Osorio Carlos R, Juiz-Río Sandra, Lemos Manuel L
Department of Microbiology and Parasitology, Institute of Aquaculture and Faculty of Biology, University of Santiago de Compostela, Santiago de Compostela 15782, Galicia, Spain.
Microbiology (Reading). 2006 Nov;152(Pt 11):3327-3341. doi: 10.1099/mic.0.29190-0.
Photobacterium damselae subsp. piscicida, the causative agent of fish pasteurellosis, produces a siderophore which is distinct from that produced by P. damselae subsp. damselae. Using suppression subtractive hybridization, a subsp. piscicida-specific DNA region of 35 kb was identified in strain DI21, and 11 genes were defined: dahP, araC1, araC2, frpA, irp8, irp2, irp1, irp3, irp4, irp9 and irp5. The sequence of the predicted proteins encoded by these genes showed significant similarity with the proteins responsible for the synthesis and transport of the siderophore yersiniabactin, encoded within the Yersinia high-pathogenicity island (HPI). Southern hybridization demonstrated that this gene cluster is exclusive to some European subsp. piscicida isolates. Database searches revealed that a similar gene cluster is present in Photobacterium profundum SS9 and Vibrio cholerae RC385. An irp1 gene (encoding a putative non-ribosomal peptide synthetase) insertional mutant (CS31) was impaired for growth under iron-limiting conditions and unable to produce siderophores, and showed an approximately 100-fold decrease in degree of virulence for fish. The subsp. piscicida DI21 strain, but not CS31, promoted the growth of a Yersinia enterocolitica irp1 mutant. Furthermore, a yersiniabactin-producing Y. enterocolitica strain as well as purified yersiniabactin were able to cross-feed strains DI21 and CS31, suggesting that the subsp. piscicida siderophore might be functionally and structurally related to yersiniabactin. The differential occurrence among P. damselae strains, and the low sequence similarity to siderophore synthesis genes described in other members of the Vibrionaceae, suggest that this genetic system might have been acquired by horizontal transfer in P. damselae subsp. piscicida, and might have a common evolutionary origin with the Yersinia HPI.
杀鲑气单胞菌嗜鱼亚种是鱼类巴斯德氏菌病的病原体，它产生一种与杀鲑气单胞菌美人鱼亚种所产生的铁载体不同的铁载体。利用抑制性消减杂交技术，在DI21菌株中鉴定出一个35 kb的嗜鱼亚种特异性DNA区域，并确定了11个基因：dahP、araC1、araC2、frpA、irp8、irp2、irp1、irp3、irp4、irp9和irp5。这些基因编码的预测蛋白质序列与耶尔森氏菌高致病性岛（HPI）内编码的负责耶尔森菌素铁载体合成和运输的蛋白质具有显著相似性。Southern杂交表明，该基因簇是一些欧洲嗜鱼亚种分离株所特有的。数据库搜索显示，在深海发光杆菌SS9和霍乱弧菌RC385中存在类似的基因簇。一个irp1基因（编码一种假定的非核糖体肽合成酶）插入突变体（CS31）在铁限制条件下生长受损，无法产生铁载体，并且对鱼类的毒力程度下降了约100倍。嗜鱼亚种DI21菌株而非CS31菌株促进了小肠结肠炎耶尔森氏菌irp1突变体的生长。此外，一株产生耶尔森菌素的小肠结肠炎耶尔森氏菌菌株以及纯化的耶尔森菌素能够交叉喂养DI21和CS31菌株，这表明嗜鱼亚种的铁载体在功能和结构上可能与耶尔森菌素相关。杀鲑气单胞菌菌株之间的差异出现情况，以及与弧菌科其他成员中描述的铁载体合成基因的低序列相似性，表明这个遗传系统可能是通过水平转移在杀鲑气单胞菌嗜鱼亚种中获得的，并且可能与耶尔森氏菌HPI有共同的进化起源。
