REARRANGEMENTS IN THE GENOME OF THE BACTERIUM SALMONELLA-TYPHI
REARRANGEMENTS IN THE GENOME OF THE BACTERIUM SALMONELLA-TYPHI
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DOI：
10.1073/pnas.92.4.1018
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发表时间：
1995-02-14
影响因子：
11.1
通讯作者：
SANDERSON, KE
中科院分区：
文献类型：
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作者：
LIU, SL;SANDERSON, KE
用脉冲场凝胶电泳法测定了伤寒病原菌伤寒沙门氏菌TY2的基因组图谱。用Xba I、Bin I和CEU I酶切TY2基因组，分别产生33、26和7个片段，分别排列在4780kb的环形染色体上。将转座子Tn10插入到鼠伤寒沙门氏菌的特异基因中，并将其导入伤寒沙门氏菌，通过Tn10的Xba I和Bin I位点定位37个伤寒沙门氏菌基因的位置。大肠杆菌K-12和鼠伤寒沙门氏菌LT2在染色体上的基因序列非常保守，而伤寒沙门氏菌TY2的基因序列不同，表明其在进化过程中经历了重大的基因组重排。这些重排包括rRNA的7个RRN操纵子之间的7个DNA片段的倒置和换位(推测是由于这些RRN基因中的同源重组)，覆盖复制终止区的另一个倒置(类似于在其他肠道细菌中发现的倒置)，以及至少3个插入，其中一个长达118kb。用只切割Rm基因的内含子编码的内切酶I-CEU I对基因组DNA进行部分酶切后，显示出明显由于Rm基因同源重组而导致的染色体重排，在所有测试的野生型伤寒沙门氏菌中都能检测到这种重排。这些重排可能被选择来补偿插入，否则会改变基因相对于复制起点和终点的位置。这些观察结果与我们对细菌基因组进化的看法有关，并可能对伤寒沙门氏菌的毒力具有重要意义。
We have determined the genomic map of the bacterium Salmonella typhi Ty2, the causal organism of typhoid fever, by using pulsed-field gel electrophoresis. Digestion of the Ty2 genome with endonucleases Xba I, Bin I, and Ceu I yielded 33, 26, and 7 fragments, respectively, that were placed in order on a circular chromosome of 4780 kb. Transposon Tn10 was inserted in specific genes of Salmonella typhimurium and transduced into S. typhi, and thus, the positions of 37 S. typhi genes were located through the Xba I and Bin I sites of the Tn10. Gene order on chromosomes of Escherichia coli K-12 and S. typhimurium LT2 is remarkably conserved; however, the gene order in S. typhi Ty2 is different, suggesting it has undergone major genomic rearrangements during its evolution. These rearrangements include inversions and transpositions in the 7 DNA fragments between the seven rrn operons for rRNA (postulated to be due to homologous recombination in these rrn genes), another inversion that covers the replication terminus region (resembling inversions found in other enteric bacteria), and at least three insertions, one as large as 118 kb. Partial digestion of genomic DNA with the intron-encoded endonuclease I-Ceu I, which cuts only in rm genes, shows chromosomal rearrangements, apparently due to homologous recombination in the rm genes, that were detected in all wild-type strains of S. typhi tested. These rearrangements may have been selected to compensate for the insertions that otherwise would have altered the locations of genes with respect to the origin and terminus of replication. These observations are relevant to our view of the evolution of the bacterial genome and may be significant in the virulence of S. typhi.