Mystery Solved For How A Toxin Family Is Made | Chemical & Engineering News
Volume 90 Issue 38 | p. 26 | Concentrates
Issue Date: September 17, 2012

Mystery Solved For How A Toxin Family Is Made

Toxins are made naturally by symbiotic bacteria dwelling on a sponge
Department: Science & Technology
News Channels: Analytical SCENE, Biological SCENE
Keywords: natural products, biosysnthesis, marine sponge, ribosome

A deep dive into the DNA of a marine sponge has settled the question of where the giant natural-product toxins called polytheonamides get their start—on ribosomes of the sponge’s symbiotic bacteria, not through a nonribosomal peptide synthetase, as previously believed (Science, DOI: 10.1126/science.1226121). Researchers had thought a nonribosomal route seemed logical, because polytheonamides contain multiple unusual amino acids. However, a team led by Jörn Piel of the Swiss Federal Institute of Technology, Zurich, and the University of Bonn surmised that the large size of the polytheonamides—48 residues—pointed to a ribosomal origin. They confirmed their hunch by running the polymerase chain reaction on samples of Theonella swinhoei, a sponge that harbors a host of symbiotic microbes. They found a bacterial gene cluster encoding both a peptidic polytheonamide precursor and a suite of enzymes. With mass spectrometry, they have confirmed so far that three of the enzymes contribute to the 48 chemical transformations needed to convert the precursor into polytheonamides, including dehydration and epimerization steps. The study reveals a whole new set of modifications to ribosome-synthesized natural products, says Wilfred A. van der Donk of the University of Illinois, Urbana-Champaign. “I find this work very exciting.”

 
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