|Original publication||Li, 2013|
|Original source||Pseudomonas mosselii BW11M1|
|Other known sources (non-putative)||Pseudomonas sp. COR51 (Oni, 2019) |
Pseudomonas sp. RtlB026 (Uchiyama, 2021)
Pseudomonas sp. 250J (Molina-Santiago, 2015)
Pseudomonas xantholysinigenes RW9S1AT (Girard, 2021)
Pseudomonas sp. DJ15 (Lim, 2017) (no stereochemistry determined)
|Stereochemistry determined by||Total synthesis: Pseudomonas mosselii BW11M1 (Li, 2013)|
NMR spectral matching: Pseudomonas sp. COR51, Pseudomonas sp. RtlB026, Pseudomonas sp. 250J (De Roo, 2022)
|Molecular weight||1776.2 g/mol|
|Mono-isotopic mass||1775.0808 Da|
|Solubility||Methanol, chloroform, acetone, buffer, DMF|
Not soluble (or very limited) in milliQwater
|Minimal surface tension||n.a.|
|NMR data available in literature||DMF-d7 (Li, 2013, Oni, 2019, Girard, 2021, De Roo, 2022) |
Methanol-d4 (Molina-Santiago, 2015)
The original xantholysin-producer, Pseudomonas mosselii BW11M1 (originally Pseudomonas putida BW11M1), was isolated from the banana rhizosphere in Sri Lanka in the context of a study aimed at screening for natural compounds that display inhibitory activity against Xanthomonas bacteria. (Vlassak, 1992). By using several knock-out mutants, it was observed that the antimicrobial activity of P. mosselii BW11M1 was exerted by the cyclic lipodepsipeptide (CLiP) xantholysin. (Li, 2013) This CLiP consists of a partially cyclized 14-amino acid peptide sequence. The N-terminus of the peptide is capped by a fatty acid moiety. Since its original discovery, other non-putative xantholysin producers were isolated across the globe, including Pseudomonas sp. 250J (Molina-Santiago, 2015), Pseudomonas sp. DJ15 (Lim, 2017), Pseudomonas sp. COR51 (Oni, 2019), Pseudomonas sp. RtlB026 (Uchiyama, 2021), and Pseudomonas xantholysinigenes RW9S1AT (Girard, 2021).
Xantholysin appears to promote the surface colonization of its producing bacteria (Li, 2013, Oni, 2019) Moreover, xantholysin A displays clear antimicrobial activities against Gram-positive bacteria and fungi at micromolar concentrations. (Molina-Santiago, 2015, Oni, 2019) Interestingly, antimicrobial activity also extends to some Gram-negative strains, including several Xanthomonas species. Consequently, the general assumption that Pseudomonas CLiPs do not exert any antagonistic activities against Gram-negative bacteria should be reconsidered, as WLIP – a CLiP from the viscosin group – also shows similar activities against Xanthomonas.
Xantholysin A showed strong insecticidal activity against aphids (Myzus persicae) when topically applied at micromolar levels. (Lim, 2017) Similar insecticidal activities were also observed for orfamide A.
Finally, a compound extracted from Pseudomonas soli F-279,208T, rudimentary identified as xantholysin A, showed antiproliferative activity against a RCC4 kidney tumour cell line, while it did not cause cytotoxic effects against other human tumour cell lines including, liver, pancreas and breast tumour cell lines. (Pascual, 2014) Anticancer activities were also observed for MDN-0066 (Bananamide group) and viscosin (Viscosin group).
The structure of xantholysin A was first elucidated in 2013 by means of liquid state NMR spectroscopy and mass spectrometry. (Li, 2013) It consists of a 3-hydroxy decanoic acid (HDA) linked to a cyclic peptide consisting of 14 amino acids, of which 8 are contained in a macrocycle. The macrocycle is formed by an ester bond between the C-terminal carbonyl (L-Ile14) and the hydroxyl side chain of D-Ser7. The stereochemistry of xantholysin A was elucidated recently by means of total synthesis and NMR fingerprint matching. (De Roo, 2022) Summarizing, the chemical structure of xantholysin A is (3R-OH C10:0 – L-Leu1 – D-Glu2 – D-Gln3 – D-Val4 – D-Leu5 – L-Gln6 – D-Ser7 – D-Val8 – D-Leu9 – D-Gln10 – L-Leu11 – L-Leu12 – D-Gln13 – L-Ile14. The molecule is cyclized by means of an ester bond between the C-terminus and the side chain hydroxyl moiety of serine at position 7. The structure of xantholysin bears a single negative charge at physiological pH due to the presence of a glutamic acid at position 2.
Xantholysin A is the parental compound of the Xantholysin group, which contains the structurally similar xantholysins B – D. Within the Xantholysin group, variations occur at the level of the fatty acid, or at position 14 (Ile vs. Val).
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 xantholysin A in various formats. This data is recorded in DMF-d7 at 328K (55°C), and can be used to asses similarities of newly isolated CLiPs to xantholysin A.
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.
Girard, et al. “Transporter gene-mediated typing for detection and genome mining of lipopeptide-producing Pseudomonas.” Applied Environmental Microbiology (2021): https://dx.doi.org/10.1128/aem.01869-21.
Li, et al. “The antimicrobial compound xantholysin defines a new group of Pseudomonas cyclic lipopeptides.” PLoS One8, 5 (2013): https://dx.doi.org/10.1371/journal.pone.0062946.
Lim, et al. “Identification of lipopeptide xantholysins from Pseudomonas sp. DJ15 and their insecticidal activity against Myzus persicae.” Entomological Research47, 6 (2017): https://dx.doi.org/10.1111/1748-5967.12241.
Molina-Santiago, et al. “Efflux pump-deficient mutants as a platform to search for microbes that produce antibiotics.” Microbial Biotechnology8, 4 (2015): https://dx.doi.org/10.1111/1751-7915.12295.
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.
Pascual, et al. “Pseudomonas soli sp. nov., a novel producer of xantholysin congeners.” Systematic and Applied Microbiology37, 6 (2014): https://dx.doi.org/10.1016/j.syapm.2014.07.003.
Uchiyama, et al. “Structural revision of natural cyclic depsipeptide MA026 established by total synthesis and biosynthetic gene cluster analysis.” Angewandte Chemistry International Edition English60, 16 (2021): https://dx.doi.org/10.1002/anie.202015193.
Vlassak, et al. “Isolation and characterization of fluorescent Pseudomonas associated with the roots of rice and banana grown in Sri Lanka.” Plant and Soil145, 1 (1992): https://dx.doi.org/10.1007/BF00009541.