JB Accepts, published online ahead of print on 30 October 2009

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Arends, S. J. R. Articles by Weiss, D. S. PubMed PubMed Citation Articles by Arends, S. J. R. Articles by Weiss, D. S.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.01244-09
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Discovery and characterization of three new Escherichia coli septal ring proteins that contain a SPOR domain: DamX, DedD and RlpA

S. J. Ryan Arends, Kyle Williams, Renada J. Scott, Silvana Rolong, David L. Popham, and David S. Weiss^*

Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA; and Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA

^* To whom correspondence should be addressed. Email: david-weiss{at}uiowa.edu.

SPOR domains are 70 a.a. long and occur in >1500 proteins identified by sequencing of bacterial genomes. The SPOR domain from the cell division protein FtsN of Escherichia coli and Caulobacter crescentus has been shown to bind peptidoglycan. Besides FtsN, E. coli has three additional SPOR domain proteins—DamX, DedD and RlpA. We show here that all three of these proteins localize to the septal ring in E. coli. Loss of DamX or DedD either alone or in combination with mutations in other division genes resulted in a variety of division phenotypes, demonstrating that DamX and DedD participate in cytokinesis. In contrast, RlpA mutants divided normally. Follow-up studies revealed that the SPOR domains themselves localize to the septal ring in vivo and bind peptidoglycan in vitro. Even SPOR domains from heterologous organisms, including Aquifex aeolicus, localized to septal rings when produced in E. coli and bound to purified E. coli peptidoglycan sacculi. We speculate that SPOR domains localize to the division site by binding preferentially to septal peptidoglycan. We further suggest that SPOR domain proteins are a common feature of the division apparatus in bacteria. DamX was characterized further and found to interact with multiple division proteins in a bacterial two-hybrid assay. One interaction partner is FtsQ, and several synthetic phenotypes suggest DamX is a negative regulator of FtsQ function.