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Formation of SRP‐like particle induces a conformational change in E. coli 4.5S RNA
Author(s) -
Lentzen Georg,
Dobberstein Bernhard,
Wintermeyer Wolfgang
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00599-0
Subject(s) - rna , chemistry , biophysics , fluorescence anisotropy , dissociation constant , biochemistry , microbiology and biotechnology , biology , membrane , gene , receptor
E. coli P48 protein is homologous to the SRP54 component of the eukaryotic signal recognition particle. In vivo, P48 is associated with 4.5S RNA which shares a homology with eukaryotic SRP RNA. To study the interaction between P48 and 4.5S RNA in vitro, we used 4.5S RNA with fluorescein coupled to the 3′‐terminal ribose. Upon binding of P48, the fluorescent 4.5S RNA shows a substantial decrease in fluorescence. Fluorescence quenching as well as anisotropy measurements reveal that the effect is not due to a direct interaction of P48 with the dye. This suggests that the binding of P48 induces a conformational change in 4.5S RNA which affects the structure at the 3′ end of the RNA. From equilibrium titrations with fluorescent 4.5S RNA, a dissociation constant of O.15 μm is obtained for the RNA · protein complex. The formation of the complex is not affected by GTP binding to or hydrolysis by P48.