Kunzmann Martin H, Sieber Stephan A
Technische Universität München, Lichtenbergstrasse 4, Garching, Germany.
Mol Biosyst. 2012 Nov;8(11):3061-7. doi: 10.1039/c2mb25313e. Epub 2012 Sep 18.
α-Alkylidene-γ-butyrolactones are quite common in nature and exhibit a broad spectrum of biological activities. We therefore synthesized a small library of xanthatine inspired α-alkylidene-γ-butyrolactones to screen non-pathogenic and uropathogenic E. coli strains by activity based protein profiling (ABPP). The identified targets are involved in cellular redox processes and give first insight into the preferred binding sites of this privileged motif. Furthermore the gene of one protein, c2450, which was only identified in uropathogenic E. coli belongs to a genomic island which encodes a hybrid polyketide/non-ribosomal peptide synthetase (PKS/NRPS). This system is responsible for the synthesis of colibactin, a natural product which causes DNA double strand breaks in eukaryotic cells leading to the activation of the DNA damage checkpoint pathway and subsequent cell cycle arrest. While the role of several proteins that are involved in the colibactin synthesis has been elucidated, the function of c2450 remains elusive. Investigation of the binding site showed that c2450 is modified at a cysteine residue which may be important for the catalytic activity.
α-亚烷基-γ-丁内酯在自然界中相当常见，并具有广泛的生物活性。因此，我们合成了一个受黄嘌呤启发的α-亚烷基-γ-丁内酯小型文库，通过基于活性的蛋白质谱分析（ABPP）来筛选非致病性和致病性大肠杆菌菌株。鉴定出的靶点参与细胞氧化还原过程，并首次深入了解了这个特殊基序的优先结合位点。此外，一种仅在致病性大肠杆菌中鉴定出的蛋白质c2450的基因属于一个基因组岛，该基因组岛编码一种混合聚酮/非核糖体肽合成酶（PKS/NRPS）。这个系统负责合成大肠杆菌素，一种天然产物，它会导致真核细胞中的DNA双链断裂，从而激活DNA损伤检查点途径并导致随后的细胞周期停滞。虽然参与大肠杆菌素合成的几种蛋白质的作用已经阐明，但c2450的功能仍然不清楚。对其结合位点的研究表明，c2450在一个半胱氨酸残基处被修饰，这可能对催化活性很重要。
