Enzymatic Modification of Lipid A by ArnT Protects Bordetella bronchiseptica against Cationic Peptides and Is Required for Transmission

Rolin, Olivier; Muse, Sarah J.; Safi, Chetan Y.; Elahi, Shokrollah; Gerdts, Volker; Hittle, Lauren E.; Ernst, Robert K.; Harvill, Eric T.; Preston, Andrew

doi:10.1128/iai.01260-12

Cited by 23 publications

(24 citation statements)

References 31 publications

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“…The naturally occurring B. pertussis strains described here could also be less virulent due to similar mechanisms. These strains do not activate TLR4 signaling and, in addition, the lack of GlcN modification of the LOS molecules leads to decreased resistance to antimicrobial peptides, as shown in recent studies using GLcN Ϫ mutants of B. pertussis and the closely related B. bronchiseptica (67,68). This however remains to be investigated in larger clinical cohorts.…”

Section: Discussionmentioning

confidence: 89%

Bordetella pertussis Naturally Occurring Isolates with Altered Lipooligosaccharide Structure Fail To Fully Mature Human Dendritic Cells

et al. 2015

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bBordetella pertussis is a Gram-negative bacterium and the causative agent of whooping cough. Despite high vaccination coverage, outbreaks are being increasingly reported worldwide. Possible explanations include adaptation of this pathogen, which may interfere with recognition by the innate immune system. Here, we describe innate immune recognition and responses to different B. pertussis clinical isolates. By using HEK-Blue cells transfected with different pattern recognition receptors, we found that 3 out of 19 clinical isolates failed to activate Toll-like receptor 4 (TLR4). These findings were confirmed by using the monocytic MM6 cell line. Although incubation with high concentrations of these 3 strains resulted in significant activation of the MM6 cells, it was found to occur mainly through interaction with TLR2 and not through TLR4. When using live bacteria, these 3 strains also failed to activate TLR4 on HEK-Blue cells, and activation of MM6 cells or human monocyte-derived dendritic cells was significantly lower than activation induced by the other 16 strains. Mass spectrum analysis of the lipid A moieties from these 3 strains indicated an altered structure of this molecule. Gene sequence analysis revealed mutations in genes involved in lipid A synthesis. Findings from this study indicate that B. pertussis isolates that do not activate TLR4 occur naturally and that this phenotype may give this bacterium an advantage in tempering the innate immune response and establishing infection. Knowledge on the strategies used by this pathogen in evading the host immune response is essential for the improvement of current vaccines or for the development of new ones.T he innate immune system is the first line of defense against invading pathogens. In order to recognize these microorganisms, innate immune cells express multiple pathogen recognition receptors (PRR) consisting of various receptor families, including the most-studied Toll-like receptors (TLRs) (1). Evasion of this first recognition can be critical for the pathogen establishing infection. Additionally, the innate immune system is essential for the induction and regulation of the adaptive response. For example, dendritic cells (DCs) can produce interleukin-12p70 (IL12p70), which is associated with the differentiation of T helper 1 (Th1) cells or cytotoxic T cells (2, 3) and IL-1␤, IL-6, and IL-23, which are required for differentiation and survival of Th17 cells (4, 5). Pathogen adaptation, through changes in the structure or expression of molecules which interact with the host, might allow the pathogen to escape the host immune responses.Pertussis, also referred to as whooping cough, is a humanspecific respiratory disease caused by the Gram-negative bacterium Bordetella pertussis. It has been shown that B. pertussis is able to activate both TLR2 and TLR4 signaling on innate immune cells, which is essential for inducing protective immunity against this bacterium (6-9). A well-defined ligand for TLR4 is lipopolysaccharide (LPS), which is produced by Gram-nega...

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Section: Discussionmentioning

confidence: 89%

Bordetella pertussis Naturally Occurring Isolates with Altered Lipooligosaccharide Structure Fail To Fully Mature Human Dendritic Cells

et al. 2015

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“…Despite this variation, GlcN modification still confers resistance to polymyxin B in both these species. When comparing the effect on TLR4 activation in the natural hosts-humans versus small mammals, the LgmB Br -mediated modification in B. bronchiseptica does not affect activation of mouse TLR4, whereas the GlcN modification in B. pertussis increases activation of human TLR4 (4,11). This adds a layer of complexity in the B. pertussis and human system that is not present in B. bronchiseptica and mice.…”

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confidence: 99%

“…Recently, the GlcN modification in B. bronchiseptica was linked to successful transmission between mice and colonization at lower infectious doses (11). It remains to be seen whether this also holds true for B. pertussis infections in humans.…”

