Crystal structure of GerE, the ultimate transcriptional regulator of sporeformation in Bacillus subtilis

The small, DNA-binding protein GerE regulates gene transcription in the ter minally differentiated mother-cell compartment during late stages of sporul ation in Bacillus subtilis. This versatile transcription factor shares sequ ence homology with the LuxR/FixJ/UhpA family of activators and modulates th e expression of a number of genes, in particular those encoding the compone nts of the coat that surrounds the mature spore. GerE orchestrates the fina l stages of coat deposition and maturation that lead to a spore with remark able resistance properties but that must be responsive to low levels of ger mination signals. As this germination process is largely passive and can oc cur in the absence of de Move protein synthesis, the correct assembly of ge rmination machinery, including germinant receptors and energy storage compo unds, is crucial to the survival of the cell. The crystal structure of GerE has been solved at 2.05 Angstrom resolution using multi-wavelength anomalo us dispersion techniques and reveals the nature of the GerE dimer. Each mon omer comprises four a-helices, of which the central pair forms a helix-turn -helix DNA-binding motif. Implications for DNA-binding and the structural o rganisation of the LuxR/FixJ/UhpA family of transcription activator domains are discussed. (C) 2001 Academic Press.