title: Caulobacter PopZ forms an intrinsically disordered hub in organizing bacterial cell poles.
abstract: Despite their relative simplicity, bacteria have complex anatomy at the subcellular level. At the cell poles of Caulobacter crescentus, a 177-amino acid (aa) protein called PopZ self-assembles into 3D polymeric superstructures. Remarkably, we find that this assemblage interacts directly with at least eight different proteins, which are involved in cell cycle regulation and chromosome segregation. The binding determinants within PopZ include 24 aa at the N terminus, a 32-aa region near the C-terminal homo-oligomeric assembly domain, and portions of an intervening linker region. Together, the N-terminal 133 aa of PopZ are sufficient for interacting with all binding partners, even in the absence of homo-oligomeric assembly. Structural analysis of this region revealed that it is intrinsically disordered, similar to p53 and other hub proteins that organize complex signaling networks in eukaryotic cells. Through live-cell photobleaching, we find rapid binding kinetics between PopZ and its partners, suggesting many pole-localized proteins become concentrated at cell poles through rapid cycles of binding and unbinding within the PopZ scaffold. We conclude that some bacteria, similar to their eukaryotic counterparts, use intrinsically disordered hub proteins for network assembly and subcellular organization.
authors: Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.
authors: Joshua A
authors: JA
authors: Holmes
authors: Department of Chemistry, University of Wyoming, Laramie, WY 82071.
authors: Shelby E
authors: SE
authors: Follett
authors: Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.
authors: Haibi
authors: H
authors: Wang
authors: Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.
authors: Christopher P
authors: CP
authors: Meadows
authors: Department of Chemistry, University of Wyoming, Laramie, WY 82071.
authors: Krisztina
authors: K
authors: Varga
authors: Department of Molecular Biology, University of Wyoming, Laramie, WY 82071; grant.bowman@uwyo.edu.
authors: Grant R
authors: GR
authors: Bowman
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D064267:Intrinsically Disordered Proteins / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008856:Microscopy, Fluorescence; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D001426:Bacterial Proteins; D064267:Intrinsically Disordered Proteins
keywords: Caulobacter; PopZ; bacteria; hub protein; intrinsically disordered protein