Tanner Andrew W, Carabetta Valerie J, Martinie Ryan J, Mashruwala Ameya A, Boyd Jeffrey M, Krebs Carsten, Dubnau David
Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA.
Public Health Research Institute Center, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA.
Mol Microbiol. 2017 Jun;104(5):837-850. doi: 10.1111/mmi.13667. Epub 2017 Apr 6.
During times of environmental insult, Bacillus subtilis undergoes developmental changes leading to biofilm formation, sporulation and competence. Each of these states is regulated in part by the phosphorylated form of the master response regulator Spo0A (Spo0A∼P). The phosphorylation state of Spo0A is controlled by a multi-component phosphorelay. RicA, RicF and RicT (previously YmcA, YlbF and YaaT) have been shown to be important regulatory proteins for multiple developmental fates. These proteins directly interact and form a stable complex, which has been proposed to accelerate the phosphorelay. Indeed, this complex is sufficient to stimulate the rate of phosphotransfer amongst the phosphorelay proteins in vitro. In this study, we demonstrate that two [4Fe-4S] clusters can be assembled on the complex. As with other iron-sulfur cluster-binding proteins, the complex was also found to bind FAD, hinting that these cofactors may be involved in sensing the cellular redox state. This work provides the first comprehensive characterization of an iron-sulfur protein complex that regulates Spo0A∼P levels. Phylogenetic and genetic evidence suggests that the complex plays a broader role beyond stimulation of the phosphorelay.
在遭受环境损伤时，枯草芽孢杆菌会发生发育变化，导致生物膜形成、孢子形成和感受态。这些状态中的每一种都部分受主反应调节因子Spo0A的磷酸化形式（Spo0A∼P）调控。Spo0A的磷酸化状态由多组分磷酸传递系统控制。RicA、RicF和RicT（以前称为YmcA、YlbF和YaaT）已被证明是多种发育命运的重要调节蛋白。这些蛋白直接相互作用并形成稳定的复合物，有人提出该复合物可加速磷酸传递。实际上，该复合物足以在体外刺激磷酸传递蛋白之间的磷酸转移速率。在本研究中，我们证明可以在该复合物上组装两个[4Fe-4S]簇。与其他铁硫簇结合蛋白一样，该复合物也被发现结合FAD，这表明这些辅因子可能参与感知细胞氧化还原状态。这项工作首次全面表征了一种调节Spo0A∼P水平的铁硫蛋白复合物。系统发育和遗传学证据表明，该复合物在刺激磷酸传递之外还发挥着更广泛的作用。
