Robert Koch Institute, FG11-Division of Bacterial Infections, Wernigerode, Germany.
J Bacteriol. 2013 Mar;195(5):1012-21. doi: 10.1128/JB.02171-12. Epub 2012 Dec 21.
DivIVA proteins are curvature-sensitive membrane binding proteins that recruit other proteins to the poles and the division septum. They consist of a conserved N-terminal lipid binding domain fused to a less conserved C-terminal domain. DivIVA homologues interact with different proteins involved in cell division, chromosome segregation, genetic competence, or cell wall synthesis. It is unknown how DivIVA interacts with these proteins, and we used the interaction of Bacillus subtilis DivIVA with MinJ and RacA to investigate this. MinJ is a transmembrane protein controlling division site selection, and the DNA-binding protein RacA is crucial for chromosome segregation during sporulation. Initial bacterial two-hybrid experiments revealed that the C terminus of DivIVA appears to be important for recruiting both proteins. However, the interpretation of these results is limited since it appeared that C-terminal truncations also interfere with DivIVA oligomerization. Therefore, a chimera approach was followed, making use of the fact that Listeria monocytogenes DivIVA shows normal polar localization but is not biologically active when expressed in B. subtilis. Complementation experiments with different chimeras of B. subtilis and L. monocytogenes DivIVA suggest that MinJ and RacA bind to separate DivIVA domains. Fluorescence microscopy of green fluorescent protein-tagged RacA and MinJ corroborated this conclusion and suggests that MinJ recruitment operates via the N-terminal lipid binding domain, whereas RacA interacts with the C-terminal domain. We speculate that this difference is related to the cellular compartments in which MinJ and RacA are active: the cell membrane and the cytoplasm, respectively.
DivIVA 蛋白是一种曲率感应的膜结合蛋白,它将其他蛋白募集到极点和分裂隔膜。它们由一个保守的 N 端脂质结合域融合到一个不太保守的 C 端结构域组成。DivIVA 同源物与参与细胞分裂、染色体分离、遗传能力或细胞壁合成的不同蛋白相互作用。目前尚不清楚 DivIVA 如何与这些蛋白相互作用,我们利用枯草芽孢杆菌 DivIVA 与 MinJ 和 RacA 的相互作用来研究这一点。MinJ 是一种跨膜蛋白,控制着分裂位点的选择,而 DNA 结合蛋白 RacA 在孢子形成过程中对染色体分离至关重要。最初的细菌双杂交实验表明,DivIVA 的 C 端似乎对招募这两种蛋白都很重要。然而,由于 C 端截断似乎也干扰了 DivIVA 的寡聚化,因此这些结果的解释受到限制。因此,采用了嵌合体方法,利用单核细胞增生李斯特菌 DivIVA 表现出正常的极定位但在枯草芽孢杆菌中表达时没有生物学活性这一事实。不同枯草芽孢杆菌和单核细胞增生李斯特菌 DivIVA 嵌合体的互补实验表明,MinJ 和 RacA 结合到分离的 DivIVA 结构域。绿色荧光蛋白标记的 RacA 和 MinJ 的荧光显微镜证实了这一结论,并表明 MinJ 的募集通过 N 端脂质结合域起作用,而 RacA 与 C 端结构域相互作用。我们推测这种差异与 MinJ 和 RacA 分别在细胞膜和细胞质中活跃的细胞区室有关。