加拿大拉瓦爾大學(xué)和丹麥丹尼斯克公司的一組研究人員揭開了細(xì)菌免疫系統(tǒng)的秘密，這一發(fā)現(xiàn)有可能解決某些細(xì)菌對(duì)抗生素產(chǎn)生抗藥性的難題,。該研究發(fā)表于11月4日的《自然》雜志上,。
由拉瓦爾大學(xué)生物化學(xué)、微生物學(xué)和生物信息學(xué)系西爾·莫埃努教授領(lǐng)導(dǎo)的研究小組發(fā)現(xiàn),，選擇特定的外源DNA（脫氧核糖核酸）片段并將其嵌入到細(xì)菌基因組的特定區(qū)域,，這些片段便可作為一種免疫因子，抵抗DNA裂解入侵,。這種技術(shù)又被稱為CRISPR/Cas技術(shù),。
研究人員利用質(zhì)粒——一種可與細(xì)菌進(jìn)行交換的DNA分子證明了這一機(jī)制。實(shí)驗(yàn)中,，研究人員將載有抗生素抗性基因的質(zhì)粒注入嗜熱鏈球菌中,。其中一些細(xì)菌將含有抗性基因的DNA片段整合到了其基因組中,。隨后的實(shí)驗(yàn)發(fā)現(xiàn)，這些細(xì)菌擁有了不再接受質(zhì)粒嵌入的特性,。莫埃努認(rèn)為,，這表明這些細(xì)菌獲得了對(duì)抗性基因的免疫能力。這種現(xiàn)象也可以解釋,，為什么一些細(xì)菌能夠發(fā)展出耐藥性,，而其他的細(xì)菌不具有耐藥性。
CRISPR/Cas免疫機(jī)制還可以防止噬菌體污染,。莫埃努認(rèn)為,，這一發(fā)現(xiàn)將對(duì)食品業(yè)、抗生素業(yè)及生物技術(shù)產(chǎn)業(yè)十分有益,，因?yàn)槭删w污染將大幅度增加這些行業(yè)的經(jīng)濟(jì)成本,。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature doi:10.1038/nature09523
The CRISPR/Cas bacterial immune system cleaves bacteriophage and plasmid DNA
Josiane E. Garneau,Marie-ève Dupuis,Manuela Villion,Dennis A. Romero,Rodolphe Barrangou,Patrick Boyaval,Christophe Fremaux,Philippe Horvath,Alfonso H. Magadán& Sylvain
Bacteria and Archaea have developed several defence strategies against foreign nucleic acids such as viral genomes and plasmids. Among them, clustered regularly interspaced short palindromic repeats (CRISPR) loci together with cas (CRISPR-associated) genes form the CRISPR/Cas immune system, which involves partially palindromic repeats separated by short stretches of DNA called spacers, acquired from extrachromosomal elements. It was recently demonstrated that these variable loci can incorporate spacers from infecting bacteriophages and then provide immunity against subsequent bacteriophage infections in a sequence-specific manner. Here we show that the Streptococcus thermophilus CRISPR1/Cas system can also naturally acquire spacers from a self-replicating plasmid containing an antibiotic-resistance gene, leading to plasmid loss. Acquired spacers that match antibiotic-resistance genes provide a novel means to naturally select bacteria that cannot uptake and disseminate such genes. We also provide in vivo evidence that the CRISPR1/Cas system specifically cleaves plasmid and bacteriophage double-stranded DNA within the proto-spacer, at specific sites. Our data show that the CRISPR/Cas immune system is remarkably adapted to cleave invading DNA rapidly and has the potential for exploitation to generate safer microbial strains.
