Structure of the Phosphatase Domain of the Cell Fate Determinant SpoIIE from Bacillus subtilis

Vladimir M. Levdikov, Elena V. Blagova, Andrea E. Rawlings, Katie Jameson, James Tunaley, Darren J. Hart, Imrich Barak, Anthony J. Wilkinson

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Sporulation in Bacillus subtilis begins with an asymmetric cell division producing two genetically identical cells with different fates. SpoIIE is a membrane protein that localizes to the polar cell division sites where it causes FtsZ to relocate from mid-cell to form polar Z-rings. Following polar septation, SpoIIE establishes compartment-specific gene expression in the smaller forespore cell by dephosphorylating the anti-sigma factor antagonist SpoIIAA, leading to the release of the RNA polymerase sigma factor sigma(F) from an inhibitory complex with the anti-sigma factor SpoIIAB. SpoIIE therefore couples morphological development to differential gene expression. Here, we determined the crystal structure of the phosphatase domain of SpoIIE to 2.6 angstrom spacing, revealing a domain-swapped dimer. SEC-MALLS (size-exclusion chromatography with multi-angle laser light scattering) analysis however suggested a monomer as the principal form in solution. A model for the monomer was derived from the domain-swapped dimer in which 2 five-stranded beta-sheets are packed against one another and flanked by alpha-helices in an alpha beta beta alpha arrangement reminiscent of other PP2C-type phosphatases. A flap region that controls access of substrates to the active site in other PP2C phosphatases is diminished in SpoIIE, and this observation correlates with the presence of a single manganese ion in the active site of SpoIIE in contrast to the two or three metal ions present in other PP2C enzymes. Mapping of a catalogue of mutational data onto the structure shows a clustering of sites whose point mutation interferes with the proper coupling of asymmetric septum formation to sigma factor activation and identifies a surface involved in intramolecular signaling. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)343-358
Number of pages16
JournalJournal of Molecular Biology
Issue number2
Publication statusPublished - 13 Jan 2012

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