Pectocin M1 (PcaM1) Inhibits Escherichia coli Cell Growth and Peptidoglycan Biosynthesis through Periplasmic Expression

Chérier, Dimitri; Giacomucci, Sean; Patin, Delphine; Bouhss, Ahmed; Touzé, Thierry; Blanot, Didier; Mengin‐Lecreulx, Dominique; Barreteau, Hélène

doi:10.3390/antibiotics5040036

Cited by 7 publications

(10 citation statements)

References 33 publications

(74 reference statements)

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“…It should be pointed out that deviations from the prototypical catalytic ColM motif do not necessarily preclude bacteriocin functionality (30). In line with this, it was recently found that the pectobacterial ColM-type bacteriocin pectocin M1 and a mutant form with a modified catalytic motif both provoke cellular lysis when expressed in the periplasm of E. coli (48). By demonstrating that only the pectocin M1 wild type retains lipid II degradation activity, this study indicates that toxicity exerted by the ColM module may be more complex than merely enzymatic, as initially thought.…”

Section: Discussionmentioning

confidence: 78%

A Natural ChimericPseudomonasBacteriocin with Novel Pore-Forming Activity Parasitizes the Ferrichrome Transporter

Ghequire

Kemland

Anoz-Carbonell

et al. 2017

mBio

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Modular bacteriocins represent a major group of secreted protein toxins with a narrow spectrum of activity, involved in interference competition between Gram-negative bacteria. These antibacterial proteins include a domain for binding to the target cell and a toxin module at the carboxy terminus. Self-inhibition of producers is provided by coexpression of linked immunity genes that transiently inhibit the toxin’s activity through formation of bacteriocin-immunity complexes or by insertion in the inner membrane, depending on the type of toxin module. We demonstrate strain-specific inhibitory activity for PmnH, a Pseudomonas bacteriocin with an unprecedented dual-toxin architecture, hosting both a colicin M domain, potentially interfering with peptidoglycan synthesis, and a novel colicin N-type domain, a pore-forming module distinct from the colicin Ia-type domain in Pseudomonas aeruginosa pyocin S5. A downstream-linked gene product confers PmnH immunity upon susceptible strains. This protein, ImnH, has a transmembrane topology similar to that of Pseudomonas colicin M-like and pore-forming immunity proteins, although homology with either of these is essentially absent. The enhanced killing activity of PmnH under iron-limited growth conditions reflects parasitism of the ferrichrome-type transporter for entry into target cells, a strategy shown here to be used as well by monodomain colicin M-like bacteriocins from pseudomonads. The integration of a second type of toxin module in a bacteriocin gene could offer a competitive advantage against bacteria displaying immunity against only one of both toxic activities.

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Section: Discussionmentioning

confidence: 78%

A Natural ChimericPseudomonasBacteriocin with Novel Pore-Forming Activity Parasitizes the Ferrichrome Transporter

Ghequire

Kemland

Anoz-Carbonell

et al. 2017

mBio

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“…S1 ). In support of that, it was previously suggested that lytic activity of pectocin M1, when expressed in E. coli and secreted to the periplasm, does not require FkpA for killing ( 29 ). It cannot be excluded, however, that in some species another chaperone(s) provides assistance in activity-generating folding.…”

Section: Perspectivementioning

confidence: 70%

“…For this protein, phosphatase activity via a lipid II hydrolase assay remains to be assessed ( 20 ). Interestingly, even in a mutated pectocin M1 protein where lipid II degradation is abolished, the ColM module may still provoke cellular lysis when secreted to the periplasm, indicating that inhibition by ColM domains may not be based solely on the known catalytic activity ( 29 ). This is reminiscent of the collateral damage to membranes and membrane-bound complexes that can be caused by lipid II-binding antibiotics ( 16 ).…”

Section: Perspectivementioning

confidence: 99%

The ColM Family, Polymorphic Toxins Breaching the Bacterial Cell Wall

Ghequire

Buchanan

Mot

2018

mBio

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Bacteria host an arsenal of antagonism-mediating molecules to combat for ecologic space. Bacteriocins represent a pivotal group of secreted antibacterial peptides and proteins assisting in this fight, mainly eliminating relatives. Colicin M, a model for peptidoglycan-interfering bacteriocins in Gram-negative bacteria, appears to be part of a set of polymorphic toxins equipped with such a catalytic domain (ColM) targeting lipid II. Diversifying recombination has enabled parasitism of different receptors and has also given rise to hybrid bacteriocins in which ColM is associated with another toxin module. Remarkably, ColM toxins have recruited a diverse array of immunity partners, comprising cytoplasmic membrane-associated proteins with different topologies. Together, these findings suggest that different immunity mechanisms have evolved for ColM, in contrast to bacteriocins with nuclease activities.

