Munishkin A, Wool I G
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA.
J Biol Chem. 1995 Dec 22;270(51):30581-7. doi: 10.1074/jbc.270.51.30581.
The A-chain of ricin is a cytotoxic RNA N-glycosidase that inactivates ribosomes by depurination of the adenosine at position 4324 in 28 S rRNA. Of the 267 amino acids in the protein, 222 could be deleted, in one or another of 74 mutants, without the loss of the capacity to catalyze hydrolysis of a single specific nucleotide in rRNA (Morris, K. N., and Wool, I. G. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 4869-4873). The 45 amino acids that could not be omitted when the deletions were in sets of 20, 5, or 2 residues have now been deleted one at a time; 9 of these deletion mutants retained activity. A RNP-like structural motif in ricin A-chain that may mediate binding to ribosomal RNA has been identified.
蓖麻毒素A链是一种细胞毒性RNA N-糖苷酶，它通过使28S rRNA中第4324位的腺苷脱嘌呤来使核糖体失活。在该蛋白质的267个氨基酸中，在74个突变体中的一个或另一个中，可以删除222个氨基酸，而不会丧失催化rRNA中单个特定核苷酸水解的能力（莫里斯，K.N.，和伍尔，I.G.（1992年）美国国家科学院院刊89，4869 - 4873）。当以20、5或2个残基的组合进行缺失时不能省略的45个氨基酸，现在已一次删除一个；这些缺失突变体中有9个保留了活性。已在蓖麻毒素A链中鉴定出一种可能介导与核糖体RNA结合的RNP样结构基序。
