Differentiating 5-thiooxazoles from oxazolone-coupled thioamides in RiPP natural products
Manley, O. M.; Shriver, T. J.; Ayala, J. M.; Owen, B. C.; Ziarek, J. J.; Rosenzweig, A. C.
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Conversion of cysteine residues to 5-thiooxazole moieties by multinuclear nonheme iron-dependent oxidative enzymes (MNIOs) is a prevalent modification in ribosomally synthesized, post-translationally modified peptide (RiPP) natural products. However, this post-translational modification (PTM) is difficult to distinguish from MNIO-produced oxazolone-coupled thioamides, such as those present in the RiPP methanobactin. The RiPP virulence factor oxazolin contains six copper-binding heterocycles installed by an MNIO. Here, we reassign these PTMs, originally described as oxazolones/thioamides, as 5-thiooxazoles on the basis of detailed comparative chemical and structural characterization of oxazolin and methanobactin. These data establish a benchmark for differentiating these two PTMs in newly discovered RiPPs. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=86 SRC="FIGDIR/small/730506v1_ufig1.gif" ALT="Figure 1"> View larger version (12K): org.highwire.dtl.DTLVardef@d30435org.highwire.dtl.DTLVardef@1b933fforg.highwire.dtl.DTLVardef@4b997org.highwire.dtl.DTLVardef@349ee1_HPS_FORMAT_FIGEXP M_FIG C_FIG
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