Fiser I, Scheit K H, Kuechler E
Eur J Biochem. 1977 Apr 15;74(3):447-56. doi: 10.1111/j.1432-1033.1977.tb11411.x.
Poly(4-thiouridylic acid) [poly(s4U)] synthesized by polymerization of 4-thiouridine 5'-diphosphate with Escherichia coli polynucleotide phosphorylase (EC 2.7.7.8) acts as messenger RNA in vitro in a protein-synthesizing system from E. coli. It stimulates binding of Phe-tRNA to ribosomes both in the presence of EF-Tu-Ts at 5 mM Mg2+ concentration and nonenzymatically at 20 mM Mg2+ concentration. It codes for the synthesis of polyphenylalanine. Poly(s4U) competes with poly(U) for binding to E. coli ribosomes. Light of 330 nm photoactivates poly(s4U) thus making it a useful photoaffinity label for the ribosomal mRNA binding site. Upon irradiation of 70-S ribosomal complexes, photoreaction occurs with ribosomal proteins as well as 16-S RNA. Ribosomes pre-incubated with R17 RNA are protected against the photoaffinity reaction. The labelling of 16-S RNA can be reduced by treatment of ribosomes with colicin E3.
由4-硫代尿苷5'-二磷酸与大肠杆菌多核苷酸磷酸化酶（EC 2.7.7.8）聚合合成的聚（4-硫代尿苷酸）[聚（s4U）]在大肠杆菌的体外蛋白质合成系统中充当信使RNA。在5 mM Mg2+浓度下存在EF-Tu-Ts时以及在20 mM Mg2+浓度下非酶促条件下，它都能刺激苯丙氨酰-tRNA与核糖体的结合。它编码多聚苯丙氨酸的合成。聚（s4U）与聚（U）竞争结合大肠杆菌核糖体。330 nm的光可使聚（s4U）光活化，因此使其成为核糖体mRNA结合位点的有用光亲和标记。照射70-S核糖体复合物时，核糖体蛋白以及16-S RNA都会发生光反应。预先与R17 RNA孵育的核糖体可免受光亲和反应的影响。用大肠菌素E3处理核糖体可减少16-S RNA的标记。
