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Pyocin S5 Import into Pseudomonas aeruginosa Reveals a Generic Mode of Bacteriocin Transport.

ABSTRACT: Pyocin S5 (PyoS5) is a potent protein bacteriocin that eradicates the human pathogen Pseudomonas aeruginosa in animal infection models, but its import mechanism is poorly understood. Here, using crystallography, biophysical and biochemical analyses, and live-cell imaging, we define the entry process of PyoS5 and reveal links to the transport mechanisms of other bacteriocins. In addition to its C-terminal pore-forming domain, elongated PyoS5 comprises two novel tandemly repeated kinked 3-helix bundle domains that structure-based alignments identify as key import domains in other pyocins. The central domain binds the lipid-bound common polysaccharide antigen, allowing the pyocin to accumulate on the cell surface. The N-terminal domain binds the ferric pyochelin transporter FptA while its associated disordered region binds the inner membrane protein TonB1, which together drive import of the bacteriocin across the outer membrane. Finally, we identify the minimal requirements for sensitizing Escherichia coli toward PyoS5, as well as other pyocins, and suggest that a generic pathway likely underpins the import of all TonB-dependent bacteriocins across the outer membrane of Gram-negative bacteria.IMPORTANCE Bacteriocins are toxic polypeptides made by bacteria to kill their competitors, making them interesting as potential antibiotics. Here, we reveal unsuspected commonalities in bacteriocin uptake pathways, through molecular and cellular dissection of the import pathway for the pore-forming bacteriocin pyocin S5 (PyoS5), which targets Pseudomonas aeruginosa In addition to its C-terminal pore-forming domain, PyoS5 is composed of two tandemly repeated helical domains that we also identify in other pyocins. Functional analyses demonstrate that they have distinct roles in the import process. One recognizes conserved sugars projected from the surface, while the other recognizes a specific outer membrane siderophore transporter, FptA, in the case of PyoS5. Through engineering of Escherichia coli cells, we show that pyocins can be readily repurposed to kill other species. This suggests basic ground rules for the outer membrane translocation step that likely apply to many bacteriocins targeting Gram-negative bacteria.

SUBMITTER: Behrens HM

PROVIDER: S-EPMC7064778 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Pyocin S5 Import into Pseudomonas aeruginosa Reveals a Generic Mode of Bacteriocin Transport.

Behrens Hannah M HM Lowe Edward D ED Gault Joseph J Housden Nicholas G NG Kaminska Renata R Weber T Moritz TM Thompson Catriona M A CMA Mislin Gaëtan L A GLA Schalk Isabelle J IJ Walker Daniel D Robinson Carol V CV Kleanthous Colin C

mBio 20200310 2

Pyocin S5 (PyoS5) is a potent protein bacteriocin that eradicates the human pathogen <i>Pseudomonas aeruginosa</i> in animal infection models, but its import mechanism is poorly understood. Here, using crystallography, biophysical and biochemical analyses, and live-cell imaging, we define the entry process of PyoS5 and reveal links to the transport mechanisms of other bacteriocins. In addition to its C-terminal pore-forming domain, elongated PyoS5 comprises two novel tandemly repeated kinked 3-h ...[more]

PMID: 32156826

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Project description:Factor for inversion stimulation (Fis) is a versatile DNA binding protein that plays an important role in coordinating bacterial global gene expression in response to growth phases and environmental stresses. Previously, we demonstrated that Fis regulates the type III secretion system (T3SS) in Pseudomonas aeruginosa In this study, we explored the role of Fis in the antibiotic resistance of P. aeruginosa and found that mutation of the fis gene increases the bacterial susceptibility to ciprofloxacin. We further demonstrated that genes related to pyocin biosynthesis are upregulated in the fis mutant. The pyocins are produced in response to genotoxic agents, including ciprofloxacin, and the release of pyocins results in lysis of the producer cell. Thus, pyocin biosynthesis genes sensitize P. aeruginosa to ciprofloxacin. We found that PrtN, the positive regulator of the pyocin biosynthesis genes, is upregulated in the fis mutant. Genetic experiments and electrophoretic mobility shift assays revealed that Fis directly binds to the promoter region of prtN and represses its expression. Therefore, our results revealed novel Fis-mediated regulation on pyocin production and bacterial resistance to ciprofloxacin in P. aeruginosa IMPORTANCE Pseudomonas aeruginosa is an important opportunistic pathogenic bacterium that causes various acute and chronic infections in human, especially in patients with compromised immunity, cystic fibrosis (CF), and/or severe burn wounds. About 60% of cystic fibrosis patients have a chronic respiratory infection caused by P. aeruginosa The bacterium is intrinsically highly resistant to antibiotics, which greatly increases difficulties in clinical treatment. Therefore, it is critical to understand the mechanisms and the regulatory pathways that are involved in antibiotic resistance. In this study, we elucidated a novel regulatory pathway that controls the bacterial resistance to fluoroquinolone antibiotics, which enhances our understanding of how P. aeruginosa responds to ciprofloxacin.

Dataset Information

Pyocin S5 Import into Pseudomonas aeruginosa Reveals a Generic Mode of Bacteriocin Transport.

Publications

Pyocin S5 Import into Pseudomonas aeruginosa Reveals a Generic Mode of Bacteriocin Transport.

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