Portnoy D A, Falkow S
J Bacteriol. 1981 Dec;148(3):877-83. doi: 10.1128/jb.148.3.877-883.1981.
A 44-megadalton plasmid associated with virulence and Ca2+ dependence from Yersinia enterocolitica 8081 was compared at the molecular level with a 47-megadalton plasmid associated with Ca2+ dependence from Yersinia pestis EV76. The plasmids were found to share 55% deoxyribonucleic acid sequence homology distributed over approximately 80% of the plasmid genomes. One region in which the plasmids differed was found to contain sequences concerned with essential plasmid functions. Forty-five mutants of Y. pestis were isolated which had spontaneously acquired the ability to grow on calcium-free medium (Ca2+ independence). Of these mutants, 21 were cured of their 47-megadalton plasmid, whereas the remaining had either suffered a major deletion of the plasmid or had a 2.2-kilobase insertion located in one of two adjacent BamHI restriction fragments encompassing approximately 9 kilobases. The inserted sequence was found at numerous sites on the Y. pestis chromosome and on all three plasmids in the strain and may represent a Y. pestis insertion sequence element.
将来自小肠结肠炎耶尔森菌8081的、与毒力和钙离子依赖性相关的44兆道尔顿质粒，在分子水平上与来自鼠疫耶尔森菌EV76的、与钙离子依赖性相关的47兆道尔顿质粒进行了比较。发现这两种质粒具有55%的脱氧核糖核酸序列同源性，分布在大约80%的质粒基因组上。发现这两种质粒不同的一个区域含有与质粒基本功能有关的序列。分离出45个鼠疫耶尔森菌突变体，它们自发获得了在无钙培养基上生长的能力（钙离子非依赖性）。在这些突变体中，21个失去了其47兆道尔顿的质粒，而其余的要么发生了质粒的大片段缺失，要么在包含大约9千碱基对的两个相邻BamHI限制片段之一中发生了2.2千碱基对的插入。发现该插入序列存在于鼠疫耶尔森菌染色体的多个位点以及该菌株的所有三个质粒上，可能代表一种鼠疫耶尔森菌插入序列元件。
