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福氏 2a志贺菌 (Shigellaflexneriserotype 2a)是引起人类细菌性痢疾的主要病原体。本文在国际上首次完成了福氏 2a志贺菌 30 1株 (Sf30 1) (我国细菌性痢疾的优势流行株 )的全基因组核苷酸序列测定和初步分析。该基因组包括一条由 4 6 0 72 0 3个碱基对 (bp)组成的环状染色体和一个含 2 2 16 18bp的侵袭性大质粒pCP30 1以及另外两个小质粒。通过将Sf30 1的染色体序列与其亲源关系相近的非致病性大肠杆菌K - 12菌株MG16 5 5进行比较基因组学研究 ,发现Sf30 1的染色体上有 5 72Kb特异性序列 ,并形成了 32 0个长度大于 5 0bp的“痢疾岛” (Shigella island ,SIs) ,其中大于 1Kb的共计 131个。这些岛共包含 5 19个开放读码框架 (OpenReadingFrames,ORFs) ,多数SIs的一侧或两侧均伴有插入序列元件、转座子或者tRNAs。G +C含量及密码子使用频率等分析显示出部分SIs的外源性。通过结构及ORF编码产物功能的分析 ,鉴别出 9个可能与痢疾杆菌致病性有关的“毒力岛” ,其中 7个可能的毒力岛为首次发现
Shigella flexneri 2a is the major causative agent of human bacillary dysentery. In this paper, the first complete genome-wide nucleotide sequence determination and preliminary analysis of 30 F 2 Shigella spp. (Sf30 1) (the dominant epidemic strain of bacterial dysentery in China) were completed in the world. The genome consists of a circular chromosome consisting of 46,072 over a base pair (bp) and an invasive large plasmid pCP301 containing 2i1618bp and two other small plasmids. By comparing the chromosomal sequence of Sf301 with the nonpathogenic Escherichia coli K - 12 strain MG16 5 5, which has a close relative of its origin, we found 5 72 kb specific sequence on the chromosome of Sf30 1 and formed 32 0 A total of 131 Shigella islands (SIs) with a length of more than 50 bp, more than 1 Kb. These islands contain a total of 5 19 Open Reading Frames (ORFs), with insertion of sequence elements, transposons or tRNAs on one or both sides of most SIs. Analysis of G + C content and frequency of codon usage showed some exogenous SIs. Through the analysis of structure and function of ORF coding products, nine “virulent islands” that may be related to the pathogenicity of dysentery bacillus were identified. Among them, seven potential virulent islands were found for the first time