Crystal structure of the SOS cell division inhibitor SulA and in complex with FtsZ
- Medical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom
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Edited by Johann Deisenhofer, University of Texas Southwestern Medical Center, Dallas, TX (received for review February 7, 2003)
Abstract
SulA halts cell division in Escherichia coli by binding to the major component of the division machinery FtsZ. We have solved the crystal structure of SulA alone and in complex with FtsZ from Pseudomonas aeruginosa. SulA is expressed when the SOS response is induced. This is a mechanism to inhibit cell division and repair DNA in the event of DNA damage. FtsZ is a tubulin-like protein that forms polymers, with the active-site GTPase split across two monomers. One monomer provides the GTP-binding site and the other, through its T7 loop nucleotide hydrolysis. Our structures show that SulA is a dimer, and that SulA inhibits cell division neither by binding the nucleotide-binding site nor by inducing conformational changes in FtsZ. Instead, SulA binds the T7 loop surface of FtsZ, opposite the nucleotide-binding site, blocking polymer formation. These findings explain why GTP hydrolysis and polymer turnover are required for SulA inhibition.
Footnotes
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↵ * To whom correspondence should be addressed. E-mail: jyl{at}mrc-lmb.cam.ac.uk.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviations: MAD, multiple anomalous dispersion; PDB, Protein Data Bank.
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Data deposition: The atomic coordinates have been deposited in the Protein Data Bank, www.rcsb.org (PDB ID codes 1OFT and 1OFU).
- Copyright © 2003, The National Academy of Sciences
