Chlamydia trachomatis Plasmid-Encoded Pgp4 Is a Transcriptional Regulator of Virulence-Associated Genes
Chlamydia trachomatis Plasmid-Encoded Pgp4 Is a Transcriptional Regulator of Virulence-Associated Genes
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DOI：
10.1128/iai.01305-12
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发表时间：
2013-03-01
影响因子：
3.1
通讯作者：
Caldwell, Harlan D.
中科院分区：
文献类型：
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作者：
Song, Lihua;Carlson, John H.;Caldwell, Harlan D.
沙眼衣原体引起眼睛和生殖道的慢性炎症性疾病，具有全球医学重要性。衣原体质粒在这些疾病的病理生理学中起着重要作用，因为质粒缺陷的生物体是高度减毒的。隐蔽质粒携带非编码RNA和8个保守的开放阅读框（ORF）。为了理解质粒基因功能，我们产生了在八个ORF中的每一个中具有缺失的质粒穿梭载体。使用单个缺失突变体转化衣原体，并在表型和转录水平上表征转化体。我们发现，pgp 1，-2，-6，和-8质粒的维护是必不可少的，而其他的ORF可以删除和质粒稳定地保持。我们进一步表明，pgp 4基因敲除突变体表现出类似于其同基因无质粒菌株的体外表型，在异常包涵体形态和缺乏糖原积累方面。微阵列和qRT-PCR分析表明，Pgp 4是质粒编码的pgp 3和多个染色体基因，包括糖原合成酶基因glgA，这可能是重要的衣原体毒力的转录调节因子。我们的发现对于在分子水平上理解质粒在衣原体致病中的作用具有重要意义。
Chlamydia trachomatis causes chronic inflammatory diseases of the eye and genital tract and has global medical importance. The chlamydial plasmid plays an important role in the pathophysiology of these diseases, as plasmid-deficient organisms are highly attenuated. The cryptic plasmid carries noncoding RNAs and eight conserved open reading frames (ORFs). To understand plasmid gene function, we generated plasmid shuttle vectors with deletions in each of the eight ORFs. The individual deletion mutants were used to transform chlamydiae and the transformants were characterized phenotypically and at the transcriptional level. We show that pgp1, -2, -6, and -8 are essential for plasmid maintenance, while the other ORFs can be deleted and the plasmid stably maintained. We further show that a pgp4 knockout mutant exhibits an in vitro phenotype similar to its isogenic plasmidless strain, in terms of abnormal inclusion morphology and lack of glycogen accumulation. Microarray and qRT-PCR analysis revealed that Pgp4 is a transcriptional regulator of plasmid-encoded pgp3 and multiple chromosomal genes, including the glycogen synthase gene glgA, that are likely important in chlamydial virulence. Our findings have major implications for understanding the plasmid's role in chlamydial pathogenesis at the molecular level.