Background: Pathogenic Pseudomonas aeruginosa strains produce a colicin M-like bacteriocin exhibiting peptidoglycan lipid II-degrading activity. Results: We have determined the crystal structure of the Pseudomonas aeruginosa PaeM bacteriocin and functionally characterized its C-terminal activity domain.
Conclusion:This study highlights structural plasticity of the active site of this enzyme family. Significance: The PaeM pyocin could potentially be exploited as antibacterial agent.
Streptococcus equi is a horse pathogen belonging to Lancefield group C. Infection by S. equi ssp. equi causes strangles, a serious and highly contagious disease of the upper respiratory tract. F I . FNE lacks the canonical Fn-binding peptide repeats observed in many microbial surface components recognizing adhesive matrix molecules. We found that the interaction between FNE and the human GBD is mediated by the binding of the disordered Cterminal region (residues 208-262) of FNE to the 789 F I GBD subfragment. The crystal structure of FNE showed that it is similar to the minor pilus protein Spy0125 of Streptococcus pyogenes, found at the end of pilus polymers and responsible for adhesion. FNE and Spy0125 both have a superimposable internal thioester bond between highly conserved Cys and Gln residues. Small-angle X-ray scattering of the FNE-789 F I complex provided a model that aligns the C-terminal peptide of FNE with the E-strands of the F I domains, adopting the b-zipper extension model observed in previous structures of microbial surface components recognizing adhesive matrix molecule adhesion peptides bound to F I domains.
DatabaseThe coordinates of the FNE-aREP3 complex have been deposited at the Protein Data Bank under the code 4PFG.
Structured digital abstract• GBD and FNE bind by isothermal titration calorimetry (View interaction)• GBD 789FI and FNE bind by isothermal titration calorimetry (View interaction)• FNE-CT and GBD 789FI bind by isothermal titration calorimetry (View interaction)• GBD and FNE-CT bind by isothermal titration calorimetry (View interaction)• FNE and GBD 789FI bind by molecular sieving (View interaction)• FNE-CT binds to GBD 789FI by pull down (View interaction)• FNE and GBD 789FI bind by x ray scattering (View interaction)• GBD and FNE physically interact by fluorescence polarization spectroscopy (View interaction)• collagen and GBD bind by fluorescence polarization spectroscopy (View interaction)
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