Strauch Eckhard, Goelz Greta, Knabner Dorothea, Konietzny Antje, Lanka Erich, Appel Bernd
Robert Koch-Institut, Projekt Horizontaler Gentransfer, Nordufer 20, D-13353 Berlin, Germany.
Max-Planck-Institut für Molekulare Genetik, Dahlem D-14195 Berlin, Germany.
Microbiology (Reading). 2003 Oct;149(Pt 10):2829-2845. doi: 10.1099/mic.0.26418-0.
Yersinia enterocolitica 29930 (biotype 1A; O : 7,8), the producing strain of the phage-tail-like bacteriocin enterocoliticin, possesses a plasmid-encoded conjugative type IV transfer system. The genes of the conjugative system were found by screening of a cosmid library constructed from total DNA of strain 29930. The cosmid Cos100 consists of the vector SuperCos1 and an insert DNA of 40 303 bp derived from a cryptic plasmid of strain 29930. The conjugative transfer system consists of genes encoding a DNA transfer and replication system (Dtr) with close relationship to the mob region of the mobilizable plasmid CloDF13 and a gene cluster encoding a mating pair formation system (Mpf) closely related to the Mpf system of the IncX plasmid R6K. However, a gene encoding a homologue of TaxB, the coupling protein of the IncX system, is missing. The whole transfer region has a size of approximately 17 kb. The recombinant plasmid Cos100 was shown to be transferable between Escherichia coli and Yersinia with transfer frequencies up to 0.1 transconjugants per donor. Mutations generated by inserting a tetracycline cassette into putative tri genes yielded a transfer-deficient phenotype. Conjugative transfer of the cryptic plasmid could not be demonstrated in the original host Y. enterocolitica 29930. However, a kanamycin-resistance-conferring derivative of the plasmid was successfully introduced into E. coli K-12 by transformation and was shown to be self-transmissible. Furthermore, Southern blot hybridization and PCR experiments were carried out to elucidate the distribution of the conjugative transfer system in Yersinia. In total, six Y. enterocolitica biotype 1A strains harbouring closely related systems on endogenous plasmids were identified.
小肠结肠炎耶尔森菌29930（生物型1A；O:7,8）是噬菌体尾样细菌素小肠结肠炎菌素的产生菌株，拥有一个质粒编码的接合型IV型转移系统。通过筛选由菌株29930的总DNA构建的黏粒文库，发现了接合系统的基因。黏粒Cos100由载体SuperCos1和一段40303 bp的插入DNA组成，该插入DNA来源于菌株29930的一个隐蔽质粒。接合转移系统由编码与可移动质粒CloDF13的mob区域密切相关的DNA转移和复制系统（Dtr）的基因以及编码与IncX质粒R6K的Mpf系统密切相关的配对形成系统（Mpf）的基因簇组成。然而，缺少一个编码IncX系统的偶联蛋白TaxB同源物的基因。整个转移区域大小约为17 kb。重组质粒Cos100在大肠杆菌和耶尔森菌之间可转移，转移频率高达每供体0.1个转接合子。通过将四环素盒插入假定的tri基因产生的突变产生了转移缺陷表型。在原始宿主小肠结肠炎耶尔森菌29930中未证明隐蔽质粒的接合转移。然而，该质粒的一个赋予卡那霉素抗性的衍生物通过转化成功导入大肠杆菌K-12，并显示具有自我转移性。此外，进行了Southern印迹杂交和PCR实验以阐明接合转移系统在耶尔森菌中的分布。总共鉴定出6株小肠结肠炎耶尔森菌生物型1A菌株，它们在内源质粒上携带密切相关的系统。
