Common antigen lipopolysaccharide from Pseudomonas aeruginosa AK1401 as a receptor for bacteriophage A7

Abstract

A-band, a D-rhamnose-containing common lipopolysaccharide antigen isolated from Pseudomonas aeruginosa AK1401, was found to be a receptor for bacteriophage A7. The phage-borne rhamnanase was capable of hydrolyzing the A-band to expose core-lipid A containing only two or three rhamnose repeats. Interaction of the hydrolyzed A-band with core-or lipid A-specific monoclonal antibodies revealed that common epitopes exist in the inner core and lipid A regions, while the outer core of A-band appears to be different from that of the serotype-specific (B-band) lipopolysaccharide.Lipopolysaccharide (LPS), a major component of the gram-negative outer membrane (17), is composed of heteropolysaccharide covalently linked to lipid A (9, 21). The heteropolysaccharide consists of three regions: a diglucosamine backbone, the oligosaccharide core, and the 0-antigenic polysaccharide chain. Specific structures within the LPS molecule serve as receptors for a variety of bacteriophages (15,29). Phage adsorption to its receptor is highly specific (15). Phage resistance that results from changes in LPS structure usually indicates that the LPS is the surface receptor (29), and the structural change identifies the region of the LPS comprising the receptor. Since the structure of the 0-serotype-specific antigen varies from strain to strain, the host range of a phage whose receptor is the 0 polysaccharide is rather narrow (9,15). One characteristic of 0-specific phage is that during infection they often hydrolyze the 0 antigen, destroying the initial receptor (29). In many strains of Pseudomonas aeruginosa, a second LPS species whose polysaccharide chain differs serologically and structurally from the 0-antigen chain is present (10, 14, 16, 22-24, 30, 31). This LPS has been termed A-band or common antigen LPS. The common antigen polysaccharide of P. aeruginosa is a regular homopolymer of rhamnose. On the basis of nuclear magnetic resonance and chemical analyses, the structure has been shown to consist of the repeating unit (2,10,30,31). Interestingly, the structure proposed for the repeating unit of the rhamnan chain in the common antigen LPS of P. aeruginosa is identical to that reported for the O-polysaccharide chain in the LPS of Pseudomonas syringae pv. morsprunorum C28 (26).The 0 polysaccharide of P. syringae pv. morsprunorum C28 LPS, which is composed entirely of rhamnose (26), is specifically cleaved and released as oligosaccharides by the action of a rhamnanase borne on the typing phage A7 (25). This phage uses the LPS as its initial binding site (20,25). Thus, it is expected that the common antigen (A-band) LPS from P. aeruginosa will also serve as a substrate for phage A7. This phage will serve as a tool to remove the polyrhamnose chain from the A-band LPS for detailed analysis of the core and lipid A of this molecule. In this report, we present evidence to show that phage A7 binds to and hydrolyzes the * Corresponding author. polyrhamnose chain of the A-band LPS from P. aeruginosa AK1401 and that the phage-digested A-band LPS ca...

Single-Nucleotide Polymorphisms Found in the migA and wbpX Glycosyltransferase Genes Account for the Intrinsic Lipopolysaccharide Defects Exhibited by Pseudomonas aeruginosa PA14

“…CPA was found to be a receptor for bacteriophage A7 (27) and for lectin-like bacteriocins (28). Lectin-like bacteriocins, such as pyocin L1 and putidacin L1, display a genus-specific killing activity.…”

“…The importance of the latter operon to CPA biosynthesis has been established based on evidence collected from mutagenesis and overexpression experiments (25). CPA was found to play important biological roles as a receptor for bacteriophage A7 (27) and lectin-like bacteriocins (28) and as a surface antigen for P. aeruginosa that is important for adherence to human bronchial epithelial cells (29). In a recent study, Murphy et al (30) showed that CPA is required for strain PAO1 to develop mature and robust biofilms.…”

Monoclonal antibodies that distinguish inner core, outer core, and lipid A regions of Pseudomonas aeruginosa lipopolysaccharide

“…Acid hydrolysis cleaves the ketosidic linkage between the Kdo residue and the lipid A molecule. This treatment was used effectively in a previous study (46), and it essentially dissociates the core oligosaccharide and O-polysaccharide moieties, leaving only the unsubstituted lipid A molecule. In nonhydrolyzed immunoblots, MAb 177 reacted with only a single fast-migrating LPS band (Fig.…”

Pseudomonas aeruginosa B-band O-antigen chain length is modulated by Wzz (Ro1)

“…Bastin et al (2) suggested that Wzz acts as a molecular timer, allowing polymerization by Wzy to continue either for a set amount of time or until a particular length of O antigen has formed, at which point the polymer is transferred onto lipid A core. An alternate hypothesis, proposed by Morona and colleagues (37), is that Wzz acts as a molecular chaperone, influencing the stoichiometry of Wzy and the O-antigen ligase, WaaL (RfaL [34]), such that the balance between polymerization and ligation events is altered.Pseudomonas aeruginosa is a gram-negative, opportunistic pathogen which produces a number of virulence factors, including exopolysaccharides such as alginate and two distinct forms of LPS (9,36,40). A-band LPS, the common antigen, is expressed by most serotypes and contains a homopolymer of ␣-D-rhamnose (30).…”

“…Pseudomonas aeruginosa is a gram-negative, opportunistic pathogen which produces a number of virulence factors, including exopolysaccharides such as alginate and two distinct forms of LPS (9,36,40). A-band LPS, the common antigen, is expressed by most serotypes and contains a homopolymer of ␣-D-rhamnose (30).…”