DNA-binding studies on the Bacillus subtilis transcriptional regulator and AbrB homologue, SpoVT

The process of spore formation in Bacillus subtilis is dependent upon a sophisticated program of gene expression that is regulated both temporally and spatially by a series of alternate sigma factors, in conjunction with a number of transcriptional regulators. One of these, SpoVT, regulates forespore-specific sigmaG-dependent transcription and is related at the amino acid level to the major stationary phase sentinel, AbrB, whose mode of DNA recognition appears to be non-classical. Here, we report that the C-terminal domain of SpoVT is crucial to its correct folding and function, and how the DNA-binding domain from AbrB cannot complement the closely homologous domain of SpoVT in vivo. We also establish the oligomeric state of SpoVT and its component domains. Finally, we demonstrate that the regulation of transcriptional control by SpoVT is unexpectedly more complicated than its counterpart, AbrB, and that the latent non-specific DNA-binding activity of the N-terminal domain of SpoVT is modulated by the C-terminal domain, which perhaps in combination with another unknown factor, confers specificity.