Genome sequences of Chlamydia trachomatis MoPn and Chlamydia pneumoniae AR39
Genome sequences of Chlamydia trachomatis MoPn and Chlamydia pneumoniae AR39
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DOI：
10.1093/nar/28.6.1397
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发表时间：
2000-03-15
影响因子：
14.9
通讯作者：
Fraser, CM
中科院分区：
文献类型：
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作者：
Read, TD;Brunham, RC;Fraser, CM
采用随机散弹法测定小鼠沙眼衣原体肺炎（MoPn）菌株Nigg （1 069 412 nt）和肺炎衣原体AR39 （1 229 853 nt）的基因组序列。MoPn基因组与先前测序的血清型沙眼衣原体基因序列和内容普遍保持一致，不同沙眼衣原体菌株之间的差异主要集中在终止起源附近的一个类似50 kb的“可塑性区”。在这一区域，MoPn含有一个新基因的3个拷贝，该基因编码一种bbbb3000个氨基酸的毒素，与大肠杆菌O157:H7中的一种预测毒素同源，但在这一区域明显失去了血清型D中发现的色氨酸生物合成基因。肺炎原体AR39染色体与先前测序的肺炎原体CWL029基因组的同源性为99.9%，但对比分析发现，在两个基因组中，尿嘧啶激酶基因上游有一个可逆的DNA片段，其方向不同。AR39还含有一种新的4524nt环状单链（ss）DNA噬菌体，这是首次报道感染肺炎原体的病毒。尽管衣原体基因组高度保守，但在关键的核苷酸挽救途径上存在有趣的差异：肺炎衣原体有一个用于dUTP产生的尿嘧啶激酶基因，MoPn有一个尿嘧啶磷酸核糖基转移酶，而血清沙眼衣原体D不含任何基因。染色体比较发现，沙眼衣原体和肺炎衣原体自物种分化以来发生了多次较大的反转事件，明显围绕复制起始轴和终止区进行。衣原体基因组的惊人一致性和串联复制基因的普遍存在是染色体重排和外源基因摄取最少的证据，可能是由于细胞内寄生物的生态隔离。在缺乏遗传分析的情况下，比较基因组学将继续为这些重要的人类病原体的毒力机制提供见解。
The genome sequences of Chlamydia trachomatis mouse pneumonitis (MoPn) strain Nigg (1 069 412 nt) and Chlamydia pneumoniae strain AR39 (1 229 853 nt) were determined using a random shotgun strategy. The MoPn genome exhibited a general conservation of gene order and content with the previously sequenced C.trachomatis serovar D. Differences between C.trachomatis strains were focused on an similar to 50 kb 'plasticity zone' near the termination origins. In this region MoPn contained three copies of a novel gene encoding a >3000 amino acid toxin homologous to a predicted toxin from Escherichia coli O157:H7 but had apparently lost the tryptophan biosyntheis genes found in serovar D in this region. The C.pneumoniae AR39 chromosome was >99.9% identical to the previously sequenced C.pneumoniae CWL029 genome, however, comparative analysis identified an invertible DNA segment upstream of the uridine kinase gene which was in different orientations in the two genomes. AR39 also contained a novel 4524 nt circular single-stranded (ss)DNA bacteriophage, the first time a virus has been reported infecting C.pneumoniae. Although the chlamydial genomes were highly conserved, there were intriguing differences in key nucleotide salvage pathways: C.pneumoniae has a uridine kinase gene for dUTP production, MoPn has a uracil phosphororibosyl transferase, while C.trachomatis serovar D contains neither gene. Chromosomal comparison revealed that there had been multiple large inversion events since the species divergence of C.trachomatis and C.pneumoniae, apparently oriented around the axis of the origin of replication and the termination region. The striking synteny of the Chlamydia genomes and prevalence of tandemly duplicated genes are evidence of minimal chromosome rearrangement and foreign gene uptake, presumably owing to the ecological isolation of the obligate intracellular parasites. In the absence of genetic analysis, comparative genomics will continue to provide insight into the virulence mechanisms of these important human pathogens.