Tensin

General info

Original publication	Hendriksen, 2000, Nielsen, 2000
Original source	Pseudomonas fluorescens 96.578
Sequence determined by	NMR spectroscopy and mass spectrometry
Stereochemistry determined by	X-ray crystallography
Other known sources (non-putative)	Pseudomonas sp. FhG100052 (Marner, 2020) Pseudomonas  zeae OE 48.2 (Girard, 2021)

Chemical properties

Molecular formula	C67H116N12O20
Mono-isotopic mass	1394. 8272 Da
Molecular weight	1395.7 g/mol
Solubility	DMSO, DMF, acetone, methanol
CMC	n.a.
NMR chemical shifts available	Acetone-d6 (Marner, 2020) DMF-d7 (Girard, 2021)

Structure

Originally, the structure and absolute configuration of tensin was primarily determined by means of X-ray crystallography. (Hendriksen, 2000) The primary structure of tensin is 3-OH C10:0 – D-Leu1 – D-Asp2 – D-aThr3 – D-Leu4 – D-Leu5 – D-Ser6 – L-Leu7 – D-Gln8 – L-Leu9 – L-Ile10 – L-Glu11. The presence of an ester bond cyclized the molecule between the C-terminal carbonyl and the side chain hydroxyl moiety of Thr3.

Later, tensin was also extracted from a novel source (Pseudomonas sp. FhG100052), and analysed by means of NMR spectroscopy, MS/MS and Marfey’s analysis. Minor compounds produced by this bacterium –due to A-domain substrate flexibility – are named stechlisins. These structurally similar compounds differ from tensin in their fatty acid tail length or amino acid identity. Very recently, another tensin producer was isolated (Pseudomonas  zeae OE 48.2^T) and characterized by means of NMR spectroscopy. (Girard, 2021) Here, the stereochemistry of tensin was elucidated by using an NMR fingerprint matching approach.

Tensin is a member of the amphisin group, a collection of structurally similar lipopeptides including amphisin, arthrofactin, lokisin, anikasin, milkisins and stechlisins. The group is also reported to contain two ill-characterized CLiPs: hordersin and pholipeptin. Within the amphisin group, variations occur at position 8 (Gln vs. Ser), position 9 (Leu vs Ile) and position 11 (Asp vs Glu). Tensin is isobaric to other amphisin group members such as milkisin.

Bioactivity

Tensin is able to inhibit growth of fungi (Pythium ultimum and Rhizoctonia solani) (Nielsen, 2002). Additionally, it possesses an antagonistic activity against the Gram-negative bacterium Moraxella catarrhalis FH6810. No information is available on antagonistic activities against other microorganisms.

Physicochemical properties

Most of the CLiPs produced by Pseudomonas species are able to reduce the surface tension of growth media to different extents. In this respect, tensin reduces the surface tension of water from 75 mN.m^-1 to ~27 mN.m^-1 (Nielsen, 2002).

Three-dimensional structure

The three-dimensional structure of tensin was determined by X-ray crystallography. (Hendriksen, 2000) Similar to other Pseudomonas CLiPs, tensin features a left-handed α-helix ranging between D-Leu1 and D-Ser6. The helix is followed by a so-called loop, a rigid structure without defined secondary structure that allows to fold the C-terminal end back to the middle of the helix, where cyclization occurs. Consequently, part of the helix is exocyclic, while part of it is contained within the macrocycle. Furthermore, the conformation is such that there is a clear separation between the polar and hydrophobic residues. This leads to the presence of both a hydrophobic and hydrophilic side on the molecular surface, leading to an amphipathic molecule, in agreement with its function of a biosurfactant.

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 tensin A. This data is recorded in DMF-d7 at room temperature, and can be used to asses similarities of newly isolated CLiPs to tensin A.

References

De Roo, et al. “An nuclear magnetic resonance fingerprint matching approach for the identification and structural re-evaluation of Pseudomonas lipopeptides.” Microbiology Spectrum
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.

Hendriksen, et al. “Cyclic lipoundecapeptide tensin from Pseudomonas fluorescens strain 96.578.” Acta Crystallographica Section CC56 (2000).

Marner, et al. “Molecular Networking-Guided Discovery and Characterization of Stechlisins, a Group of Cyclic Lipopeptides from a Pseudomonas sp.” J Nat Prod83, 9 (2020): https://dx.doi.org/10.1021/acs.jnatprod.0c00263.

Nielsen, et al. “Antibiotic and biosurfactant properties of cyclic lipopeptides produced by fluorescent Pseudomonas spp. from the sugar beet rhizosphere.” Applied and Environmental Microbiology68, 7 (2002): https://dx.doi.org/10.1128/aem.68.7.3416-3423.2002.

Nielsen, et al. “Structure, production characteristics and fungal antagonism of Tensin – A new antifungal cyclic lipopeptide from Pseudomonas fluorescens strain 96-578.” Journal of Applied Microbiology898 (2000).
https://dx.doi.org/ https://doi.org/10.1046/j.1365-2672.2000.01201.x