|Original publication||Vallet-Gely, 2010|
|Original source||Pseudomonas entomophila L48|
|Other known sources (non-putative)||Pseudomonas sp. COR5 (Oni, 2019)|
|Stereochemistry determined by||n.d.|
|Molecular weight||1720.0 g/mol|
|Mono-isotopic mass||1721.1150 Da|
|Solubility||MeOH, acetonitrile/water, DMF|
|Minimal surface tension||n.d.|
|NMR data available in literature||DMF-d7 (Oni, 2019)|
Entolysin was first named in a study into the entomopathogenic (insecticidal) properties of its producing bacterium, P. entomophila L48. However, though entolysin is required for swarming motility, as described for other lipopeptides, it does not participate in the virulence of P. entomophila for Drosophila melanogaster. Two homologues (entolysin A and B) were described, though their structural difference could not yet be established. In subsequent studies, the structure of entolysin A could be elucidated, while that of entolysin B remains elusive.
Structure determination of entolysin A and B, as extracted from Pseudomonas entomophila L48, was performed by amino acid analysis and mass spectrometry (MALDI MS/MS). The characterization of the fatty acid was performed separately by gas chromatography and showed the presence of a 3-hydroxy decanoic acid (3-OH C10:0) for both compounds. Amino acid analysis revealed the presence of 4x Leu and 1x Ile. However, using mass spectrometry, the authors were unable to discriminate these amino acids in the sequence, as they possess the same molecular weight. Consequently, the structures were determined to possess either leucine or isoleucine at certain positions in the amino acid chain. Moreover, it was found that both entolysin A and B possess an identical mass and amino acid sequence and thus, the authors were unable to pinpoint the structural difference between both compounds. Therefore, it was concluded that entolysin A and B are likely isoforms, where the positions of leucine and isoleucine differs. The stereochemistry of entolysin A was characterized by phylogenetic analysis of the amino acid sequences of C domains of the non-ribosomal peptide synthetases. (Vallet-Gely, 2010)
In a subsequent analysis, Bode et al. used labeling experiments with deuterated [2H9]leucine followed by tandem MS analysis to determine a corrected peptide sequence of entolysin A. (Bode, 2012) Later, NMR showed an identical structure for entolysin A, as produced by Pseudomonas sp. COR5. (Oni, 2019)
Taking all this data together, the structure of entolysin A is 3-OH C10:0 – D-Leu1 – D-Glu2 – D-Gln3 – D-Val4 – D-Leu5 – D-Gln6 – D-Val7 – D-Leu8 – D-Gln9 – D-Ser10 – L-Val11 – L-Leu12 – D-Ser13 – L-Ile14 whereby its macrocycle is formed by an ester bond between the C-terminal carbonyl and the hydroxyl side chain of Ser10. The structure of entolysin B was not characterized in more detail, and its characterization remains incomplete.
Entolysin appears to be essential for swarming motility of its producing organism (P. entomophilia L48) as was observed with many other Pseudomonas-produced CLiPs. (Vallet-Gely, 2010)
There is some debate concerning the antifungal activity of entolysin. More specifically, both wild-type and entolysin-deficient mutant are both able to inhibit the growth of Pythium ultimum, indicating that entolysin is not responsible for the biocontrol activity of its producing strain (P. entomophila L48) (Vallet-Gely, 2010). In contrast, pure entolysin A caused growth inhibition of Pythium myriotylum and interacted with its mycelia to cause either extensive branching or lysis. (Oni, 2019)
Finally, while the entolysin-producing P. entomophila L48 is able to infect and kill Drosophila melanogaster upon ingestion, the CLP entolysin itself does not appear to participate in its virulence. (Vallet-Gely, 2010)
Mode of action
The antibacterial properties of entolysin B were independent of the presence of calcium. (Reder-Christ, 2012). No further investigations into the mode of action of entolysin were performed.
NMR fingerprint data
Recently, it was established that the planar structure and stereochemistry of CLiPs can be assessed by simple comparison to a reference. (De Roo, 2022) More specifically, by matching NMR spectra of a CLiP from a newly isolated bacterial source with those of existing (reference) CLiPs, one can determine whether they are identical or not. A detailed explanation on what NMR fingerprint matching is, and how to use it, can be found here.
Below, we provide the reference NMR data of entolysin A in various formats. This data is recorded in DMF-d7 at room temperature, and can be used to asses similarities of newly isolated CLiPs to entolysin A.
Bode, et al. “Determination of the absolute configuration of peptide natural products by using stable isotope labeling and mass spectrometry.” Chemistry – A European Journal18, 8 (2012): https://dx.doi.org/10.1002/chem.201103479.
De Roo, et al. “An Nuclear Magnetic Resonance Fingerprint Matching Approach for the Identification and Structural Re-Evaluation of Pseudomonas Lipopeptides.” Microbiology Spectrum10, 4 (2022): https://dx.doi.org/doi:10.1128/spectrum.01261-22.
Oni, et al. “Fluorescent Pseudomonas and cyclic lipopeptide diversity in the rhizosphere of cocoyam (Xanthosoma sagittifolium).” Environmental Microbiology (2019): https://dx.doi.org/doi:10.1111/1462-2920.14520.
Reder-Christ, et al. “Model membrane studies for characterization of different antibiotic activities of lipopeptides from Pseudomonas.” Biochimica et Biophysica Acta – Biomembranes1818, 3 (2012): https://dx.doi.org/10.1016/j.bbamem.2011.08.007.
Vallet-Gely, et al. “Association of hemolytic activity of Pseudomonas entomophila, a versatile soil bacterium, with cyclic lipopeptide production.” Applied and Environmental Microbiology76, 3 (2010): https://dx.doi.org/10.1128/AEM.02112-09.