A conserved coiled‐coil protein pair focuses the cytokinetic Z‐ring in Caulobacter crescentus

• Published in: Molecular microbiology 2017-09, Vol.105 (5), p.721-740
• Main Authors: Woldemeskel, Selamawit Abi, McQuillen, Ryan, Hessel, Alex M., Xiao, Jie, Goley, Erin D.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacteria; Bacterial proteins; Bacterial Proteins - metabolism; Bundling; Carrier Proteins - genetics; Carrier Proteins - metabolism; Caulobacter crescentus - genetics; Caulobacter crescentus - metabolism; Cell Cycle Proteins - metabolism; Cell Division; Coding; Coils; Cytokinesis; Cytokinesis - genetics; Cytokinesis - physiology; Cytoskeletal Proteins - metabolism; Cytoskeleton; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gram-negative bacteria; Guanosine triphosphatases; In vitro methods and tests; Machinery and equipment; Microscopy, Fluorescence; Models, Molecular; Operon - genetics; Polymerization; Protein Binding; Protein Structure, Tertiary
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.13731

Summary The cytoskeletal GTPase FtsZ assembles at midcell, recruits the division machinery and directs envelope invagination for bacterial cytokinesis. ZapA, a conserved FtsZ‐binding protein, promotes Z‐ring stability and efficient division through a mechanism that is not fully understood. Here, we investigated the function of ZapA in Caulobacter crescentus. We found that ZapA is encoded in an operon with a small coiled‐coil protein we named ZauP. ZapA and ZauP co‐localized at the division site and were each required for efficient division. ZapA interacted directly with both FtsZ and ZauP. Neither ZapA nor ZauP influenced FtsZ dynamics or bundling, in vitro, however. Z‐rings were diffuse in cells lacking zapA or zauP and, conversely, FtsZ was enriched at midcell in cells overproducing ZapA and ZauP. Additionally, FtsZ persisted at the poles longer when ZapA and ZauP were overproduced, and frequently colocalized with MipZ, a negative regulator of FtsZ polymerization. We propose that ZapA and ZauP promote efficient cytokinesis by stabilizing the midcell Z‐ring through a bundling‐independent mechanism. The zauPzapA operon is present in diverse Gram‐negative bacteria, indicating a common mechanism for Z‐ring assembly. We have identified a protein, ZauP, that is encoded in an operon with ZapA in Caulobacter crescentus. ZapA and ZauP are required for efficient cytokinesis and directly interact with each other. ZapA binds FtsZ and ZapA and ZauP together focus the Z‐ring at midcell through a bundling‐independent mechanism. ZauP is conserved in diverse Gram‐negative bacteria.