Functional Divergence of FimX in PilZ Binding and Type IV Pilus Regulation
Functional Divergence of FimX in PilZ Binding and Type IV Pilus Regulation
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DOI：
10.1128/jb.00767-12
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发表时间：
2012-08
影响因子：
3.2
通讯作者：
Yaning Qi;Linghui Xu;Xueming Dong;Y. Yau;Chun Loong Ho;Siew Lee Koh;S. Shochat;S. Chou;K. Tang;Zhao-Xun Liang
中科院分区：
文献类型：
--
作者：
Yaning Qi;Linghui Xu;Xueming Dong;Y. Yau;Chun Loong Ho;Siew Lee Koh;S. Shochat;S. Chou;K. Tang;Zhao-Xun Liang
IV型菌毛（T4P）是一种极性表面结构，在细菌运动、生物膜形成和致病性中起重要作用。已知蛋白FimX及其同源物在人类病原体铜绿假单胞菌和其他一些细菌物种中介导T4P的形成。最近有报道称，从轴足黄单胞菌（Xanthomonas axonopodis pv.）中分离得到FimXXAC2398。citri通过FimXXAC2398的非酶EAL结构域直接与PilZXAC1133相互作用。在这里，我们提供的实验数据表明，FimXXAC2398和PilZXAC1133之间的强相互作用在P. aeruginosa和其他假单胞菌中并不保守。体外和体内结合实验表明，在铜绿假单胞菌中，FimX与PilZ的相互作用低于可测极限。表面等离子体共振实验进一步证实，铜绿假单胞菌蛋白之间的相互作用至少比轴足假单胞菌之间的相互作用弱3个数量级。citri一对。通过酰胺氢-氘交换和定点诱变研究，FimXXAC2398的n端叶状区被确定为PilZXAC1133的结合表面。在P. aeruginosa中，FimX的EAL结构域n端叶区缺少几个关键残基可能是导致FimX与PilZ结合亲和力大大降低的原因。综上所述，结果表明黄单胞菌物种中PilZ和FimX的相互作用在铜绿假单胞菌中并不保守，这是由于FimX同源基因在进化上存在差异。fixx和PilZ在细菌运动和T4P生物发生中的确切作用可能因细菌种类而异。
ABSTRACT Type IV pili (T4P) are polar surface structures that play important roles in bacterial motility, biofilm formation, and pathogenicity. The protein FimX and its orthologs are known to mediate T4P formation in the human pathogen Pseudomonas aeruginosa and some other bacterial species. It was reported recently that FimXXAC2398 from Xanthomonas axonopodis pv. citri interacts with PilZXAC1133 directly through the nonenzymatic EAL domain of FimXXAC2398. Here we present experimental data to reveal that the strong interaction between FimXXAC2398 and PilZXAC1133 is not conserved in P. aeruginosa and likely other Pseudomonas species. In vitro and in vivo binding experiments showed that the interaction between FimX and PilZ in P. aeruginosa is below the measurable limit. Surface plasmon resonance assays further confirmed that the interaction between the P. aeruginosa proteins is at least more than 3 orders of magnitude weaker than that between the X. axonopodis pv. citri pair. The N-terminal lobe region of FimXXAC2398 was identified as the binding surface for PilZXAC1133 by amide hydrogen-deuterium exchange and site-directed mutagenesis studies. Lack of several key residues in the N-terminal lobe region of the EAL domain of FimX is likely to account for the greatly reduced binding affinity between FimX and PilZ in P. aeruginosa. All together, the results suggest that the interaction between PilZ and FimX in Xanthomonas species is not conserved in P. aeruginosa due to the evolutionary divergence among the FimX orthologs. The precise roles of FimX and PilZ in bacterial motility and T4P biogenesis are likely to vary among bacterial species.