Malonga Herman, Neault Jean-Francois, Tajmir-Riahi Heidar-Ali
Department of Chemistry-Biology, University of Québec at Trois-Rivières, Québec, Canada.
DNA Cell Biol. 2006 Jul;25(7):393-8. doi: 10.1089/dna.2006.25.393.
Protein-RNA complexation is essential in cell biological functions. Transfer RNAs are bound to aminoacyl-tRNA synthetases for the translation of the genetic code during protein synthesis, while ribonucleoproteins bind RNA in posttranscriptional regulation of gene expression. A recent report showed the interacton of human serum albumin (HSA) with DNA duplex, in which two binding sites with strong and weak association constants were detected. We now examine the interaction of tRNA with human serum albumin (HSA) in aqueous solution at physiological conditions, using a constant RNA concentration of 12.5 mM (phosphate) and various HSA contents of 0.04 to 0.6 mM. Affinity capillary electrophoresis and FTIR spectroscopic methods were used to determine the protein binding mode, the association constant, sequence preference, and the biopolymer secondary structural changes in the HSA-RNA complexes. Spectroscopic evidence showed two types of HSA-RNA complexes with an overall binding constant of K = 1.45 x 10(4) M(-1). The major binding sites were located on the G-C bases and the backbone PO2 group. The protein-RNA interaction stabilizes the HSA secondary structure, and no major alterations of A-RNA structure or protein conformation occurred.
蛋白质 - RNA 复合作用在细胞生物学功能中至关重要。在蛋白质合成过程中，转运RNA与氨酰 - tRNA合成酶结合以进行遗传密码的翻译，而核糖核蛋白在基因表达的转录后调控中与RNA结合。最近的一份报告显示了人血清白蛋白（HSA）与DNA双链体的相互作用，其中检测到了两个具有强关联常数和弱关联常数的结合位点。我们现在在生理条件下的水溶液中研究tRNA与人血清白蛋白（HSA）的相互作用，使用恒定的RNA浓度12.5 mM（磷酸盐）和0.04至0.6 mM的各种HSA含量。采用亲和毛细管电泳和傅里叶变换红外光谱方法来确定蛋白质的结合模式、结合常数、序列偏好以及HSA - RNA复合物中生物聚合物二级结构的变化。光谱证据表明存在两种类型的HSA - RNA复合物，其总结合常数K = 1.45×10⁴ M⁻¹。主要结合位点位于G - C碱基和主链PO₂基团上。蛋白质 - RNA相互作用稳定了HSA的二级结构，并且A - RNA结构或蛋白质构象没有发生重大改变。