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confidence: 99%

“…In this context, the recent findings that the arnT (Bordetella bronchiseptica lgmB [lgmB Br ]) gene in Bordetella bronchiseptica controls resistance to polymyxin B and pBD1 (11), may not have applied a priori to B. pertussis, especially considering the differences in LPS between these two species. B. pertussis has penta-acyl LPS with no O antigen, whereas B. bronchiseptica LPS is hexa-acylated and has a long O antigen, which has been shown to confer resistance to CAMPs (6,11,12). Despite this variation, GlcN modification still confers resistance to polymyxin B in both these species.…”

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confidence: 99%

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Bordetella pertussis Lipid A Glucosamine Modification Confers Resistance to Cationic Antimicrobial Peptides and Increases Resistance to Outer Membrane Perturbation

Shah

Hancock

Fernandez

2014

Antimicrob Agents Chemother

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Bordetella pertussis, the causative agent of whooping cough, has many strategies for evading the human immune system. Lipopolysaccharide (LPS) is an important Gram-negative bacterial surface structure that activates the immune system via Toll-like receptor 4 and enables susceptibility to cationic antimicrobial peptides (CAMPs). We show modification of the lipid A region of LPS with glucosamine increased resistance to numerous CAMPs, including LL-37. Furthermore, we demonstrate that this glucosamine modification increased resistance to outer membrane perturbation.

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“…The modification of lipid A of B. cenocepacia with L-Ara4N is constitutive and essential for B. cenocepacia cell viability (Ortega et al 2007), as L-Ara4N-modified lipid A is required for LPS export to the outer membrane (Hamad et al 2012;Ortega et al 2007). Further, L-Ara4N ligation to lipid A confers PmB resistance to B. cenocepacia and other bacteria such as Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa, Bor.detella bronchiseptica, Yersinia enterocolitica, Yersinia pestis and Proteus mirabilis (Kaca et al 1990;Boll et al 1994;Guo et al 1997Guo et al , 1998Ernst et al 1999;Loutet and Valvano 2011;Rolin et al 2014). …”

Section: Introductionmentioning

confidence: 99%

ArnT proteins that catalyze the glycosylation of lipopolysaccharide share common features with bacterialN-oligosaccharyltransferases

Tavares-Carreón¹,

Mohamed²,

Andrade³

et al. 2015

Glycobiology

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ArnT is a glycosyltransferase that catalyzes the addition of 4-amino-4-deoxy-L-arabinose (L-Ara4N) to the lipid A moiety of the lipopolysaccharide. This is a critical modification enabling bacteria to resist killing by antimicrobial peptides. ArnT is an integral inner membrane protein consisting of 13 predicted transmembrane helices and a large periplasmic C-terminal domain. We report here the identification of a functional motif with a canonical consensus sequence DEXRYAX (5) MX (3) GXWX (9) YFEKPX (4) W spanning the first periplasmic loop, which is highly conserved in all ArnT proteins examined. Site-directed mutagenesis demonstrated the contribution of this motif in ArnT function, suggesting that these proteins have a common mechanism. We also demonstrate that the Burkholderia cenocepacia and Salmonella enterica serovar Typhimurium ArnT C-terminal domain is required for polymyxin B resistance in vivo. Deletion of the C-terminal domain in B. cenocepacia ArnT resulted in a protein with significantly reduced in vitro binding to a lipid A fluorescent substrate and unable to catalyze lipid A modification with L-Ara4N. An in silico predicted structural model of ArnT strongly resembled the tertiary structure of Campylobacter lari PglB, a bacterial oligosaccharyltransferase involved in protein N-glycosylation. Therefore, distantly related oligosaccharyltransferases from ArnT and PglB families operating on lipid and polypeptide substrates, respectively, share unexpected structural similarity that could not be predicted from direct amino acid sequence comparisons. We propose that lipid A and protein glycosylation enzymes share a conserved catalytic mechanism despite their evolutionary divergence.

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Enzymatic Modification of Lipid A by ArnT Protects Bordetella bronchiseptica against Cationic Peptides and Is Required for Transmission

Cited by 23 publications

References 31 publications

Bordetella pertussis Naturally Occurring Isolates with Altered Lipooligosaccharide Structure Fail To Fully Mature Human Dendritic Cells

Bordetella pertussis Naturally Occurring Isolates with Altered Lipooligosaccharide Structure Fail To Fully Mature Human Dendritic Cells

Bordetella pertussis Lipid A Glucosamine Modification Confers Resistance to Cationic Antimicrobial Peptides and Increases Resistance to Outer Membrane Perturbation

ArnT proteins that catalyze the glycosylation of lipopolysaccharide share common features with bacterialN-oligosaccharyltransferases

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