Bacillus anthracis Spore Surface Protein BclA Mediates Complement Factor H Binding to Spores and Promotes Spore Persistence

Wang, Yanyu; Jenkins, Sarah A.; Gu, Cheng; Ankita, Shree; Martinez-Moczygemba, Margarita; Herold, Jennifer; Botto, Marina; Wetsel, Rick A.; Xu, Yi

doi:10.1371/journal.ppat.1005678

Cited by 30 publications

(27 citation statements)

References 89 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…C1q is a component of human complement pathway which binds IgG, and apoptotic keratinocytes [78, 79]. BclA is implicated in a number of processes in B. anthracis infection including specific targeting to macrophages [80], and immunosuppressive activity via binding to complement factor H [81]. Notably, BclA does not appear to be directly involved in attachment as ΔbclA spores show no reduced binding to host cells but do exhibit a reduction in specific targeting to professional phagocytic cells [80].…”

Section: Discussionmentioning

confidence: 99%

De novoassembly of thePasteuria penetransgenome reveals high plasticity, host dependency, and BclA-like collagens

Orr¹,

Mauchline²,

Cock³

et al. 2018

Preprint

View full text Add to dashboard Cite

12Pasteuria penetrans is a gram-positive endospore forming bacterial parasite of Meloidogyne spp. the 13 most economically damaging genus of plant parasitic nematodes globally. The obligate antagonistic 14 nature of P. penetrans makes it an attractive candidate biological control agent. However, deployment 15 of P. penetrans for this purpose is inhibited by a lack of understanding of its metabolism and the 16 molecular mechanics underpinning parasitism of the host, in particular the initial attachment of the 17 endospore to the nematode cuticle. Several attempts to assemble the genomes of species within this 18 genus have been unsuccessful. Primarily this is due to the obligate parasitic nature of the bacterium 19which makes obtaining genomic DNA of sufficient quantity and quality which is free from 20 contamination challenging. Taking advantage of recent developments in whole genome amplification, 21 long read sequencing platforms, and assembly algorithms, we have developed a protocol to generate 22 large quantities of high molecular weight genomic DNA from a small number of purified endospores. 23We demonstrate this method via genomic assembly of P. penetrans. This assembly reveals a reduced 24 genome of 2.64Mbp estimated to represent 86% of the complete sequence; its reduced metabolism 25 reflects widespread reliance on the host and possibly associated organisms. Additionally, apparent 26 expansion of transposases and prediction of partial competence pathways suggest a high degree of 27 genomic plasticity. Phylogenetic analysis places our sequence within the Bacilli, and most closely 28 related to Thermoactinomyces species. Seventeen predicted BclA-like proteins are identified which 29 may be involved in the determination of attachment specificity. This resource may be used to develop 30 in vitro culture methods and to investigate the genetic and molecular basis of attachment specificity. 31 32 33

show abstract

Section: Discussionmentioning

confidence: 99%

De novoassembly of thePasteuria penetransgenome reveals high plasticity, host dependency, and BclA-like collagens

Orr¹,

Mauchline²,

Cock³

et al. 2018

Preprint

View full text Add to dashboard Cite

show abstract

“…This BclA glycoprotein may have a role in spore protection (Boydston et al, 2005) and may play a role in host phagocytosis of the spore (Gu et al, 2012). It has recently been shown to mediate an immune inhibition mechanism that promotes spore persistence in mouse lung (Wang et al, 2016). ExsFA (also named BxpB) is a 17 kDa exosporium protein required for the efficient attachment of BclA to form the nap on the exosporium Sylvestre et al, 2005;Thompson et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Molecular tiling on the surface of a bacterial spore – the exosporium of the Bacillus anthracis/cereus/thuringiensis group

Terry

Jiang

Radford

et al. 2017

Molecular Microbiology

View full text Add to dashboard Cite

SummaryBacteria of the genera Bacillus and Clostridium form highly resistant spores, which in the case of some pathogens act as the infectious agents. An exosporium forms the outermost layer of some spores; it plays roles in protection, adhesion, dissemination, host targeting in pathogens and germination control. The exosporium of the Bacillus cereus group, including the anthrax pathogen, contains a 2D‐crystalline basal layer, overlaid by a hairy nap. BclA and related proteins form the hairy nap, and require ExsFA (BxpB) for their localization on the basal layer. Until now, the identity of the main structural protein components of the basal layer was unknown. We demonstrate here that ExsY forms one of the essential components. Through heterologous expression in Escherichia coli, we also demonstrate that ExsY can self‐assemble into ordered 2D arrays that mimic the structure of the exosporium basal layer. Self‐assembly is likely to play an important role in the construction of the exosporium. The ExsY array is stable to heat and chemical denaturants, forming a robust layer that would contribute to overall spore resistance. Our structural analysis also provides novel insight into the location of other molecular components anchored onto the exosporium, such as BclA and ExsFA.

