Grenha Rosa, Rzechorzek Neil J, Brannigan James A, de Jong Rob N, Ab Eiso, Diercks Tammo, Truffault Vincent, Ladds Joanne C, Fogg Mark J, Bongiorni Cristina, Perego Marta, Kaptein Robert, Wilson Keith S, Folkers Gert E, Wilkinson Anthony J
Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, United Kingdom.
J Biol Chem. 2006 Dec 8;281(49):37993-8003. doi: 10.1074/jbc.M607617200. Epub 2006 Sep 25.
Spore formation is an extreme response of many bacterial species to starvation. In the case of pathogenic species of Bacillus and Clostridium, it is also a component of disease transmission. Entry into the pathway of sporulation in Bacillus subtilis and its relatives is controlled by an expanded two-component system in which starvation signals lead to the activation of sensor kinases and phosphorylation of the master sporulation response regulator Spo0A. Accumulation of threshold concentrations of Spo0A approximately P heralds the commitment to sporulation. Countering the activities of the sensor kinases are phosphatases such as Spo0E, which dephosphorylate Spo0A approximately P and inhibit sporulation. Spo0E-like protein-aspartic acid-phosphate phosphatases, consisting of 50-90 residues, are conserved in sporeforming bacteria and unrelated in sequence to proteins of known structure. Here we determined the structures of the Spo0A approximately P phosphatases BA1655 and BA5174 from Bacillus anthracis using nuclear magnetic resonance spectroscopy. Each is composed of two anti-parallel alpha-helices flanked by flexible regions at the termini. The signature SQELD motif (SRDLD in BA1655) is situated in the middle of helix alpha2 with its polar residues projecting outward. BA5174 is a monomer, whereas BA1655 is a dimer. The four-helix bundle structure in the dimer is reminiscent of the phosphotransferase Spo0B and the chemotaxis phosphatase CheZ, although in contrast to these systems, the subunits in BA1655 are in head-to-tail rather than head-to-head apposition. The implications of the structures for interactions between the phosphatases and their substrate Spo0A approximately P are discussed.
孢子形成是许多细菌物种在饥饿时的一种极端反应。对于芽孢杆菌属和梭菌属的致病物种而言，它也是疾病传播的一个组成部分。枯草芽孢杆菌及其相关菌进入孢子形成途径是由一个扩展的双组分系统控制的，在这个系统中，饥饿信号导致传感激酶的激活以及主孢子形成反应调节因子Spo0A的磷酸化。Spo0AP阈值浓度的积累预示着对孢子形成的确定。与传感激酶的活性相反的是磷酸酶，如Spo0E，它使Spo0AP去磷酸化并抑制孢子形成。Spo0E样蛋白 - 天冬氨酸 - 磷酸磷酸酶由50 - 90个残基组成，在形成孢子的细菌中保守，并且在序列上与已知结构的蛋白质无关。在这里，我们使用核磁共振光谱法确定了炭疽芽孢杆菌中Spo0AP磷酸酶BA1655和BA5174的结构。每一种都由两个反平行的α螺旋组成，两端为柔性区域。标志性的SQELD基序（在BA1655中为SRDLD）位于α2螺旋的中间，其极性残基向外突出。BA5174是单体，而BA1655是二聚体。二聚体中的四螺旋束结构让人联想到磷酸转移酶Spo0B和趋化磷酸酶CheZ，尽管与这些系统不同，BA1655中的亚基是头对尾而非头对头排列。文中讨论了这些结构对于磷酸酶与其底物Spo0AP之间相互作用的影响。
