Molecular characterization of long direct repeat (LDR) sequences expressing a stable mRNA encoding for a 35-amino-acid cell-killing peptide and a cis-encoded small antisense RNA in Escherichia coli
Molecular characterization of long direct repeat (LDR) sequences expressing a stable mRNA encoding for a 35-amino-acid cell-killing peptide and a cis-encoded small antisense RNA in Escherichia coli
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DOI：
10.1046/j.1365-2958.2002.03042.x
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发表时间：
2002-07-01
影响因子：
3.6
通讯作者：
Mori, H
中科院分区：
文献类型：
--
作者：
Kawano, M;Oshima, T;Mori, H
对大肠杆菌K-12进行了基因组序列分析，发现了4个拷贝的长重复元件。这些序列被指定为长直接重复(LDR)序列。其中三个重复序列(LDR-A、-B、-C)，每个长约500bp，在遗传图谱上以串联重复的形式存在于27.4分钟。另一个拷贝(LDR-D)长450bp，与LDR-A、-B和-C几乎相同，位于79.7分钟，与LDR-A、-B和-C位置正好相反。在这项研究中，我们证明了LDR-D编码一个35个氨基酸的多肽LDRD，它的过度表达会导致宿主细胞的快速杀伤和核样凝聚。Northern杂交和引物延伸分析表明，编码LDRD的稳定的mRNA(约370个核苷酸)和不稳定的顺式编码的反义RNA(约60个核苷酸)组成转录，其功能是LDRD翻译的反式作用调节因子。我们建议LDR编码一个毒素-抗毒素模块。LDR-同源序列在任何已知的质粒上都不存在，但在沙门氏菌和其他肠道细菌物种中保守。
Genome sequence analyses of Escherichia coli K-12 revealed four copies of long repetitive elements. These sequences are designated as long direct repeat (LDR) sequences. Three of the repeats (LDR-A, -B, -C), each approximately 500 bp in length, are located as tandem repeats at 27.4 min on the genetic map. Another copy (LDR-D), 450 bp in length and nearly identical to LDR-A, -B and -C, is located at 79.7 min, a position that is directly opposite the position of LDR-A, -B and -C. In this study, we demonstrate that LDR-D encodes a 35-amino-acid peptide, LdrD, the overexpression of which causes rapid cell killing and nucleoid condensation of the host cell. Northern blot and primer extension analysis showed constitutive transcription of a stable mRNA (approximate to 370 nucleotides) encoding LdrD and an unstable cis -encoded antisense RNA (approximate to 60 nucleotides), which functions as a trans -acting regulator of ldrD translation. We propose that LDR encodes a toxin-antitoxin module. LDR-homologous sequences are not present on any known plasmids but are conserved in Salmonella and other enterobacterial species.