Ian'shina D D, Malygin A A, Karpova G G
Mol Biol (Mosk). 2007 Nov-Dec;41(6):1023-30.
Human ribosomal protein (rp) S16 is a homologue of prokaryotic rpS9 that contacts the 16S rRNA region formed by helices H29, H30. H38-40, H41, H43 according to X-ray crystallography data on the 30S ribosomal subunit. In the present work, we report studying interaction of human recombinant rpS16 with a RNA transcript corresponding to the region 1203-1236/1521-1698 (helices H28-30 and H41-43) of human 18S rRNA, which is homologous to the 16S rRNA region known to bind rpS9. RpS16 was shown to specifically bind to the transcript forming a stable complex with the apparent dissociation constant of (1.3 +/- 0.1) x 10(-8) M at 20 degrees C. Nucleotide residues of the transcript that change their accessibility to RNases and modifying chemical probes upon the rpS16 binding were determined by enzymatic and chemical footprinting. It was shown that rpS16 causes significant enhancement of reactivities of nucleotides C1544 (internal loop of helix H41), C1618-U1622 and C1629-A1634 (helix H42), C1521-C1523, U1530, C1532 (helix H30) and C1645, C1646, G1648 (helix H43) and protection of nucleotides C1670-A1675 (helix H43). In the bacterial 30S ribosomal subunit many of those nucleotides of 16S rRNA that correspond to 18S rRNA nucleotides mentioned above contact rpS9 amino acid residues.
人核糖体蛋白（rp）S16是原核生物rpS9的同源物，根据30S核糖体亚基的X射线晶体学数据，它与由螺旋H29、H30、H38 - 40、H41、H43形成的16S rRNA区域相互作用。在本研究中，我们报道了对人重组rpS16与对应于人18S rRNA区域1203 - 1236/1521 - 1698（螺旋H28 - 30和H41 - 43）的RNA转录本相互作用的研究，该区域与人16S rRNA中已知与rpS9结合的区域同源。结果表明，rpS16能特异性结合该转录本，在20℃下形成稳定复合物，其表观解离常数为(1.3±0.1)×10⁻⁸ M。通过酶切和化学足迹法确定了转录本中在与rpS16结合后对核糖核酸酶和修饰化学探针的可及性发生变化的核苷酸残基。结果显示，rpS16能显著增强核苷酸C1544（螺旋H41的内环）、C1618 - U1622和C1629 - A1634（螺旋H42）、C1521 - C1523、U1530、C1532（螺旋H30）以及C1645、C1646、G1648（螺旋H43）的反应活性，并对核苷酸C1670 - A1675（螺旋H43）起到保护作用。在细菌30S核糖体亚基中，16S rRNA的许多上述对应于人18S rRNA核苷酸的核苷酸与rpS9的氨基酸残基相互作用。
