Mapping the surface regions of <i>Pseudomonas aeruginosa</i> PAK pilin: the importance of the <i>C</i>‐terminal region for adherence to human buccal epithelial cells

Lee, K. K.; Doig, P.; Irvin, Randall T.; Paranchych, W.; Hodges, Robert S.

doi:10.1111/j.1365-2958.1989.tb00135.x

Cited by 59 publications

(43 citation statements)

References 32 publications

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“…The value of the 1244 glycan at the pilin C terminus may be related to its proximity to the DSL, a structure that facilitates adhesion to host tissue by attachment to surface glycolipids (31). This structure, although exposed at the pilus tip, is at least partially buried between the subunits of the fiber shaft (32). We have previously shown that the glycan is located on the fiber surface where it attenuates the natural hydrophobicity of the pilus (47).…”

Section: Discussionmentioning

confidence: 99%

Glycosylation Substrate Specificity of Pseudomonas aeruginosa 1244 Pilin

Horzempa

Comer

Davis

et al. 2006

Journal of Biological Chemistry

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The ␤-carbon of the Pseudomonas aeruginosa 1244 pilin C-terminal Ser is a site of glycosylation. The present study was conducted to determine the pilin structures necessary for glycosylation. It was found that although Thr could be tolerated at the pilin C terminus, the blocking of the Ser carboxyl group with the addition of an Ala prevented glycosylation. Pilin from strain PA103 was not glycosylated by P. aeruginosa 1244, even when the C-terminal residue was converted to Ser. Substituting the disulfide loop region of strain PA103 pilin with that of strain 1244 allowed glycosylation to take place. Neither conversion of 1244 pilin disulfide loop Cys residues to Ala nor the deletion of segments of this structure prevented glycosylation. It was noted that the PA103 pilin disulfide loop environment was electronegative, whereas that of strain 1244 pilin had an overall positive charge. Insertion of a positive charge into the PA103 pilin disulfide loop of a mutant containing Ser at the C terminus allowed glycosylation to take place. Extending the "tail" region of the PA103 mutant pilin containing Ser at its terminus resulted in robust glycosylation. These results suggest that the terminal Ser is the major pilin glycosylation recognition feature and that this residue cannot be substituted at its carboxyl group. Although no other specific recognition features are present, the pilin surface must be compatible with the reaction apparatus for glycosylation to occur.Pseudomonas aeruginosa is a Gram-negative bacterium that expresses polar filaments called type IV pili. These pili are polymers of a primarily proteinaceous subunit referred to as pilin. Although all known type IV pilins are modified by the cleavage of a leader sequence followed by the N-methylation of the exposed Phe (1), the pilin of P. aeruginosa 1244 is additionally glycosylated. This glycosylation requires the presence of PilO, an enzyme whose coding sequence is in the same operon as pilA, the pilin structural gene (2).The first discovered examples of prokaryotic glycoproteins were archaeal S-layer proteins (3). Since this finding, numerous examples of protein glycosylation in eubacteria have been identified (4 -8), indicating that this protein modification is distributed among all of the biological kingdoms. Proteins destined for glycosylation may be modified at a single or multiple sites along the peptide chain (7,8) in which the glycan may be one sugar or an assortment of diverse saccharides. Oligosaccharide assembly can take place either by sequential sugar addition to the target protein or by synthesis prior to glycosylation in which the entire pre-formed glycan is transferred as a single unit (7,8). Numerous protein/sugar linkages have been characterized involving many functional groups present on peptide chains and most of the commonly encountered monosaccharide moieties (8), in addition to exotic prokaryotic sugars such as bacillosamine, pseudaminic acid, and derivatives (7). Carbohydrates in eukaryotes and prokaryotes, alike, are usually bound to th...

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Section: Discussionmentioning

confidence: 99%

Glycosylation Substrate Specificity of Pseudomonas aeruginosa 1244 Pilin

Horzempa

Comer

Davis

et al. 2006

Journal of Biological Chemistry

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“…The residue to which the strain 1244 glycan is covalently attached is immediately adjacent to the type IV pilin-specific disulfide loop (DSL) region, a structure important in host glycolipid-specific binding (40). Lee et al (27) showed that the DSL is at least partially buried in the outer protein layer of the pilus shaft and is only surface exposed at the fiber tip. These results suggest that the pilin glycan might also not be present at the fiber surface or be surface expressed only at the pilus tip.…”

mentioning

confidence: 99%

Influence of Pilin Glycosylation on Pseudomonas aeruginosa 1244 Pilus Function

et al. 2005

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The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of nosocomial pneumonia. Among its virulence factors, the type IV pili of P. aeruginosa strain 1244 contain a covalently linked, three-sugar glycan of previously unknown significance. The work described in this paper was carried out to determine the influence of the P. aeruginosa 1244 pilin glycan on pilus function, as well as a possible role in pathogenesis. To accomplish this, a deletion was introduced into the pilO gene of this organism. The isogenic knockout strain produced, 1244G7, was unable to glycosylate pilin but could produce pili normal in appearance and quantity. In addition, this strain had somewhat reduced twitching motility, was sensitive to pilus-specific bacteriophages, and could form a normal biofilm. Analysis of whole cells and isolated pili from wild-type P. aeruginosa strain 1244 by transmission electron microscopy with a glycan-specific immunogold label showed that this saccharide was distributed evenly over the fiber surface. The presence of the pilin glycan reduced the hydrophobicity of purified pili as well as whole cells. With regard to pathogenicity, P. aeruginosa strains producing glycosylated pili were commonly found among clinical isolates and particularly among those strains isolated from sputum. Competition index analysis using a mouse respiratory model comparing strains 1244 and 1244G7 indicated that the presence of the pilin glycan allowed for significantly greater survival in the lung environment. These results collectively suggest that the pilin glycan is a significant virulence factor and may aid in the establishment of infection.

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“…22 Pili, however, have considerable antigenic variation between strains. 24 Bacteria also possess an array of other virulence factors, including nonpilus adhesins. 25 Some clinical isolates of P. aeruginosa from keratitis are reportedly nonpiliated.…”

Section: Pathogenesismentioning

confidence: 99%

Management of bacterial keratitis: beyond exorcism towards consideration of organism and host factors

O’Brien

2003

Eye

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Mapping the surface regions of Pseudomonas aeruginosa PAK pilin: the importance of the C‐terminal region for adherence to human buccal epithelial cells

Cited by 59 publications

References 32 publications

Glycosylation Substrate Specificity of Pseudomonas aeruginosa 1244 Pilin

Glycosylation Substrate Specificity of Pseudomonas aeruginosa 1244 Pilin

Influence of Pilin Glycosylation on Pseudomonas aeruginosa 1244 Pilus Function

Management of bacterial keratitis: beyond exorcism towards consideration of organism and host factors

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