Protein secretion in Pseudomonas aeruginosa

Lipase from &x4domonas ueruginosu is a M, 29 kDa protein with a single functional disultide bond as shown by a shift in electrophoretic mobility after treatment with dithiothreitol and iodoacetamide. Liited proteolysis of lipase with Staphylococcus uureus protease V8 resulted in cleavage after amino acid residues Asp)' and GIu~. Comparison of the lipase amino acid sequence with those of other hydrolases with known 3D structures indicated that the folding pattern might be compatible with the al/l hydrolase fold, thereby allowing us to construct a 3D model which fitted the biochemical properties. The model predicts a catalytic triad consisting of Se?, Asp*" and Hi?', and contains a disuhide bond connecting residues Cys'S) and C~S*~~. Residues Asp3* and Gl@ are located at the surface of the enzyme, whereas the disulfide bond is rather inaccessible, which is in agreement with the finding that the protein needed to be partly unfolded before a reduction of the disultide bond could take place. A striking prediction from the model was the lack of a lid-like a-helical loop structure covering the active site which confers to other well-characterized lipases a unique property known as interfacial activation. Experimental determination of lipase activity under conditions where the substrate existed either as monomeric solutions or aggregates confirmed the absence of interfacial activation.

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“…cated at the end of /I-strand 2 and appears to be easily ue~gi~sa secretory proteins [34]. strand 3 which is not completely surface-exposed.…”

Section: Discussionmentioning

confidence: 99%

Topological characterization and modeling of the 3D structure of lipase from Pseudomonas aeruginosa

et al. 1993

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“…These include Erwinia species (secretion of enzymes which degrade the plant cell wall) (He et al, 1991;~ondemine et al, 1992;Lindeberg and eollmer, 1992;Reeves et al, 1993), Xanthomonas campestris (secretion of a range of extracellular enzymes, including pectate Iyases and cellulases) (Dums et al, 1991, Hu et al, 1992, and the opportunistic animal pathogens Aeromonas hydrophila (secretion of the toxin aerolysin and other proteins) (Jiang and Howard , 1992) and P. aeruginosa (secretion of numerous proteins, including elastase, alkaline phosphatase, phospholipase e, and exotoxin A) (Lazdunski et al, 1990;Bally et al, 1991 ;Filloux et al, 1991 ;Nunn and Lory, 1992;Tommassen et al, 1992: Akrim et aI., 1993. Recently it has been shown (Sandkvist et al, 1993) that secretion of cholera toxin by V. cholerae requires a gene, epsE, which is a homologue of pulE (Martin et al, 1993).…”

Section: Protein Secretionmentioning

confidence: 99%

Common components in the assembly of type 4 fimbriae, DNA transfer systems, filamentous phage and protein‐secretion apparatus: a general system for the formation of surface‐associated protein complexes

Hobbs

Mattick

1993

Molecular Microbiology

361

286

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Summary The Pseudomonas aeruginosa genes pilB‐D and pilQ are necessary for the assembly of type 4 fimbriae. Homologues of these genes and of the subunit (pilin) gene have been described in various different bacterial species, but not always in association with type 4 fimbrial biosynthesis and function. Pil‐like proteins are also involved in protein secretion, DNA transfer by conjugation and transformation, and morphogenesis of filamentous bacteriophages. It seems likely that the Pil homologues function in the processing and export of proteins resembling type 4 fimbrial sub‐units, and in their organization into fimbrial‐like structures. These may either be true type 4 fimbriae, or components of protein complexes which act in the transport of macromolecules (DNA or protein) into or out of the cell. Some PilB‐like and PilQ‐like proteins are apparently also involved in the assembly of non‐type 4 polymeric structures (filamentous phage virions and conjugative pili). The diverse studies summarized in this review are providing insight into an extensive infrastructural system which appears to be utilized in the formation of a variety of cell surface‐associated complexes.

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“…P. aeruginosa has developed highly sophisticated virulence mechanisms and secretes a wide range of extracellular virulence factors, such as proteases (50), exotoxin A (53), rhamnolipids (23), pyocyanin (24), and siderophores (11). Production of these virulence factors is regulated to a large extent by a cell density-dependent gene regulatory mechanism termed quorum sensing (QS) (35).…”

mentioning

confidence: 99%

Anaerobiosis-Induced Loss of Cytotoxicity Is Due to Inactivation of Quorum Sensing in Pseudomonas aeruginosa

et al. 2011

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Pseudomonas aeruginosa, an opportunistic pathogen of clinical importance, causes chronic airway infections in patients with cystic fibrosis (CF). Current literature suggests that pockets with reduced oxygen tension exist in the CF airway mucus. However, virulence features of this opportunistic pathogen under such conditions are largely unknown. Cell-free supernatant of the standard laboratory P. aeruginosa strain PAO1 obtained from anaerobic culture, but not aerobic culture, failed to kill A549 human airway epithelial cells. Further investigation revealed that this reduced cytotoxicity upon anaerobiosis was due to the suppressed secretion of elastase, a virulence factor controlled by P. aeruginosa quorum sensing (QS). Both a lacZ-reporter fusion assay and quantitative real-time PCR (RT-PCR) analysis demonstrated that transcription of the elastase-encoding lasB gene was substantially decreased during anaerobic growth compared with aerobic growth. Moreover, transcription of other genes controlled by the LasI/R QS system, such as rhlR, vqsR, mvfR, and rsaL, was also repressed under the same anaerobic growth conditions. Importantly, synthesis of 3-oxo-C 12 -HSL (PAI-1), an autoinducer molecule that mediates induction of the LasI/R QS system, was >22-fold decreased during anaerobic growth while C 4 -HSL (PAI-2), which mediates RhlI/R QS, was nondetectable under the same growth conditions. Transcription of the lasB gene was restored by exogenous supplementation with autoinducers, with PAI-2 more effective than PAI-1 or Pseudomonas quinolone signal (PQS) at restoring transcription of the lasB gene. Together, these results suggest that anaerobiosis deprives P. aeruginosa of the ability to regulate its virulence via QS and this misregulation attenuates the pathogenic potential of this important pathogen.

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Protein secretion in Pseudomonas aeruginosa

Cited by 98 publications

References 99 publications

Topological characterization and modeling of the 3D structure of lipase from Pseudomonas aeruginosa

Topological characterization and modeling of the 3D structure of lipase from Pseudomonas aeruginosa

Common components in the assembly of type 4 fimbriae, DNA transfer systems, filamentous phage and protein‐secretion apparatus: a general system for the formation of surface‐associated protein complexes

Anaerobiosis-Induced Loss of Cytotoxicity Is Due to Inactivation of Quorum Sensing in Pseudomonas aeruginosa

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