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New insights into bacterial chemoreceptor array structure and assembly from electron cryotomography

Briegel, A and Wong, ML and Hodges, HL and Oikonomou, CM and Piasta, KN and Harris, MJ and Fowler, DJ and Thompson, LK and Falke, JJ and Kiessling, LL and Jensen, GJ (2014) New insights into bacterial chemoreceptor array structure and assembly from electron cryotomography. Biochemistry. pp. 1575-1585.

Abstract

Bacterial chemoreceptors cluster in highly ordered, cooperative, extended arrays with a conserved architecture, but the principles that govern array assembly remain unclear. Here we show images of cellular arrays as well as selected chemoreceptor complexes reconstituted in vitro that reveal new principles of array structure and assembly. First, in every case, receptors clustered in a trimers-of-dimers configuration, suggesting this is a highly favored fundamental building block. Second, these trimers-of-receptor dimers exhibited great versatility in the kinds of contacts they formed with each other and with other components of the signaling pathway, although only one architectural type occurred in native arrays. Third, the membrane, while it likely accelerates the formation of arrays, was neither necessary nor sufficient for lattice formation. Molecular crowding substituted for the stabilizing effect of the membrane and allowed cytoplasmic receptor fragments to form sandwiched lattices that strongly resemble the cytoplasmic chemoreceptor arrays found in some bacterial species. Finally, the effective determinant of array structure seemed to be CheA and CheW, which formed a superlattice of alternating CheA-filled and CheA-empty rings that linked receptor trimers-of-dimer units into their native hexagonal lattice. While concomitant overexpression of receptors, CheA, and CheW yielded arrays with native spacing, the CheA occupancy was lower and less ordered, suggesting that temporal and spatial coordination of gene expression driven by a single transcription factor may be vital for full order, or that array overgrowth may trigger a disassembly process. The results described here provide new insights into the assembly intermediates and assembly mechanism of this massive macromolecular complex. 2014 American Chemical Society

Item Type: Article
Additional Information: NIBR author: Wong, MJ institute: NIBR- address only contributor address: (Briegel, Jensen) Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, United States (Wong, Hodges, Kiessling) Departments of Chemistry and Biochemistry, University of Wisconsini - madison, 433 Babcock Drive, Madison, WI 53706, United States (Oikonomou, Jensen) Howard Hughes Medical Institute, 1200 East California Boulevard, Pasadena, CA 91125, United States (Piasta, Falke) Department of Chemistry and Biochemistry, Molecular Biophysics Program, University of Colorado, Boulder, CO 80309, United States (Harris, Fowler, Thompson) Department of Chemistry, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003, United States (Wong) Novartis Institutes for Biomedical Research, Cambridge, MA 02139, United States
Date Deposited: 13 Oct 2015 13:12
Last Modified: 13 Oct 2015 13:12
URI: https://oak.novartis.com/id/eprint/22644

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