Gain and loss of the gonococcal genetic island in Neisseria

描述(申请人提供)：淋球菌基因岛(GGI)是一个57kb的DNA区域，在80%的淋病奈瑟菌菌株的染色体中发现，最近在脑膜炎奈瑟菌中发现。GGI序列表明，它是从另一个细菌物种水平获得的。它的侧翼是一个23bp的重复序列，其中一个拷贝构成了淋球菌复制终点处的大部分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。在大肠杆菌中，已经证明dif和XerCD促进了染色体二聚体的分解，这些二聚体是由染色体复制后的同源重组产生的。脑膜炎奈瑟氏菌中GGI的鉴定表明，GGI可能在奈瑟氏菌种间水平转移。 这项建议描述了实验，以表征涉及获取和切除GGI的机制，以及与脑膜炎奈瑟菌菌株获得GGI相关的表型。淋病奈瑟氏菌GGI缺失的特征表明，dif序列有助于通过定点重组进行切除。从几个脑膜炎奈瑟菌分离株的GGI上有限的DNA序列信息确定了脑膜炎球菌分离株的IV型分泌系统基因，但某些假定的表面成分以不同的形式存在。这些数据表明，IV型分泌系统可能在脑膜炎奈瑟菌中发挥不同的功能，并可能受到免疫监测。这些研究将进一步表征脑膜炎奈瑟菌GGIs的基因含量，并检查它们对培养中人类细胞感染的影响。 这项建议描述了实验，以表征涉及获取和切除GGI的机制，以及与脑膜炎奈瑟菌菌株获得GGI相关的表型。这些研究将进一步表征脑膜炎奈瑟菌GGIs的基因含量，并检查它们对培养中人类细胞感染的影响。

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.