Crystal Structure of SpoVT, the Final Modulator of Gene Expression during Spore Development in Bacillus subtilis

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• 作者：Iris Asen ; Sergej Djuranovic ; Andrei N. Lupas ; Kornelius Zeth
• 关键词：SpoVT ; sporulation ; transcription factor ; AbrB ; GAF domain
• 刊名：Journal of Molecular Biology
• 出版年：2009
• 出版时间：6 March 2009
• 年：2009
• 卷：386
• 期：4
• 页码：962-975
• 全文大小：1242 K

文摘

Endospore formation in Bacillus subtilis is orchestrated by five developmental sigma factors and further modulated by several auxiliary transcription factors. One of these, SpoVT, regulates forespore-specific σ^G-dependent genes and plays a key role in the final stages of spore formation. We have determined the crystal structure of the isolated C-terminal domain of SpoVT at 1.5 Å by experimental phasing techniques and used this model to solve the structure of the full-length SpoVT at 2.6 Å by molecular replacement. SpoVT is a tetramer that shows an overall significant distortion mediated by electrostatic interactions. Two monomers dimerize via the highly charged N-terminal domains to form swapped-hairpin β-barrels. These asymmetric dimers further tetramerize through the formation of mixed helix bundles between their C-terminal domains, which themselves fold as GAF (cGMP-specific and cGMP-stimulated phosphodiesterases, Anabaena adenylate cyclases, and Escherichia coli FhlA) domains. The combination of a swapped-hairpin β-barrel with a GAF domain represents a novel domain architecture in transcription factors. The occurrence of SpoVT homologs throughout Bacilli and Clostridia demonstrates the ancestral origin of this factor in sporulation.