Ducros V M, Lewis R J, Verma C S, Dodson E J, Leonard G, Turkenburg J P, Murshudov G N, Wilkinson A J, Brannigan J A
Structural Biology Laboratory Department of Chemistry, University of York, Heslington, YO10 5DD, UK.
J Mol Biol. 2001 Mar 2;306(4):759-71. doi: 10.1006/jmbi.2001.4443.
The small, DNA-binding protein GerE regulates gene transcription in the terminally differentiated mother-cell compartment during late stages of sporulation in Bacillus subtilis. This versatile transcription factor shares sequence homology with the LuxR/FixJ/UhpA family of activators and modulates the expression of a number of genes, in particular those encoding the components of the coat that surrounds the mature spore. GerE orchestrates the final stages of coat deposition and maturation that lead to a spore with remarkable resistance properties but that must be responsive to low levels of germination signals. As this germination process is largely passive and can occur in the absence of de novo protein synthesis, the correct assembly of germination machinery, including germinant receptors and energy storage compounds, is crucial to the survival of the cell. The crystal structure of GerE has been solved at 2.05 A resolution using multi-wavelength anomalous dispersion techniques and reveals the nature of the GerE dimer. Each monomer comprises four alpha-helices, of which the central pair forms a helix-turn-helix DNA-binding motif. Implications for DNA-binding and the structural organisation of the LuxR/FixJ/UhpA family of transcription activator domains are discussed.
小的DNA结合蛋白GerE在枯草芽孢杆菌芽孢形成后期，对终末分化的母细胞区室中的基因转录进行调控。这个多功能转录因子与LuxR/FixJ/UhpA家族激活剂具有序列同源性，并调节许多基因的表达，特别是那些编码围绕成熟芽孢的芽孢衣成分的基因。GerE协调芽孢衣沉积和成熟的最后阶段，形成具有显著抗性的芽孢，但芽孢必须对低水平的萌发信号作出反应。由于这种萌发过程在很大程度上是被动的，并且可以在没有从头合成蛋白质的情况下发生，因此萌发机制（包括萌发受体和储能化合物）的正确组装对细胞存活至关重要。利用多波长反常色散技术，已解析出分辨率为2.05 Å的GerE晶体结构，并揭示了GerE二聚体的性质。每个单体由四个α螺旋组成，其中央一对形成一个螺旋-转角-螺旋DNA结合基序。文中讨论了对DNA结合以及LuxR/FixJ/UhpA家族转录激活域结构组织的影响。
