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Cyclic lipoundecapeptide amphisin from Pseudomonas sp. strain DSS73
D Sørensen1, T H Nielsen, C Christophersen
1Marine Chemistry Section, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
Summary
The crystal structure of amphisin, a Pseudomonas lipopeptide, reveals a helical conformation. This amphiphilic molecule exhibits significant biosurfactant and antifungal properties.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Amphisin is a lipoundecapeptide produced by non-ribosomal biosynthesis in Pseudomonas sp. strain DSS73.
- It shares structural similarities with other cyclic lipopeptides like tensin and pholipeptin.
Purpose of the Study:
- To determine the high-resolution crystal structure of amphisin.
- To elucidate the structural basis for its amphiphilic nature and biological activities.
Main Methods:
- X-ray crystallography was used to solve the crystal structure of amphisin tetrahydrate.
- The structure was determined to a resolution of 0.65 Å.
Main Results:
- The primary structure of amphisin was identified as beta-hydroxydecanoyl-D-Leu-D-Asp-D-allo-Thr-D-Leu-D-Leu-D-Ser-L-Leu-D-Gln-L-Leu-L-Ile-L-Asp.
- Amphisin forms a lactone ring, linking Thr4 O(gamma) to the C-terminus.
- The molecule adopts a predominantly 3(10)-helical structure, with the cyclic peptide encircling a water molecule.
Conclusions:
- The determined structure provides detailed insights into the molecular organization of amphisin.
- The amphiphilic and helical nature of amphisin likely contributes to its observed biosurfactant and antifungal properties.