近日,，刊登在國(guó)際著名雜志PLoS Pathogens上的一篇研究報(bào)告“Genome-Wide Identification of Pseudomonas aeruginosa Virulence-Related Genes Using a Caenorhabditis elegans Infection Model”揭示了美國(guó)哈佛醫(yī)學(xué)院研究者的最新研究結(jié)果，在報(bào)告中,，研究者用秀麗線(xiàn)蟲(chóng)感染模型,，然后在全基因組的水平上揭示了和銅綠假單胞菌相關(guān)的毒性基因。
銅綠假單胞菌，又名綠膿桿菌,，是一種革蘭氏陰性機(jī)會(huì)致病菌,，也是醫(yī)院常見(jiàn)的獲得性感染菌株，可以引發(fā)患者急慢性的感染,，嚴(yán)重者可引發(fā)肺炎肺囊腫甚至肺癌,。
文章中，研究者用菌株P(guān)A14進(jìn)行實(shí)驗(yàn)研究,，他們用該菌株感染秀麗線(xiàn)蟲(chóng)（C.elegans）,，隨后運(yùn)用含有5850個(gè)單克隆的非冗余轉(zhuǎn)座突變體文庫(kù)來(lái)進(jìn)行篩選在C.elegans感染過(guò)程中細(xì)菌所涉及到的毒力基因。使用的突變體文庫(kù)可以覆蓋綠膿桿菌將近80%的基因組范圍,。
通過(guò)實(shí)驗(yàn),，研究者們發(fā)現(xiàn)了180個(gè)不同的突變體菌株（轉(zhuǎn)座子插入到了不同的毒力基因上），也就表明研究者發(fā)現(xiàn)了180個(gè)不同的毒力基因,，這其中包括已知的和新型的毒力基因,。7個(gè)以前其它功能的基因PchH、PchI,、PepP,、ClpA、PA0456,、PA0745和PA14_27700發(fā)現(xiàn)均和細(xì)菌毒力相關(guān),。后期研究者檢測(cè)了這些獨(dú)立基因在細(xì)菌中的正常表達(dá)水平，并且構(gòu)建了其系統(tǒng)分布圖譜,。
研究者揭示了,，主要作用于C.elegans的毒性基因既不是綠膿桿菌基因組的特異性區(qū)域，也不是假設(shè)的轉(zhuǎn)移基因組島,，或許是其它原核生物的共同的古老基因,。（生物谷Bioon.com）
doi:10.1371/journal.ppat.1002813
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Genome-Wide Identification of Pseudomonas aeruginosa Virulence-Related Genes Using a Caenorhabditis elegans Infection Model
Rhonda L. Feinbaum1, Jonathan M. Urbach1, Nicole T. Liberati1, Slavica Djonovic1, Allison Adonizio1, Anne-Ruxandra Carvunis2, Frederick M. Ausubel1*
Pseudomonas aeruginosa strain PA14 is an opportunistic human pathogen capable of infecting a wide range of organisms including the nematode Caenorhabditis elegans. We used a non-redundant transposon mutant library consisting of 5,850 clones corresponding to 75% of the total and approximately 80% of the non-essential PA14 ORFs to carry out a genome-wide screen for attenuation of PA14 virulence in C. elegans. We defined a functionally diverse 180 mutant set (representing 170 unique genes) necessary for normal levels of virulence that included both known and novel virulence factors. Seven previously uncharacterized virulence genes (ABC transporters PchH and PchI, aminopeptidase PepP, ATPase/molecular chaperone ClpA, cold shock domain protein PA0456, putative enoyl-CoA hydratase/isomerase PA0745, and putative transcriptional regulator PA14_27700) were characterized with respect to pigment production and motility and all but one of these mutants exhibited pleiotropic defects in addition to their avirulent phenotype. We examined the collection of genes required for normal levels of PA14 virulence with respect to occurrence in P. aeruginosa strain-specific genomic regions, location on putative and known genomic islands, and phylogenetic distribution across prokaryotes. Genes predominantly contributing to virulence in C. elegans showed neither a bias for strain-specific regions of the P. aeruginosa genome nor for putatively horizontally transferred genomic islands. Instead, within the collection of virulence-related PA14 genes, there was an overrepresentation of genes with a broad phylogenetic distribution that also occur with high frequency in many prokaryotic clades, suggesting that in aggregate the genes required for PA14 virulence in C. elegans are biased towards evolutionarily conserved genes.
