FOLDING OF AN ENZYME INTO AN ACTIVE CONFORMATION WHILE BOUND AS PEPTIDYL-TRANSFER-RNA TO THE RIBOSOME

被引:49
作者
KUDLICKI, W
CHIRGWIN, J
KRAMER, G
HARDESTY, B
机构
[1] UNIV TEXAS,DEPT CHEM & BIOCHEM,AUSTIN,TX 78712
[2] AUDIE L MURPHY MEM VET ADM MED CTR,RES SERV,SAN ANTONIO,TX 78284
[3] UNIV TEXAS,HLTH SCI CTR,DEPT MED,SAN ANTONIO,TX 78284
[4] UNIV TEXAS,HLTH SCI CTR,DEPT BIOCHEM,SAN ANTONIO,TX 78284
关键词
D O I
10.1021/bi00044a003
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Rhodanese bound to bacterial ribosomes as peptidyl-tRNA can be folded into an enzymatically active conformation by generating C-terminal extensions of the wild-type enzyme. Rhodanese was synthesized by coupled transcription/translation in a cell-free Escherichia coli system from plasmids containing the coding sequences for the wild-type enzyme or its C-terminally extended mutants. Two proteins with extensions of 23 amino acids or longer were enzymatically active while bound to the ribosomes whereas wild-type protein and a 13-amino acid extension were not. All forms of the enzyme were active after termination and release of the full-length protein from the ribosomes. All five of the bacterial chaperones were required to substantially increase the specific enzymatic activity of the extended rhodanese while the nascent protein was bound to ribosomes. The results provide direct support for the hypothesis that proteins acquire tertiary structure as they are formed in ribosomes.
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页码:14284 / 14287
页数:4
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