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“…Colicin M and recently identified orthologs from Pseudomonas and Pectobacterium species form a unique family of bacteriocins interfering with the integrity of the cell wall by enzymatic degradation of peptidoglycan lipid intermediates (8,9,26). They exert their deleterious activity in the periplasm of the targeted cells, i.e., in the compartment where the peptidoglycan lipid II precursor is translocated and where it remains transiently accessible before being used for polymerization steps by the penicillin-binding proteins.…”

Section: Discussionmentioning

confidence: 99%

“…tomato DC3000, and P. fluorescens Q8r1-96 strains, and the corresponding proteins, named PaeM, PsyM, and PflM, respectively, were purified and their lipid II-degrading activity was characterized (6). Two other members of the same family were also identified in Pectobacterium carotovorum (7,8). The homology between these different proteins was mainly observed in the second half of the protein sequence which corresponds to the enzymatic activity domain.…”

mentioning

confidence: 99%

Impact of FiuA Outer Membrane Receptor Polymorphism on the Resistance of Pseudomonas aeruginosa toward Peptidoglycan Lipid II-Targeting PaeM Pyocins

et al. 2019

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Certain Pseudomonas aeruginosa strains produce a homolog of colicin M, namely, PaeM, that specifically inhibits peptidoglycan biosynthesis of susceptible P. aeruginosa strains by hydrolyzing the lipid II intermediate precursor. Two variants of this pyocin were identified whose sequences mainly differed in the N-terminal protein moiety, i.e., the region involved in the binding to the FiuA outer membrane receptor and translocation into the periplasm. The antibacterial activity of these two variants, PaeM1 and PaeM2, was tested against various P. aeruginosa strains comprising reference strains PAO1 and PA14, PaeM-producing strains, and 60 clinical isolates. Seven of these strains, including PAO1, were susceptible to only one variant (2 to PaeM1 and 5 to PaeM2), and 11 were affected by both. The remaining strains, including PA14 and four PaeM1 producers, were resistant to both variants. The differences in the antibacterial spectra of the two PaeM homologs prompted us to investigate the molecular determinants allowing their internalization into P. aeruginosa cells, taking the PAO1 strain that is susceptible to PaeM2 but resistant to PaeM1 as the indicator strain. Heterologous expression of fiuA gene orthologs from different strains into PAO1, site-directed mutagenesis experiments, and construction of PaeM chimeric proteins provided evidence that the cell susceptibility and discrimination differences between the PaeM variants resulted from a polymorphism of both the pyocin and the outer membrane receptor FiuA. Moreover, we found that a third component, TonB1, a protein involved in iron transport in P. aeruginosa, working together with FiuA and the ExbB/ExbD complex, was directly implicated in this discrimination. IMPORTANCE Bacterial antibiotic resistance constitutes a threat to human health, imposing the need for identification of new targets and development of new strategies to fight multiresistant pathogens. Bacteriocins and other weapons that bacteria have themselves developed to kill competitors are therefore of great interest and a valuable source of inspiration for us. Attention was paid here to two variants of a colicin M homolog (PaeM) produced by certain strains of P. aeruginosa that inhibit the growth of their congeners by blocking cell wall peptidoglycan synthesis. Molecular determinants allowing recognition of these pyocins by the outer membrane receptor FiuA were identified, and a receptor polymorphism affecting the susceptibility of P. aeruginosa clinical strains was highlighted, providing new insights into the potential use of these pyocins as an alternative to antibiotics.

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Pectocin M1 (PcaM1) Inhibits Escherichia coli Cell Growth and Peptidoglycan Biosynthesis through Periplasmic Expression

Cited by 7 publications

References 33 publications

A Natural ChimericPseudomonasBacteriocin with Novel Pore-Forming Activity Parasitizes the Ferrichrome Transporter

A Natural ChimericPseudomonasBacteriocin with Novel Pore-Forming Activity Parasitizes the Ferrichrome Transporter

The ColM Family, Polymorphic Toxins Breaching the Bacterial Cell Wall

Impact of FiuA Outer Membrane Receptor Polymorphism on the Resistance of Pseudomonas aeruginosa toward Peptidoglycan Lipid II-Targeting PaeM Pyocins

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