Molecular genetic analysis of the evolution of cytotoxin-converting phages and the horizontal transfer of toxin genes.

CTX是一种细胞毒素转化相位分离的从Pseudomonas aeruginosa。在这项研究中，我们确定了φCTX相位基因组的完整核苷酸序列。精确基因组的大小为35，538个基点。47个ORFs在φCTX基因组上被识别，包括两个先前被识别的基因、ctx和int。在它们中，15个基因产品在粒子上被识别。φCTX基因组中最突出的特征是具有重叠P2和P2相关的相位的扩展同源性;超过ORFs的一半是标记为P2基因的同源性。对基因组的基因排列也高度依赖于两个相位，因此G+C内容和密码子的使用量最大，CTX基因与宿主P. aeruginosa染色体相似。在添加中，μ CTX找到了与P2共享的几个常见特征，包括形态学、非诱导性、LPS核心寡链肽作为受体和Cai-D22 + Cai-D2依赖受体绑定的使用。这些发现表明，CTX是一个P2-l ... More ike phage很好地适应了P. aeruginosa，并提供了细菌的间遗传分布和演变的明确证据。Furthermore，对φCTX、P2和其他P2相关基因组结构的比较分析揭示了外国DNA存在的若干热点，包括细胞毒素基因，已插入。它们似乎将深入地纳入各种基因的采集中，这些基因被细菌感染水平地转移：假单胞菌产生三种类型的细菌素; R型、F型和S型丙酮。S型肌肽是一种简单的类似胆碱素的蛋白质，当R型表达细菌的Contractile Tail结构时，F型表达细菌的非Contractile Tail。自从φCTX是R pyocin相关相位的成员，其中R pyocin在遗传上和血清学上都与R pyocin相关，并提出了相关的结果，其中R pyocin与P2 phage家族的相关性。因此，R2 pyocin基因的核苷酸序列，与F2 pyocin中的那些位于P. aeruginosa PAO 1染色体组下游的R2基因簇，并已被分析成顺序替代了pyocins和细菌期之间的关系。进一步，在确定R2 pyocin位置时，我们确定了应变PML 14中的核苷酸序列的相应区域，其中只有F2 pyocin。结果清楚地证明了R型pocin是由P2 phage家族中常见的ancestral Origin衍生出来的，而F型则来自λ phage家族。这一运动是由识别一个Lysis基因盒来支持的，类似于那些用于细菌的。R2和F2 pyocin基因集群的基因组织， However认为，这两种pocin都不是简单的deficient phages，但它们的phages有尾巴，因为它们被进化专门化为细菌。Less（低）

φCTX is a cytotoxin-converting phage isolated from Pseudomons aeruginosa. In this study, we determined the complete nucleotide sequence of φCTX phage genome. The precise genome size was 35,538 bp. Forty seven ORFs were identified on the φCTX genome, including two previously identified genes, ctx and int. Among them, fifteen gene products were identified in the phage particle. The most striking feature of the φCTX genome was an extensive homology with the coliphage P2 and P2-related phages; more than half of the ORFs had marked homology to P2 genes. The gene arrangement on the genome was also highly conserved for the two phages, though the G+C content and codon usage of most φCTX genes were similar to those of the host P. aeruginosa chromosome. In addition, φCTX was found to share several common features with P2, including the morphology, non-inducibility, use of LPS core oligosaccharide as receptor and CaィイD22+ィエD2-dependent receptor binding. These findings indicate that φCTX is a P2-l … More ike phage well adapted to P. aeruginosa, and provide a clear evidence of the intergeneric spread and evolution of bacteriophages. Furthermore, comparative analysis of genome structures of φCTX, P2 and other P2-relatives revealed the presence of several hot spots where foreign DNAs, including the cytotoxin gene, were inserted. They appear to be deeply concerned in the acquisition of various genes that are horizontally transferred by bacteriophage infection.Pseudomonas aeruginosa produces three types of bacteriocins; R-type, F-type, and S-type pyocins. The S-type pyocin is a simple colicin-like protein, whereas the R-type resembles a contractile tail structure of bacteriophage, and the F-type a non-contractile tail of bacteriophage. Since φCTX is a member of R pyocin-related phages which are genetically and serologically related to R pyocin, above-mentioned results suggested the relatedness of R pyocin to the P2 phage family. Thus, the nucleotide sequence of R2 pyocin genes, along with those for F2 pyocin which are located downstream of the R2 gene cluster on the chromosome of P. aeruginosa PAO1, was analyzed in order to elucidate the relationship between the pyocins and bacteriophages. Further, in order to specify the R2 pyocin locus, we determined the nucleotide sequence of the corresponding region of the strain PML14 which produced only F2 pyocin. The results clearly demonstrated that the R-type pyocin is derived from a common ancestral origin with the P2 phage family and the F-type from the λ phage family. This notion was supported by identification of a lysis gene cassette similar to those for bacteriophages. The gene organization of the R2 and F2 pyocin gene cluster, however, suggested that the both pyocins are not simple defective phages but are phage tails that have been evolutionarily specialized as bacteriocins. Less