Identification of a genomic island present in the majority of pathogenic isolates of Pseudomonas aeruginosa
Identification of a genomic island present in the majority of pathogenic isolates of Pseudomonas aeruginosa
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DOI：
10.1128/jb.183.3.843-853.2001
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发表时间：
2001-02-01
影响因子：
3.2
通讯作者：
Lory, S
中科院分区：
文献类型：
--
作者：
Liang, XY;Pham, XQT;Lory, S
铜绿假单胞菌（Pseudomonasaeruginosa）是一种普遍存在的革兰氏阴性细菌，能够在广泛的环境小生境中定殖，并且还能够在人类中引起严重的感染。为了了解致病性铜绿假单胞菌菌株的遗传组成，开发了克隆DNA片段的阵列文库的差异杂交方法。来自菌株X24509的DNA的M13文库，分离自泌尿道感染患者，使用来自铜绿假单胞菌菌株PAO 1的DNA探针进行筛选。PAO 1的基因组最近已被测序，可用作比较不同菌株的遗传组织的参考。不与来自PAO 1的DNA探针反应的M13克隆携带X24509特异性插入物。当使用来自不同菌株的DNA探针进行类似的阵列杂交分析时，鉴定了一组M13克隆，其携带存在于来自广泛临床来源的大多数人铜绿假单胞菌分离物中的序列，这些克隆的插入片段用于鉴定包含X24509染色体上称为PAGI-1的连续48.9-kb区域的互补序列（用于“铜绿假单胞菌基因组岛1”）。PAGI-1被整合到X24509染色体的一个基因座上，该基因座显示出菌株PAO 1中存在的6，729-bp区域的缺失。对PAGI-1的发生率的调查显示，该岛存在于85%的临床来源的菌株中，大约一半的携带PAGI-1的菌株显示与X24509相同的缺失，而其余的菌株既含有PAGI-1序列又含有6，729-bp的PAO 1片段。这些基因中的几个编码的产品具有可预测的功能的基础上，其序列相似性的已知基因，包括插入序列，调节蛋白的决定簇，一些脱氢酶基因同源物，和两个蛋白质的参与解毒的活性氧。PAGI-1很可能是由大量铜绿假单胞菌分离株通过水平基因转移获得的。其维持的选择可能是任何一种功能未知的基因或允许铜绿假单胞菌在产生活性氧的条件下存活的基因表达的结果。或者，PAGI-1中编码的一种或两种转录调节因子可以控制铜绿假单胞菌染色体中基因的表达，这为获得该基因组岛的菌株提供了选择优势。
Pseudomonas aeruginosa, a ubiquitous gram-negative bacterium, is capable of colonizing a wide range of environmental niches and can also cause serious infections in humans, In order to understand the genetic makeup of pathogenic P. aeruginosa strains, a method of differential hybridization of arrayed libraries of cloned DNA fragments was developed, An M13 library of DNA from strain X24509, isolated from a patient with a urinary tract infection, was screened using a DNA probe from P. aeruginosa strain PAO1. The genome of PAO1 has been recently sequenced and can be used as a reference for comparisons of genetic organization in different strains. M13 clones that did not react with a DNA probe from PAO1 carried X24509-specific inserts. When a similar array hybridization analysis with DNA probes from different strains was used, a set of M13 clones which carried sequences present in the majority of human P. aeruginosa isolates from a wide range of clinical sources was identified, The inserts of these clones were used to identify cosmids encompassing a contiguous 48.9-kb region of the X24509 chromosome called PAGI-1 (for "P. aeruginosa genomic island 1"). PAGI-1 is incorporated in the X24509 chromosome at a locus that shows a deletion of a 6,729-bp region present in strain PAO1. Survey of the incidence of PAGI-1 revealed that this island is present in 85% of the strains from clinical sources, Approximately half of the PAGI-1-carrying strains show the same deletion as X24509, while the remaining strains contain both the PAGI-1 sequences and the 6,729-bp PAO1 segment, Sequence analysis of PAGI-1 revealed that it contains 51 predicted open reading frames. Several of these genes encoded products with predictable function based on their sequence similarities to known genes, including insertion sequences, determinants of regulatory proteins, a number of dehydrogenase gene homologs, and two for proteins of implicated in detoxification of reactive oxygen species. It is very likely that PAGI-1 was acquired by a large number of P. aeruginosa isolates through horizontal gene transfer. The selection for its maintenance may be the consequence of expression of any one of the genes of unknown function or the genes which allow P. aeruginosa to survive under the conditions that generate reactive oxygen species. Alternatively, one or both of the transcriptional regulators encoded in PAGI-1 may control the expression of genes in the P. aeruginosa chromosome, which provides a selective advantage for strains that have acquired this genomic island.