O serotype-independent susceptibility of Pseudomonas aeruginosa to lectin-like pyocins.
Bottom Line: The recombinant proteins exhibit species-specific antagonistic activities down to nanomolar concentrations against clinical and environmental P. aeruginosa strains, including several multidrug-resistant isolates.No correlation was found between L pyocin susceptibility and phylogenetic relatedness of P. aeruginosa isolates.Sensitive strains were retrieved in 13 out of 15 O serotypes tested, excluding the possibility that the highly variable and immunogenic O serotype antigen of the LPS coating would represent a dominant susceptibility-discriminating factor.
Affiliation: Centre of Microbial and Plant Genetics, University of Leuven, 3001, Heverlee, Belgium.Show MeSH
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Mentions: The MMBL domains within each P. aeruginosa tandem display pronounced sequence divergence (<28% amino acid identity; Fig. 1B), similar to previously characterized LlpAs in Pseudomonas (Ghequire et al. 2012a). This consistent domain segregation reflects a functional specialization of the MMBL modules and experimental evidence in support of this was reported for P. putida and P. protegens LlpAs (Ghequire et al. 2013a). The QxDxNxVxY motifs defining the rhamnose-binding pockets IIIC and IIC of pyoL1 are well conserved across both P. aeruginosa groups, suggesting a similar binding potential of the carboxy-terminal MMBL domain (Fig. 2). However, at sites IC, IN, and IIIN, the C1433 and BWHPSA007 groups carry quite dissimilar sequences. While the IIIN motif of the C1433 group resembles well the corresponding sequences of non-P. aeruginosa LlpAs, the reverse is true for the IN and IC motifs that are better preserved in BWHPSA007. The functional implications of this apparent group-linked motif differentiation are not clear. Sites IN and IC are not surface-exposed, excluding their involvement in the carbohydrate-binding function of the bacteriocin, and the weak binding to site IIIN is probably of little physiological significance, if any (Ghequire et al. 2013a; McCaughey et al. 2014). The highly degenerate IIN site likely lost its carbohydrate-binding potential completely in all pseudomonads.
Affiliation: Centre of Microbial and Plant Genetics, University of Leuven, 3001, Heverlee, Belgium.