineered CRP molecules (E-CRP) which bind to factor H on pneumococci but do not bind to factor H on any host cell in the blood. We found that E-CRP, in cooperation with wild-type CRP, was protective regardless of the timing of administering E-CRP into mice. We conclude that CRP acts via two different conformations to execute its anti-pneumococcal function and a model for the mechanism of action of CRP is proposed. These results suggest that pre-modified CRP, such as E-CRP, is therapeutically beneficial to decrease bacteremia in pneumococcal infection. Our findings may also have implications for infections with antibiotic-resistant pneumococcal strains and for infections with other bacterial species that use host proteins to evade complement-mediated killing.

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Section: Introductionmentioning

confidence: 93%

Treatment of Pneumococcal Infection by Using Engineered Human C-Reactive Protein in a Mouse Model

et al. 2020

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“…enriched at inflammatory loci (3,4,(8)(9)(10)(11). One of the activated conformations has been suggested to maintain the pentameric assembly while showing a neo-epitope (a.a. 199-206) that is otherwise shielded by the native inter-subunit contacts (12)(13)(14)(15). Such a conformation would imply that there is some degree of plasticity in the seemingly rigid assembly of pentameric CRP.…”

Section: Pentameric Assembly Of Crp Exhibits Pronounced Plasticitymentioning

confidence: 99%

Celluar Folding Determinants and Conformational Plasticity of Native C-Reactive Protein

Chen

Liu

et al. 2020

Front. Immunol.

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C-reactive protein (CRP) is an acute phase reactant secreted by hepatocytes as a pentamer. The structure formation of pentameric CRP has been demonstrated to proceed in a stepwise manner in live cells. Here, we further dissect the sequence determinants that underlie the key steps in cellular folding and assembly of CRP. The initial folding of CRP subunits depends on a leading sequence with a conserved dipeptide that licenses the formation of the hydrophobic core. This drives the bonding of the intra-subunit disulfide requiring a favorable niche largely conferred by a single residue within the C-terminal helix. A conserved salt bridge then mediates the assembly of folded subunits into pentamer. The pentameric assembly harbors a pronounced plasticity in inter-subunit interactions, which may form the basis for a reversible activation of CRP in inflammation. These results provide insights into how sequence constraints are evolved to dictate structure and function of CRP.

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“…All three forms, native pentameric, non-native pentameric, and mCRP display different ligand recognition functions in vitro (2, 102–104). Under conditions of low pH, reduced calcium levels and oxidation-reduction, CRP is converted to a non-native conformation but remains pentameric (48–50, 105–107). When non-native CRP binds to a non-PCh ligand, it denatures further to mCRP.…”

Section: Crp As An Anti-inflammatory Moleculementioning

confidence: 99%

“…Surface-immobilization of CRP generates a preservable intermediate with dual antigenicity expression of both CRP and mCRP. The intermediate exhibits modified bioactivities, such as a high affinity with solution-phase proteins (107). It has been shown that mCRP but not CRP is the major isoform present in local inflammatory lesions (111).…”

Section: Crp As An Anti-inflammatory Moleculementioning

confidence: 99%

Structure-Function Relationships of C-Reactive Protein in Bacterial Infection

Ngwa

Agrawal

2019

Front. Immunol.

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One host defense function of C-reactive protein (CRP) is to protect against Streptococcus pneumoniae infection as shown by experiments employing murine models of pneumococcal infection. The protective effect of CRP is due to reduction in bacteremia. There is a distinct relationship between the structure of CRP and its anti-pneumococcal function. CRP is functional in both native and non-native pentameric structural conformations. In the native conformation, CRP binds to pneumococci through the phosphocholine molecules present on the C-polysaccharide of the pneumococcus and the anti-pneumococcal function probably involves the known ability of ligand-complexed CRP to activate the complement system. In the native structure-function relationship, CRP is protective only when given to mice within a few hours of the administration of pneumococci. The non-native pentameric conformation of CRP is created when CRP is exposed to conditions mimicking inflammatory microenvironments, such as acidic pH and redox conditions. In the non-native conformation, CRP binds to immobilized complement inhibitor factor H in addition to being able to bind to phosphocholine. Recent data using CRP mutants suggest that the factor H-binding function of non-native CRP is beneficial: in the non-native structure-function relationship, CRP can be given to mice any time after the administration of pneumococci irrespective of whether the pneumococci became complement-resistant or not. In conclusion, while native CRP is protective only against early stage infection, non-native CRP is protective against both early stage and late stage infections. Because non-native CRP displays phosphocholine-independent anti-pneumococcal activity, it is quite possible that CRP functions as a general anti-bacterial molecule.

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In vitro generation and bioactivity evaluation of C-reactive protein intermediate

Cited by 13 publications

References 38 publications

Treatment of Pneumococcal Infection by Using Engineered Human C-Reactive Protein in a Mouse Model

Treatment of Pneumococcal Infection by Using Engineered Human C-Reactive Protein in a Mouse Model

Celluar Folding Determinants and Conformational Plasticity of Native C-Reactive Protein

Structure-Function Relationships of C-Reactive Protein in Bacterial Infection

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