Graham M R, Lo R Y
Department of Microbiology, University of Guelph, Ontario, Canada.
Gene. 1997 Feb 28;186(2):201-5. doi: 10.1016/s0378-1119(96)00703-2.
A recombinant plasmid (pMG1) carrying Pasteurella haemolytica A1 DNA which complements a tonB mutation of Escherichia coli has been isolated. E. coli tonB metE which carries pMG1 exhibits growth kinetics in the presence of vitamin B12 similar to that of the wild-type host. In addition, the complemented E. coli is susceptible to killing by bacteriophage phi 80 and colicin B. Analysis of the nucleotide sequence in the complementing DNA showed that it codes for three genes in the order of exbB-exbD-tonB. This genetic organization has been reported in Haemophilus influenzae, H. ducreyi, Pseudomonas putida and Vibrio cholerae, and may represent a separate lineage of evolution from that of the Enterobacteriaceae in which tonB is unlinked with the accessory genes exbB and exbD. A comparison of the DNA flanking the exbB-exbD-tonB locus in P. haemolytica A1 and H. influenzae showed that the flanking regions are completely different between the two organisms.
已分离出一种携带溶血巴斯德菌A1 DNA的重组质粒（pMG1），该DNA可互补大肠杆菌的tonB突变。携带pMG1的大肠杆菌tonB metE在维生素B12存在下表现出与野生型宿主相似的生长动力学。此外，互补后的大肠杆菌易被噬菌体φ80和大肠杆菌素B杀死。对互补DNA的核苷酸序列分析表明，它按exbB-exbD-tonB的顺序编码三个基因。这种基因组织已在流感嗜血杆菌、杜氏嗜血杆菌、恶臭假单胞菌和霍乱弧菌中报道过，可能代表了与肠杆菌科不同的进化谱系，在肠杆菌科中tonB与辅助基因exbB和exbD不连锁。对溶血巴斯德菌A1和流感嗜血杆菌中exbB-exbD-tonB基因座两侧DNA的比较表明，这两种生物的侧翼区域完全不同。
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