Nucleic Acids Research, 1978, Vol. 5, No. 10 3579-3588
© 1978
Articles |
Small-angle X-ray titration of the complex formed between the ribosomal protein S4 and its 16S binding site, S4-RNA: a central core in the 30S subunit
Department of Medical Biochemistry, University of Göteborg Fack, S-400 33 Göteborg, Sweden Max-Planck-Institut für Molekulare Genetik (Abt. Wittmann) Berlin, GFR
* To whom correspondence should be addressed
Received July 4, 1978.
X-ray scattering titrations at 21°C and in ribosomal reconstitution buffer indicate that the S4-RNA and the protein S4 form a 1:1 complex with a stability constant, log K 
6.5. When the complex forms, there is only a limited change in the scattering curve indicating that S4-RNA essentially retains its conformation during the complex formation. The increase in the gyration radius as a result of the complex formation, 
R = 4 ± 3 Å, as well as the experimental scattering curve of the complex can be explained by models where the protein S4 is supposed to interact with the periphery of the S4-RNA.