Escherichia coli sigma 70 and NusA proteins. II. Physical properties and self-association states.
In this paper we examine the physical properties and potential for self-association of the Escherichia coli transcription factors, sigma 70 and NusA. We show, by a combination of chemical crosslinking, equilibrium and velocity sedimentation, quasi-elastic light scattering, and small-angle X-ray scattering that NusA exists as a monomer at KCl concentrations between 0.01 and 1.5 M, and that sigma 70 exists as a monomer at KCl concentrations between 0.1 and 1.5 M. The shape and hydration characteristics of each of these monomeric proteins are also examined. The results serve as background for the companion paper in which a thermodynamic analysis is made of the interactions of these transcription factor with E. coli core RNA polymerase in solution and as a component of the functional transcription complex.
Gill
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SC
Institute of Molecular Biology, University of Oregon, Eugene 97403.
Yager
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TD
von Hippel
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PH
D001426:Bacterial Proteins / Q000737:chemistry*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008027:Light; D046911:Macromolecular Substances; D008433:Mathematics; D008962:Models, Theoretical; D009994:Osmolar Concentration; D010445:Peptide Elongation Factors; D011485:Protein Binding; D012542:Scattering, Radiation; D012808:Sigma Factor / Q000737:chemistry* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry*; D035602:Transcriptional Elongation Factors; D014961:X-Ray Diffraction
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D010445:Peptide Elongation Factors; D012808:Sigma Factor; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; C068727:nusA protein, E coli