The mutual effect of human ribosomal proteins S5 and S16 on their binding with 18S rRNA fragment 1203–1236/1521–1698

Human ribosomal proteins S5 and S16 (hrpS5 and hrpS16) are homologous, respectively, to prokaryotic ribosomal proteins S7p and S9p, which, according to X-ray crystallography data on the Thermus thermophilus 30S ribosomal subunit, contact the 3′-terminal 16S rRNA region formed by helices H28–H30 and H38–H43. Footprinting was used to study the mutual effect of hrpS5 and hrpS16 on their binding with an RNA transcript corresponding to 18S rRNA region 1203–1236/1521–1698 (helices H28–30 and H41–43), which is homologous to the16S rRNA region known to contain the binding site for S7p and part of the binding site for S9p. A simultaneous binding of hrpS5 and hrpS16 with the RNA transcript was shown to cause RNA conformational changes that stabilized the complex by involving new RNA parts, which did not interact with hrpS5 or hrpS16 in the respective binary complexes.