Michalska Karolina, Chhor Gekleng, Clancy Shonda, Jedrzejczak Robert, Babnigg Gyorgy, Winans Stephen C, Joachimiak Andrzej
Midwest Center for Structural Genomics, Argonne National Laboratory, IL, USA; Structural Biology Center, Biosciences Division, Argonne National Laboratory, IL, USA.
FEBS J. 2014 Sep;281(18):4293-306. doi: 10.1111/febs.12868. Epub 2014 Jul 4.
Burkholderia cepacia complex is a set of closely related bacterial species that are notorious pathogens of cystic fibrosis patients, responsible for life-threatening lung infections. Expression of several virulence factors of Burkholderia cepacia complex is controlled by a mechanism known as quorum sensing (QS). QS is a means of bacterial communication used to coordinate gene expression in a cell-density-dependent manner. The system involves the production of diffusible signaling molecules (N-acyl-l-homoserine lactones, AHLs), that bind to cognate transcriptional regulators and influence their ability to regulate gene expression. One such system that is highly conserved in Burkholderia cepacia complex consists of CepI and CepR. CepI is AHL synthase, whereas CepR is an AHL-dependent transcription factor. In most members of the Burkholderia cepacia complex group, the cepI and cepR genes are divergently transcribed and separated by additional genes. One of them, bcam1869, encodes the BcRsaM protein, which was recently postulated to modulate the abundance or activity of CepI or CepR. Here, we show the crystal structure of BcRsaM from B. cenocepacia J2315. It is a single-domain protein with unique topology and presents a novel fold. The protein is a dimer in the crystal and in solution. This regulator has no known DNA-binding motifs and direct binding of BcRsaM to the cepI promoter could not be detected in in vitro assays. Therefore, we propose that the modulatory action of RsaM might result from interactions with other components of the QS machinery rather than from direct association with the DNA promoter.
The atomic coordinates and structure factors have been deposited in the Protein Data Bank under entry 4O2H.
BcRsaM and BcRsaM bind by x-ray crystallography (View interaction) BcRsaM and BcRsaM bind by molecular sieving (View interaction).
洋葱伯克霍尔德菌复合体是一组密切相关的细菌物种，是囊性纤维化患者臭名昭著的病原体，可导致危及生命的肺部感染。洋葱伯克霍尔德菌复合体的几种毒力因子的表达受一种称为群体感应（QS）的机制控制。群体感应是一种细菌通讯方式，用于以细胞密度依赖的方式协调基因表达。该系统涉及可扩散信号分子（N-酰基-L-高丝氨酸内酯，AHLs）的产生，这些分子与同源转录调节因子结合并影响它们调节基因表达的能力。在洋葱伯克霍尔德菌复合体中高度保守的一个这样的系统由CepI和CepR组成。CepI是AHL合酶，而CepR是一种依赖AHL的转录因子。在洋葱伯克霍尔德菌复合体组的大多数成员中，cepI和cepR基因反向转录，并由其他基因隔开。其中一个基因bcam1869编码BcRsaM蛋白，最近推测该蛋白可调节CepI或CepR的丰度或活性。在这里，我们展示了来自洋葱伯克霍尔德菌J2315的BcRsaM的晶体结构。它是一种具有独特拓扑结构的单结构域蛋白，呈现出一种新颖的折叠方式。该蛋白在晶体和溶液中均为二聚体。这种调节因子没有已知的DNA结合基序，并且在体外试验中未检测到BcRsaM与cepI启动子的直接结合。因此，我们提出RsaM的调节作用可能是由于与QS机制的其他成分相互作用，而不是与DNA启动子直接结合。
原子坐标和结构因子已存入蛋白质数据库，登录号为4O2H。
BcRsaM和BcRsaM通过X射线晶体学结合（查看相互作用），BcRsaM和BcRsaM通过分子筛结合（查看相互作用）。
