Bordetella parapertussis PagP Mediates the Addition of Two Palmitates to the Lipopolysaccharide Lipid A

Abstract

T he genus Bordetella contains nine species, three of which have been studied in detail: B. pertussis, B. parapertussis, and B. bronchiseptica. B. pertussis and B. parapertussis are the causative agents of whooping cough. While long considered a disease of infants and children, it is now recognized that infections occur in adults, although they are milder than the classic whooping cough described in children (1-5). B. pertussis is considered the major pathogen of whooping cough; however, the prevalence of B. parapertussis in disease is not well understood but may be a significant contributor to the overall burden (6). Symptoms of B. parapertussis and B. pertussis disease are clinically indistinguishable and include a prolonged cough, whooping, paroxysms, vomiting, and cyanosis (7), leading to increased mortality in infected children; however, B. parapertussis is often considered to cause milder disease than B. pertussis (7). In many countries, whooping cough is controlled by vaccination against B. pertussis. However, many countries have recently suffered major outbreaks despite continuous high levels of vaccine coverage, initiating renewed interest in whooping cough vaccinology. The acellular pertussis vaccines (DTaP and Tdap) used in most developed countries do not result in protection against B. parapertussis, likely due to the B. parapertussis lipopolysaccharide (LPS) O antigen inhibiting the binding of antibodies to the bacterium (8).LPS is the major component of the outer leaflet of the outer membrane of Gram-negative bacteria. The lipid A region imparts the endotoxin activity of LPS (9) that arises when lipid A binds to a host membrane complex that includes and activates signaling by Toll-like receptor 4 (TLR4) (10), resulting in the expression of many proinflammatory cytokines and chemokines in cells of the innate immune system. TLR4 signaling is also important for the activation of adaptive immunity, particularly through the activation of dendritic cells (DCs), which act as antigen-presenting cells (APCs) for T cells. Thus, lipid A-TLR4 interactions are central to the host immune response to Gram-negative bacteria, including Bordetella species.Bordetella subspecies exhibit extensive heterogeneity in their lipid A structure, arising from both species-specific differences in and species-variable expression of specific lipid A-modifying enzymes (11,12). Previously, we demonstrated that B. bronchiseptica pagP (pagP BB ) encodes a lipid A palmitoyl transferase that is responsible for the presence of palmitate in lipid A. The expression of pagP BB is regulated by the Bvg two-component system (13) that regulates the expression of many Bordetella genes that are involved in pathogenesis (14). pagP BB is maximally expressed in the Bvgplus (Bvg ϩ ) phase that is adopted when the system is active and includes the expression of many of the toxins and adhesins considered important for infection. When the Bvg system is inactive, the bacteria adopt the Bvg-minus (Bvg Ϫ ) phase, and the expression of these virulence gene...

Outer-Membrane-Vesicle–Associated O Antigen, a Crucial Component for Protecting Against Bordetella parapertussis Infection

“…To characterize the LPS in both OMVs, one-dimensional electrophoresis was performed (Figure 1B ). By this technique, we detected that the LPS present in the OMVs preparation derived from B. parapertussis AR729 had the characteristic electrophoretic profile of the LPS belonged from human strains of B. parapertussis ( 16 , 32 ) consisting in a faster-migrating LPS—B band that corresponds to the Lipid A- core structure together with a ladder arrangement of high molecular mass bands that correspond to the O antigen (O-Ag, a polymer of 2,3-diacetamido-2,3-dideoxy-α-galacturonic acid ( 33 )). The presence of the O-Ag band in the LPS from AR729 was confirmed by an immunoblot assay using a polyclonal serum that only recognized the O antigen (Figure 1C) .…”

Bordetella holmesii: Lipid A Structures and Corresponding Genomic Sequences Comparison in Three Clinical Isolates and the Reference Strain ATCC 51541

“… The presence of a secondary palmitoyl chain at two positions of lipid A (3′ and 2). We previously described the presence of such palmitoyl chains at C-3′ in B. avium , and in both C3′ and C2 in B. parapertussis [ 27 , 45 ] as a result of PagP action. In the present study, we observed no pagP sequence difference between the three tested isolates.…”

Remodelling of the Gram-negative bacterial Kdo2-lipid A and its functional implications

“… B. bronchiseptica PagP adds C16 : 0 at the 3′-position whereas Bordetella parapertussis PagP transfers palmitates to the lipid A C-2 and C-3′ positions [136]. The B.…”

“…In Bordetella species, PagP is regulated by Bvg two-component system and the PagP proteins in members of this genus can have strict or dual specificity for the attachment site in the lipid A. B. bronchiseptica PagP adds C16 : 0 at the 3′-position whereas Bordetella parapertussis PagP transfers palmitates to the lipid A C-2 and C-3′ positions [136]. The B. bronchiseptica PagP modification is required for resistance to antibody-dependent complement-mediated killing in a murine model of infection.…”