Role of the Eikenella corrodens pilA locus in pilus function and phase variation.
Role of the Eikenella corrodens pilA locus in pilus function and phase variation.
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Eikenella corrodens pilA 基因座在菌毛功能和相位变化中的作用。
DOI：
10.1128/jb.183.1.55-62.2001
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发表时间：
2001
影响因子：
3.2
通讯作者：
Schaefer,MR
中科院分区：
文献类型：
--
作者：
Villar,MT;Hirschberg,RL;Schaefer,MR
人类病原体艾肯氏菌腐蚀表达IV型毛，并表现出从有毛到无毛的不可逆转变的阶段变化。在固体介质中，有毛变异形成小的（s相），腐蚀菌落，而非有毛变异形成大的（l相），不腐蚀菌落。我们正在研究临床分离性鼻炎患者鼻毛的结构和功能。corrodensVA1。早期的研究定义了包括pila1、pilA2、pilB和haga在内的pilalocus。pila1和pila2预测IV型菌毛蛋白，而pilb预测假定的菌毛组装蛋白。haga的作用尚未得到明确确立。这项工作还证实了pila1编码该菌株的主要毛蛋白，并表明阶段变化涉及毛形成的翻译后事件。在这项研究中，利用最近开发的s期变异VA1-S1的靶向介子诱变方案，研究了包含毛位点的单个基因的功能。不同的突变体与s期和l期突变体进行了相变化和IV型菌毛的生物合成和功能的几个不同方面的比较。s期细胞具有表面毛、自然转化能力和抽搐运动性，而l期细胞缺乏这些特征。失活的PilA1产生的突变体在表型上与l期突变体没有区别，这表明菌株VA1中IV型菌毛的天然生物合成依赖于PilA1的表达以及PilA1的适当输出和组装。失活的pila2产生的突变体在表型上与s期突变体难以区分，这表明pila2对于功能正常的毛的生物合成不是必需的。失活的PilB突变体缺乏抽搐运动，这表明PilB在这种与菌毛相关的现象中起作用。haga可能编码抗碲酸盐蛋白，其失活对菌毛的结构和功能没有影响。
The human pathogenEikenella corrodensexpresses 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 pilus structure and function in the clinical isolateE. corrodensVA1. Earlier work defined thepilAlocus which includespilA1,pilA2,pilB, andhagA. BothpilA1andpilA2predict a type IV pilin, whereaspilBpredicts a putative pilus assembly protein. The role ofhagAhas not been clearly established. That work also confirmed thatpilA1encodes the major pilus protein in this strain and showed that the phase variation involves a posttranslational event in pilus formation. In this study, the function of the individual genes comprising thepilAlocus was examined using a recently developed protocol for targeted interposon mutagenesis of S-phase variant VA1-S1. DifferentpilAmutants were compared to S-phase and L-phase variants for several distinct aspects of phase variation and type IV pilus biosynthesis and function. S-phase cells were characterized by surface pili, competence for natural transformation, and twitching motility, whereas L-phase cells lacked these features. Inactivation ofpilA1yielded a mutant that was phenotypically indistinguishable from L-phase variants, showing that native biosynthesis of the type IV pilus in strain VA1 is dependent on expression ofpilA1and proper export and assembly of PilA1. Inactivation ofpilA2yielded a mutant that was phenotypically indistinguishable from S-phase variants, indicating thatpilA2is not essential for biosynthesis of functionally normal pili. A mutant inactivated forpilBwas deficient for twitching motility, suggesting a role for PilB in this pilus-related phenomenon. Inactivation ofhagA, which may encode a tellurite resistance protein, had no effect on pilus structure or function.