重复序列ERIC(IRU)研究进展

Research progress of ERIC(IRU)

重复序列几乎存在于所有生物的基因组中。"肠道细菌基因间重复序列"(Enterobacterial Repetitive Intergenic Consensus,ERIC)是主要存在于肠道细菌的一类基因间重复序列,也称为"基因间重复单位"(Intergenic Repetitive Unit,IRU)。ERIC(IRU)首先在大肠杆菌(Escherichia coli)中发现,后来又在多种其他细菌中发现。ERIC(IRU)长127bp,有的还有插入序列。绝大多数ERIC(IRU)都可以转录,mRNA形成茎环结构。ERIC(IRU)局限于基因组可转录区,即多顺反子操纵子基因间区域,或开放阅读框架上、下游非翻译区。ERIC(IRU)很可能调节侧翼基因(flanking gene)的表达。ERIC(IRU)高度保守,可能其变异受到自然选择压力的限制或它本身就可能是"自私的DNA"(selfish DNA)。Versalovic等建立起ERIC-PCR,它可以有效地同时平行分析不同生态系统的结构差异以及动态监测同一生态系统微生物群落结构的变化。近年来这一技术逐渐运用到对动物肠道菌群的研究上。

Repeat sequence exists in almost all organism genomes. Enterobacterial Repetitive Intergenic Consensus （ERIC）, also named Intergenic Repetitive Unit （IRU）, is a kind of intergenic repetitive sequence that exists predominantly in Enterobacteria. ERIC （IRU） was firstly discovered in Escherichia coli, followed by identification in many other bacteria. ERIC （IRU） is 127bp long, and some with inserted sequences. Most ERIC （IRU） can be transcribed, and mRNA forms a stem-loop structure. ERIC （IRU） is restricted to transcribed regions of the genome, either in intergenic regions of polycistronic operons or in untranslated regions upstream or downstream of open reading frames（ORF）. ERIC（IRU） probably modulates the expression of flanking genes. ERIC（IRU） is highly conserved, for either its variation is restricted by the natural selection pressure, or it＇s ＂selfish DNA＂. ERIC-PCR described by Versalovic et al. can efficiently analyze the variation of different ecological systems and monitor the development of microbial flora of the same ecological system. In recent years, this technology has been applied to study the microbial population of animal intestinal tract.