Lautru Sylvie, Deeth Robert J, Bailey Lianne M, Challis Gregory L
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
Nat Chem Biol. 2005 Oct;1(5):265-9. doi: 10.1038/nchembio731. Epub 2005 Sep 11.
Analyses of microbial genome sequences reveal numerous examples of gene clusters encoding proteins typically involved in complex natural product biosynthesis but not associated with the production of known natural products. In Streptomyces coelicolor M145 there are several gene clusters encoding new nonribosomal peptide synthetase (NRPS) systems not associated with known metabolites. Application of structure-based models for substrate recognition by NRPS adenylation domains predicts the amino acids incorporated into the putative peptide products of these systems, but the accuracy of these predictions is untested. Here we report the isolation and structure determination of the new tris-hydroxamate tetrapeptide iron chelator coelichelin from S. coelicolor using a genome mining approach guided by substrate predictions for the trimodular NRPS CchH, and we show that this enzyme, which lacks a C-terminal thioesterase domain, together with a homolog of enterobactin esterase (CchJ), are required for coelichelin biosynthesis. These results demonstrate that accurate prediction of adenylation domain substrate selectivity is possible and raise intriguing mechanistic questions regarding the assembly of a tetrapeptide by a trimodular NRPS.
对微生物基因组序列的分析揭示了众多基因簇的实例，这些基因簇编码的蛋白质通常参与复杂天然产物的生物合成，但与已知天然产物的产生无关。在天蓝色链霉菌M145中，有几个基因簇编码与已知代谢产物无关的新型非核糖体肽合成酶（NRPS）系统。基于结构的模型用于NRPS腺苷化结构域的底物识别，可预测这些系统假定肽产物中掺入的氨基酸，但这些预测的准确性尚未得到检验。在此，我们报告了使用基于底物预测的基因组挖掘方法，从天蓝色链霉菌中分离并确定了新的三异羟肟酸四肽铁螯合剂天蓝色菌素的结构，该方法以三模块NRPS CchH的底物预测为指导，并且我们表明这种缺乏C末端硫酯酶结构域的酶，与肠杆菌素酯酶的同源物（CchJ）一起，是天蓝色菌素生物合成所必需的。这些结果表明，腺苷化结构域底物选择性的准确预测是可能的，并提出了关于三模块NRPS组装四肽的有趣机制问题。
