Gain and loss of the gonococcal genetic island in Neisseria

描述（由申请人提供）：淋球菌遗传岛（GGI）是一个57 kb的DNA区域，存在于80%的淋病奈瑟菌菌株的染色体中，最近在脑膜炎奈瑟菌中发现。GGI序列显示它是从另一种细菌物种水平获得的证据。它的侧翼是一个23 bp的重复序列，其中一个拷贝构成了淋球菌复制末端的大部分dif位点。重复序列的第二个拷贝是dif序列的不完整拷贝的一部分。dif是由位点特异性重组酶XerCD识别的序列。在大肠已经显示dif和XerCD促进染色体二聚体的拆分，所述染色体二聚体由染色体复制后的同源重组产生。对N.脑膜炎双球菌属表明GGI可能在奈瑟氏菌属种之间水平转移。 该建议描述了实验，以表征参与的收购和切除的GGI的机制和表型与收购的GGI由N。脑膜炎菌株。N.淋病表明DIF序列通过位点特异性重组促进切除。有限的DNA序列信息的GGI从几个N。脑膜炎球菌分离株鉴定出脑膜炎球菌分离株中的IV型分泌系统基因，但某些推定的表面组分以变体形式存在。这些数据表明，IV型分泌系统可能在N.脑膜炎，并可能受到免疫监视。这些研究将进一步表征N.脑膜炎球菌GGIs，并检查它们对培养的人细胞感染的影响。 该建议描述了实验，以表征参与的收购和切除的GGI的机制和表型与收购的GGI由N。脑膜炎菌株。这些研究将进一步表征N.脑膜炎球菌GGIs，并检查它们对培养的人细胞感染的影响。

DESCRIPTION (provided by applicant): The gonococcal genetic island (GGI) is a 57 kb region of DNA that is found in the chromosomes of 80% of Neisseria gonorrhoeae strains and was recently identified in Neisseria meningitidis. The GGI sequence shows evidence that it was horizontally acquired from another bacterial species. It is flanked by a 23-bp repeat, one copy of which makes up most of the dif site at the gonococcal replication terminus. The second copy of the repeat is part of an imperfect copy of the dif sequence. dif is a sequence that is recognized by the site-specific recombinase XerCD. In E. coli it has been shown that dif and XerCD facilitate the resolution of chromosomal dimers that result from homologous recombination following chromosomal replication. The identification of the GGI in N. meningitidis suggests that the GGI may be horizontally transferred between Neisseria species. This proposal describes experiments to characterize the mechanisms involved in acquisition and excision of the GGI and the phenotypes associated with acquisition of the GGI by N. meningitidis strains. Characterization of GGI loss in N. gonorrhoeae indicates that the dif sequence facilitates excision by site-specific recombination. Limited DNA sequence information on the GGI from several N. meningitidis isolates identifies type IV secretion system genes in the meningococcal isolates, but that certain putative surface components exist in variant forms. These data suggest that the type IV secretion system may function differently in N. meningitidis and may be subject to immune surveillance. These studies will further characterize the gene content of the N. meningitidis GGIs and examine their effects on infection of human cells in culture. This proposal describes experiments to characterize the mechanisms involved in acquisition and excision of the GGI and the phenotypes associated with acquisition of the GGI by N. meningitidis strains. These studies will further characterize the gene content of the N. meningitidis GGIs and examine their effects on infection of human cells in culture.