Structural insights into the regulatory mechanism of the Pseudomonas aeruginosa YfiBNR system.
Structural insights into the regulatory mechanism of the Pseudomonas aeruginosa YfiBNR system.
复制标题
铜绿假单胞菌 YfiBNR 系统调节机制的结构见解。
DOI：
10.1007/s13238-016-0264-7
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发表时间：
2016-06
期刊：
影响因子：
21.1
通讯作者：
Jiang T
中科院分区：
文献类型：
--
作者：
Xu M;Yang X;Yang XA;Zhou L;Liu TZ;Fan Z;Jiang T
YfiBNR是最近在条件致病菌中发现的双-(3 ' -5 ')环二聚体GMP （c-di-GMP）信号系统。它是生物膜形成的关键调节因子，与感染的持续时间延长和抗生素耐药性有关。在细胞应激的作用下，外膜的YfiB可以隔离质周蛋白YfiR，释放其对内膜上对YfiN的抑制作用，从而激发YfiN的二胍酸环化酶活性，诱导c-二gmp的产生。然而，详细的监管机制仍然难以捉摸。在这里，我们以2:2的化学计量报告了YfiB单独和YfiBL43P与YfiR络合的活性突变体的晶体结构。结构分析显示，与单独二聚体YfiB的致密构象相反，YfiBL43P采用拉伸构象，允许活化的YfiB穿透肽聚糖（PG）层并进入YfiR。与野生型YfiB相比，YfiBL43P显示出更紧凑的PG结合口袋和更高的PG结合亲和力，表明PG结合与YfiB激活密切相关。此外，我们的晶体学分析显示，YfiR与维生素B6 （VB6）或l -色氨酸在yfib结合位点结合，VB6和l -色氨酸都能够减少yfibl43p诱导的生物膜形成。基于结构和生化数据，我们提出了一个更新的YfiBNR系统调控模型。
YfiBNR is a recently identified bis-(3’-5’)-cyclic dimeric GMP (c-di-GMP) signaling system in opportunistic pathogens. It is a key regulator of biofilm formation, which is correlated with prolonged persistence of infection and antibiotic drug resistance. In response to cell stress, YfiB in the outer membrane can sequester the periplasmic protein YfiR, releasing its inhibition of YfiN on the inner membrane and thus provoking the diguanylate cyclase activity of YfiN to induce c-di-GMP production. However, the detailed regulatory mechanism remains elusive. Here, we report the crystal structures of YfiB alone and of an active mutant YfiBL43P complexed with YfiR with 2:2 stoichiometry. Structural analyses revealed that in contrast to the compact conformation of the dimeric YfiB alone, YfiBL43P adopts a stretched conformation allowing activated YfiB to penetrate the peptidoglycan (PG) layer and access YfiR. YfiBL43P shows a more compact PG-binding pocket and much higher PG binding affinity than wild-type YfiB, suggesting a tight correlation between PG binding and YfiB activation. In addition, our crystallographic analyses revealed that YfiR binds Vitamin B6 (VB6) or L-Trp at a YfiB-binding site and that both VB6 and L-Trp are able to reduce YfiBL43P-induced biofilm formation. Based on the structural and biochemical data, we propose an updated regulatory model of the YfiBNR system.