Eikenella corrodens phase variation involves a posttranslational event in pilus formation.
Eikenella corrodens phase variation involves a posttranslational event in pilus formation.
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Eikenella corrodens 相变涉及菌毛形成中的翻译后事件。
DOI：
10.1128/jb.181.14.4154-4160.1999
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发表时间：
1999
影响因子：
3.2
通讯作者：
Hirschberg,RL
中科院分区：
文献类型：
--
作者：
Villar,MT;Helber,JT;Hood,B;Schaefer,MR;Hirschberg,RL
人类病原体Eikenella corrodenssynthesizes IV型皮利，并表现出一个相位变化，涉及不可逆的转变，从piliated到nonpiliated变种。在固体培养基上，有纤毛的变体形成小的（S-相）、腐蚀性菌落，而无纤毛的变体形成大的（L-相）、非腐蚀性菌落。我们正在临床分离株中研究这种相位变化的分子基础。腐蚀VA 1.从菌株VA 1的S期变体中克隆了编码主要IV型菌毛蛋白的基因组片段。序列分析表明，该片段含有4个串联的潜在开放阅读框架（ORF），分别命名为pilA 1、pilA 2、pilB和hagA。pilA 1和pilA 2均为IV型菌毛蛋白。BimB预测的蛋白质与DichelobacternodosusFimB菌毛装配蛋白具有序列同一性。hagA预测的蛋白质类似于血凝素。将含有这4个ORF的区域命名为pilA基因座。DNA杂交和序列分析表明，VA 1株L期变异株的pilA位点与S期变异株的pilA位点完全相同。一个丰富的pilA 1转录起始pilA 1的上游和终止于pilA 1和pilA 2之间的一个预测的发夹结构被检测到的几个测定，是一个不太丰富的通读转录pilA 1，pilA 2，和pilB。从thepilA基因座的转录是几乎无法区分的S-和L-期的变体。电子显微镜和免疫化学分析表明，S期变异体合成，出口，并组装成皮利菌毛蛋白。相反，L-期变体合成菌毛蛋白，但不输出并组装成皮利。这些数据表明，翻译后事件，可能涉及改变菌毛蛋白出口和组装，是负责相位变化inE。腐蚀
The human pathogenEikenella corrodenssynthesizes type IV pili and exhibits a phase variation involving the irreversible transition from piliated to nonpiliated variants. On solid medium, piliated variants form small (S-phase), corroding colonies whereas nonpiliated variants form large (L-phase), noncorroding colonies. We are studying the molecular basis of this phase variation in the clinical isolateE. corrodensVA1. A genomic fragment encoding the major type IV pilin was cloned from the S-phase variant of strain VA1. Sequence analysis of the fragment revealed four tandemly arranged potential open reading frames (ORFs), designatedpilA1,pilA2,pilB, andhagA. BothpilA1andpilA2predict a type IV pilin. The protein predicted bypilBshares sequence identity with theDichelobacter nodosusFimB fimbrial assembly protein. The protein predicted byhagAresembles a hemagglutinin. The region containing these four ORFs was designated thepilAlocus. DNA hybridization and sequence analysis showed that thepilAlocus of an L-phase variant of strain VA1 was identical to that of the S-phase variant. An abundantpilA1transcript initiating upstream ofpilA1and terminating at a predicted hairpin structure betweenpilA1andpilA2was detected by several assays, as was a less abundant read-through transcript encompassingpilA1,pilA2, andpilB. Transcription from thepilAlocus was nearly indistinguishable between S- and L-phase variants. Electron microscopy and immunochemical analysis showed that S-phase variants synthesize, export, and assemble pilin into pili. In contrast, L-phase variants synthesize pilin but do not export and assemble it into pili. These data suggest that a posttranslational event, possibly involving an alteration in pilin export and assembly, is responsible for phase variation inE. corrodens.