TEMPLATE-FREE RIBOSOMAL SYNTHESIS OF POLYPEPTIDES FROM AMINOACYL-TRANSFER RNAS
TEMPLATE-FREE RIBOSOMAL SYNTHESIS OF POLYPEPTIDES FROM AMINOACYL-TRANSFER RNAS
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DOI：
10.1016/0303-2647(82)90008-9
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发表时间：
1982-01-01
期刊：
影响因子：
1.6
通讯作者：
SPIRIN, AS
中科院分区：
文献类型：
--
作者：
BELITSINA, NV;TNALINA, GZ;SPIRIN, AS
大肠杆菌核糖体在缺少信使多核苷酸的情况下能够以氨酰-tRNA为底物合成一些多肽。EF-Tu诱导的氨酰-tRNA结合、核糖体肽基转移酶和EF-G促进的易位是这种无模板延伸的严格要求。典型的核糖体抑制剂如四环素、氯霉素、苯硼酸和夫西地酸抑制多肽的无模板合成。该合成需要GTP裂解; GTP的不可裂解类似物鸟苷基-5 ''-基亚甲基二膦酸酯不能维持合成。在所研究的16种氨酰-tRNA中，以Lys-tRNA、Ser-tRNA、Thr-tRNA和Asp-tRNA为最佳底物。Gly-tRNA、Glu-tRNA、Val-tRNA、Arg-tRNA、Ala-tRNA和Leu-tRNA作为底物，在非程序化核糖体上的多肽合成水平相对较低。Pro-tRNA、Phe-tRNA、Asn-tRNA、Met-tRNA、Ile-tRNA和Gln-tRNA作为无模板延伸的底物几乎没有活性。氨酰-tRNA作为无模板延伸底物的能力与其与核糖体无模板结合的活性之间没有相关性。
Escherichia coli ribosomes in the absence of messenger polynucleotides are capable of synthesizing some polypeptides from aminoacyl-tRNA as substrates. EF-Tu induced binding of aminoacyl-tRNA, ribosomal peptidyl transferase and EF-G-promoted translocation are strictly required for this template-free elongation. Typical ribosomal inhibitors such as tetracycline, chloramphenicol, phenylboric acid and fusidic acid inhibit the template-free synthesis of polypeptides. The synthesis requires GTP cleavage; a non-cleavable analog of GTP, guanyl-5''-yl methylenediphosphonate does not maintain the synthesis. Among 16 different aminoacyl-tRNA studied as substrates for the ribosomal template-free synthesis of polypeptides Lys-tRNA, Ser-tRNA, Thr-tRNA and Asp-tRNA were the best. Gly-tRNA, Glu-tRNA, Val-tRNA, Arg-tRNA, Ala-tRNA and Leu-tRNA as substrates gave relatively low levels of the polypeptide synthesis on non-programmed ribosomes. Pro-tRNA, Phe-tRNA, Asn-tRNA, Met-tRNA, Ile-tRNA and Gln-tRNA were practically inactive as substrates for the template-free elongation. No correlation was found between the abilities of the aminoacyl-tRNA to serve as substrates for the template-free elongation and their activities in template-free binding to ribosomes.