A gonococcal porA pseudogene:: implications for understanding the evolution and pathogenicity of Neisseria gonorrhoeae
A gonococcal porA pseudogene:: implications for understanding the evolution and pathogenicity of Neisseria gonorrhoeae
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DOI：
10.1046/j.1365-2958.1998.01101.x
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发表时间：
1998-11-01
影响因子：
3.6
通讯作者：
Maiden, MCJ
中科院分区：
文献类型：
--
作者：
Feavers, IM;Maiden, MCJ
奈瑟氏菌属的成员，包括人类病原体脑膜炎奈瑟氏菌和淋病奈瑟氏菌，表达相关孔蛋白家族的至少一个成员，N.脑膜炎球菌是已知表达第二种孔蛋白的唯一物种，即脑膜炎球菌血清亚型抗原PorA，是该家族中最不同的成员。出乎意料的是，在淋球菌基因组中鉴定出porA基因。淋球菌和脑膜炎球菌的porA基因座相邻的大肠杆菌greA基因的同源物，虽然在一些脑膜炎球菌porA下游的IS1106元件是不存在的淋球菌。几乎相同的porA位点存在于四个无关的淋球菌菌株和淋病患者的临床标本。淋球菌中PorA表达的缺乏是由于启动子区的突变（这阻止了转录）和porA基因编码区的移码突变所致。杂交和扩增实验表明，在其他七种奈瑟菌属的porA基因的情况下，porA是由淋球菌和脑膜炎球菌的共同祖先获得的，但在淋球菌的物种形成中失活，这意味着，虽然在上呼吸道的定植过程中是有利的，但这种蛋白质在泌尿生殖道的定植中没有功能，或阻碍泌尿生殖道的定植。
Members of the genus Neisseria, including the human pathogens Neisseria meningitidis and Neisseria gonorrhoeae, express at least one member of a family of related porins, N. meningitidis is the only species known to express a second porin, the meningococcal serosubtyping antigen PorA, the most divergent member of this family. Unexpectedly, a porA gene was identified in the gonococcal genome. Both the gonococcal and meningococcal porA loci were adjacent to a homologue of the Escherichia coli greA gene, although the IS1106 element downstream of porA in some meningococci was absent in the gonococcus. Almost identical porA loci were present in four unrelated gonococcal isolates and clinical specimens from patients with gonorrhoea. Lack of PorA expression in the gonococcus resulted from mutations in the promoter region, which prevented transcription, and frameshift mutations in the coding region of the porA gene. Hybridization and amplification experiments, showing the absence of a porA gene in seven other Neisseria species, suggested that porA was acquired by a common ancestor of the gonococcus and meningococcus but inactivated in the gonococcus on speciation, This implies that, while advantageous during colonization of the upper respiratory tract, this protein has no function in, or hinders, colonization of the urogenital tract.