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The structure of Escherichia coli ZapDThe structure of Escherichia coli ZapD
Structural highlights
FunctionZAPD_ECOLI Cell division factor that enhances FtsZ-ring assembly. Directly interacts with FtsZ and promotes bundling of FtsZ protofilaments, with a reduction in FtsZ GTPase activity.[HAMAP-Rule:MF_01092][1] Publication Abstract from PubMedBacterial cell division is an essential and highly coordinated process. It requires the polymerization of the tubulin homologue FtsZ to form a dynamic ring (Z-ring) at mid-cell. Z-ring formation relies on a group of FtsZassociatedproteins (Zap) for stability throughout the process of division. InEscherichia coli, there are currently five Zap proteins (ZapA-E), of which four (ZapA-D) are small soluble proteins that act to bind and bundle FtsZ filaments. In particular, ZapD forms a functional dimer and interacts with the C-terminal tail of FtsZ, but little is known about its structure and mechanism of action. Here, we present the crystal structure ofEscherichia coliZapD and show it forms a symmetrical dimer with centrally located alpha-helices flanked by beta-sheet domains. Based on the structure of ZapD and its chemical cross-linking to FtsZ, we targeted nine charged ZapD residues for modification by site-directed mutagenesis. Usingin vitroFtsZ sedimentation assays, we show that residues R56, R221 and R225 are important for bundling FtsZ filaments, while transmission electron microscopy revealed that altering these residues results in different FtsZ bundle morphology when compared to those bundled with wildtype ZapD. ZapD residue R116 also showed altered FtsZ bundle morphology, but similar levels of FtsZ bundling to wildtype ZapD. Together, these results reveal that ZapD residues R116, R221 and R225 likely participate in forming a positively-charged binding pocket that is critical for bundling FtsZ filaments. IMPORTANCE: Z-ring assembly underpins the formation of the essential cell division complex known as the divisome, and is required for recruitment of downstream cell division proteins. ZapD is one of several proteins inE. colithat associates with the Z-ring to promote FtsZ bundling and aid in the overall fitness of the division process. In the present study, we describe the dimeric structure ofE. coliZapD and identify residues that are critical for FtsZ bundling. Together, these results advance our understanding about the formation and dynamics of the Z-ring prior to bacterial cell division. Structure and Mutational Analysis of Escherichia coli ZapD Reveals Charged Residues Involved in FtsZ Filament Bundling.,Roach EJ, Wroblewski C, Seidel L, Berezuk AM, Brewer D, Kimber MS, Khursigara CM J Bacteriol. 2016 Mar 28. pii: JB.00969-15. PMID:27021560[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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