Systematic deletion analysis of ricin A-chain function. Single amino acid deletions.
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.
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA.
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Munishkin
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Wool
D000595:Amino Acid Sequence; D002384:Catalysis; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009699:N-Glycosyl Hydrolases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012339:RNA, Ribosomal, 28S / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D054788:Ribosome Inactivating Proteins; D012276:Ricin / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D017384:Sequence Deletion
D012339:RNA, Ribosomal, 28S; D011994:Recombinant Proteins; D012276:Ricin; D009699:N-Glycosyl Hydrolases; D054788:Ribosome Inactivating Proteins