A Caltech Library Service

Physical Properties of the Escherichia coli Transcription Termination Factor Rho. 1. Association States and Geometry of the Rho Hexamer

Geiselmann, Johannes and Yager, Thomas D. and Gill, Stanley C. and Calmettes, Patrick and von Hippel, Peter H. (1992) Physical Properties of the Escherichia coli Transcription Termination Factor Rho. 1. Association States and Geometry of the Rho Hexamer. Biochemistry, 31 (1). pp. 111-121. ISSN 0006-2960. doi:10.1021/bi00116a017.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


To function as a DNA-RNA helicase in rho-dependent transcript termination, six genetically identical subunits of the Escherichia coli transcription termination protein rho must first assemble into a hexameric complex. To help determine the quaternary structure of this complex, we have studied the association equilibria of the rho protomers. Sedimentation equilibrium, sedimentation velocity, diffusion, X-ray scattering, and neutron-scattering data have been combined to create a “phase diagram” of the association states of this protein as a function of protein concentration and ionic environment. The results show that rho exists predominantly as a hexamer under approximately hysiological conditions and that this hexamer is in equilibrium with both lower and higher states of association that may also have physiologicial relevance. Small-angle X-ray scattering measurements and theoretical calculations indicate that the rho hexamer has a radius of gyration of 50 ± 3 Å. The radius of gyration measured by small-angle neutron scattering in ^2H_2O is 47 ± 3 Å. These scattering studies also support earlier models of rho as a planar hexagon which have been developed on the basis of electron microscopy. In the following paper in this issue [Geiselmann, J., Seifried, S. E., Yager, T. D., Liang, C., & von Hippel, P. H. (1992)], these results are combined with information on symmetry, subunit interactions, and packing geometry to obtain a model of the quaternary structure of the functional rho hexamer.

Item Type:Article
Related URLs:
URLURL TypeDescription
Additional Information:© 1992 American Chemical Society. Published in print 14 January 1992. This work has been submitted (by J.G.) to the Graduate school of the University of Oregon in partial fulfillment of the requirements for the Ph.D. degree of Chemistry. These studies were supported in part by USPHS Research Grants GM-15792 and GM-29158 (to P.H.v.H.), by NIH Individual Postdoctoral Fellowship GM-10227 (to T.D.Y.), and by a grant from the Lucille P. Markey Charitable Trust. P.H.v.H. is an American Cancer Society Research Professor of Chemistry. We thank the Biotechnology Laboratory of the University of Oregon for synthesis of (dC),o and (dC),, the Shared Laser Facility of the University of Oregon for use of QLS equipment, and Dr. K. E. Van Holde (Oregon State University) for the use of his model E analytical ultracentrifuge. We also thank Drs. Patrice Vachette and Annette Tardieu for help with the experiments at LURE and for preliminary model calculations of the high-angle X-ray scattering curves in terms of hexamers and dodecamers. In addition, we are grateful to Drs. John Schellman (University of Oregon) and Henryk Eisenberg (Weizmann Institute) for advice on densimetry measurements, to Dr. Guiseppe Zaccai of the Institut Laue-Langevin in Grenoble, France, for discussion of scattering experiments, to Dr. Walter Baase of the University of Oregon for discussion of QLS experiments, and to Dr. Stanley J. Gill (deceased) of the University of Colorado for discussion of self-associating macromolecular systems.
Funding AgencyGrant Number
NIH Postdoctoral FellowshipGM-10227
Lucille P. Markey Charitable TrustUNSPECIFIED
American Cancer SocietyUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20180207-075828535
Persistent URL:
Official Citation:Physical properties of the Escherichia coli transcription termination factor rho. 1. Association states and geometry of the rho hexamer Johannes Geiselmann, Thomas D. Yager, Stanley C. Gill, Patrick Calmettes, and Peter H. Von Hippel Biochemistry 1992 31 (1), 111-121 DOI: 10.1021/bi00116a017
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84700
Deposited By: Ruth Sustaita
Deposited On:07 Feb 2018 16:30
Last Modified:15 Nov 2021 20:22

Repository Staff Only: item control page