Human- and Plant-Pathogenic Pseudomonas Species Produce Bacteriocins Exhibiting Colicin M-Like Hydrolase Activity towards Peptidoglycan Precursors
Human- and Plant-Pathogenic Pseudomonas Species Produce Bacteriocins Exhibiting Colicin M-Like Hydrolase Activity towards Peptidoglycan Precursors
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DOI：
10.1128/jb.01824-08
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发表时间：
2009-06-01
影响因子：
3.2
通讯作者：
Mengin-Lecreulx, Dominique
中科院分区：
文献类型：
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作者：
Barreteau, Helene;Bouhss, Ahmed;Mengin-Lecreulx, Dominique
在铜绿假单胞菌（P. aeruginosa）、丁香假单胞菌（P. syringae）和荧光假单胞菌（P. fluorescens）等假单胞菌的基因组中发现了与大肠杆菌colicin M c末端结构域相似的蛋白编码基因。这些基因仅在有限数量的菌株中检测到。例如，在P. aeruginosa中，大肠杆菌素M同源基因位于含有exu的基因组岛A中，这是一个大的水平获得的遗传元件和毒力决定因素。本文报道了三种假单胞菌中这些基因的克隆以及不同大肠杆菌素M同源物的纯化和生化特性。结果表明，它们在体外对两种十一戊烯基磷酸连接肽聚糖前体（脂质I和II）均表现出Mg2+依赖性二磷酸二酯水解酶活性。在所有情况下，裂解位点都定位在这些前体的十一戊烯基和焦磷酸- murnac部分之间。这些酶对细胞质前体udp - murnac -五肽没有活性，或（或仅很差）对焦磷酸十一烯基没有活性。这些大肠杆菌素M同源物具有较窄范围的抗菌活性。低浓度的铜绿假单胞菌蛋白可以抑制敏感菌株的生长。因此，这些蛋白质代表了一类新的细菌素（pyocins），这是迄今为止在假单胞菌属中首次报道的靶向肽聚糖代谢的细菌素。
Genes encoding proteins that exhibit similarity to the C-terminal domain of Escherichia coli colicin M were identified in the genomes of some Pseudomonas species, namely, P. aeruginosa, P. syringae, and P. fluorescens. These genes were detected only in a restricted number of strains. In P. aeruginosa, for instance, the colicin M homologue gene was located within the ExoU-containing genomic island A, a large horizontally acquired genetic element and virulence determinant. Here we report the cloning of these genes from the three Pseudomonas species and the purification and biochemical characterization of the different colicin M homologues. All of them were shown to exhibit Mg2+-dependent diphosphoric diester hydrolase activity toward the two undecaprenyl phosphate-linked peptidoglycan precursors (lipids I and II) in vitro. In all cases, the site of cleavage was localized between the undecaprenyl and pyrophospho-MurNAc moieties of these precursors. These enzymes were not active on the cytoplasmic precursor UDP-MurNAc-pentapeptide or (or only very poorly) on undecaprenyl pyrophosphate. These colicin M homologues have a narrow range of antibacterial activity. The P. aeruginosa protein at low concentrations was shown to inhibit growth of sensitive P. aeruginosa strains. These proteins thus represent a new class of bacteriocins (pyocins), the first ones reported thus far in the genus Pseudomonas that target peptidoglycan metabolism.