Biosynthesis of the yellow xanthomonadin pigments involves an ATP-dependent 3-hydroxybenzoic acid: acyl carrier protein ligase and an unusual type II polyketide synthase pathway
Biosynthesis of the yellow xanthomonadin pigments involves an ATP-dependent 3-hydroxybenzoic acid: acyl carrier protein ligase and an unusual type II polyketide synthase pathway
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DOI：
10.1111/mmi.14064
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发表时间：
2018-10-01
影响因子：
3.6
通讯作者：
He, Ya-Wen
中科院分区：
文献类型：
--
作者：
Cao, Xue-Qiang;Wang, Jia-Yuan;He, Ya-Wen
黄单胞菌毒素是由植物病原体野油菜黄单胞菌致病变种（Xanthomonascampestris pv.）campestris（Xcc）.猪群负责黄单胞菌素的生物合成。以前，Xcc 4014的集群被表征为双功能分支酶，产生3-羟基苯甲酸（3-HBA）和4-HBA。在这项研究中，遗传分析确定了猪簇中对黄单胞菌素生物合成至关重要的11个基因。生化和生物信息学分析表明，黄单胞菌素是通过一个不寻常的II型聚酮合成酶途径合成的。猪簇在不产生黄单胞菌素的铜绿假单胞菌菌株中的异源表达导致了氯化黄单胞菌素样色素的合成。进一步分析表明，xanC编码酰基载体蛋白（ACP），而xanA 2编码ATP依赖性3-HBA：ACP连接酶。它们共同催化3-HBA形成3-HBA-S-ACP，启动黄单胞菌素的生物合成。最后，我们发现xanH编码一种FabG样酶，而xanK编码一种新型糖基转移酶。xanH和xanK不仅是黄单胞菌素生物合成所必需的，而且也是胞外多糖和DSF家族群体感应信号的平衡生物合成所必需的。这些研究结果为我们提供了一个更好的了解黄单胞菌素的生物合成机制，并直接证明存在广泛的串扰之间的黄单胞菌素的生物合成途径和其他代谢途径。
Xanthomonadins are yellow pigments that are produced by the phytopathogen Xanthomonas campestris pv. campestris (Xcc). A pig cluster is responsible for xanthomonadin biosynthesis. Previously, Xcc4014 of the cluster was characterized as a bifunctional chorismatase that produces 3-hydroxybenzoic acid (3-HBA) and 4-HBA. In this study, genetic analysis identified 11 genes within the pig cluster to be essential for xanthomonadin biosynthesis. Biochemical and bioinformatics analysis suggest that xanthomonadins are synthesized via an unusual type II polyketide synthase pathway. Heterologous expression of the pig cluster in non-xanthomonadin-producing Pseudomonasaeruginosa strain resulted in the synthesis of chlorinated xanthomonadin-like pigments. Further analysis showed that xanC encodes an acyl carrier protein (ACP) while xanA2 encodes a ATP-dependent 3-HBA:ACP ligase. Both of them act together to catalyse the formation of 3-HBA-S-ACP from 3-HBA to initiate xanthomonadin biosynthesis. Finally, we showed that xanH encodes a FabG-like enzyme and xanK encodes a novel glycosyltransferase. Both xanH and xanK are not only required for xanthomonadin biosynthesis, but also required for the balanced biosynthesis of extracellular polysaccharides and DSF-family quorum sensing signals. These findings provide us with a better understanding of xanthomonadin biosynthetic mechanisms and directly demonstrate the presence of extensive cross-talk among xanthomonadin biosynthetic pathways and other metabolic pathways.