show abstract

“…A32723). Dose-dependent C3b binding was analyzed by incubating bacteria with a concentration gradient (10,25,50, and 100%) of NHS (Merck). CRP and SAP binding on the bacterial surface was assessed using mouse anti-human CRP (Thermo Fisher, Cat.…”

Section: Flow Cytometry-based Binding Assaymentioning

confidence: 99%

“…These include the expression of cellular components and proteins on the pathogen surface that inhibit complement activation (18), blocking, or destabilization of the C3 convertase (19,20); recruitment of host complement regulatory proteins on the pathogen surface (21,22); and complement degradation by host plasminogen (23,24). Previous reports have suggested that the B. anthracis spore coat protein BclA has the propensity to bind with complement factor H (FH) and human serum plasminogen (24,25), which leads to C3 breakdown and imparts anti-opsonic properties to the spore. Considering the common characteristics of complement evasion and a higher survival rate exhibited by encapsulated bacteria compared with their non-encapsulated counterparts, it is conceivable that the B. anthracis PGA capsule may also exhibit complement antagonistic properties (11).…”

Section: Introductionmentioning

confidence: 99%

Bacillus anthracis Poly-γ-D-Glutamate Capsule Inhibits Opsonic Phagocytosis by Impeding Complement Activation

2020

View full text Add to dashboard Cite

Bacillus anthracis poly-γ-D-glutamic acid (PGA) capsule is an essential virulent factor that helps the bacterial pathogen to escape host immunity. Like other encapsulated bacterial species, the B. anthracis capsule may also inhibit complement-mediated clearance and ensure bacterial survival in the host. Previous reports suggest that B. anthracis spore proteins inhibit complement activation. However, the mechanism through which the B. anthracis capsule imparts a survival advantage to the active bacteria has not been demonstrated till date. Thus, to evaluate the role of the PGA capsule in evading host immunity, we have undertaken the present head-to-head comparative study of the phagocytosis and complement activation of non-encapsulated and encapsulated B. anthracis strains. The encapsulated virulent strain exhibited resistance toward complement-dependent and complement-independent bacterial phagocytosis by human macrophages. The non-encapsulated Sterne strain was highly susceptible to phagocytosis by THP-1 macrophages, after incubation with normal human serum (NHS), heat-inactivated serum, and serum-free media, thus indicating that the capsule inhibited both complement-dependent and complement-independent opsonic phagocytosis. An increased binding of C3b and its subsequent activation to C3c and C3dg, which functionally act as potent opsonins, were observed with the non-encapsulated Sterne strain compared with the encapsulated strain. Other known mediators of complement fixation, IgG, C-reactive protein (CRP), and serum amyloid P component (SAP), also bound more prominently with the non-encapsulated Sterne strain. Studies with complement pathway-specific, component-deficient serum demonstrated that the classical pathway was primarily involved in mediating C3b binding on the non-encapsulated bacteria. Both strains equally bound the complement regulatory proteins C4BP and factor H. Importantly, we demonstrated that the negative charge of the PGA capsule was responsible for the differential binding of the complement proteins between the non-encapsulated and encapsulated strains. At lower pH closer to the isoelectric point of PGA, the neutralization of the negative charge was associated with Sharma et al. Bacillus anthracis Poly-γ-D-Glutamate Capsule an increased binding of C3b and IgG with the encapsulated B. anthracis strain. Overall, our data have demonstrated that the B. anthracis capsule inhibits complement fixation and opsonization resulting in reduced phagocytosis by macrophages, thus allowing the bacterial pathogen to evade host immunity.

show abstract

Bacillus anthracis Spore Surface Protein BclA Mediates Complement Factor H Binding to Spores and Promotes Spore Persistence

Cited by 30 publications

References 89 publications

De novoassembly of thePasteuria penetransgenome reveals high plasticity, host dependency, and BclA-like collagens

De novoassembly of thePasteuria penetransgenome reveals high plasticity, host dependency, and BclA-like collagens

Molecular tiling on the surface of a bacterial spore – the exosporium of the Bacillus anthracis/cereus/thuringiensis group

Bacillus anthracis Poly-γ-D-Glutamate Capsule Inhibits Opsonic Phagocytosis by Impeding Complement Activation

Contact Info

Product

Resources

About