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Purines in tRNAs required for recognition by ATP/CTP:tRNA nucleotidyltransferase from rabbit liver
Author(s) -
Spacciapoli Peter,
Thurlow David L.
Publication year - 1990
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/jmr.300030403
Subject(s) - transfer rna , nucleotidyltransferase , rabbit (cipher) , biochemistry , chemistry , biology , rna , computer science , gene , computer security
Recognition of tRNA by the enzyme ATP/CTP:tRNA nucleotidylransferase from rabbit liver was studied using 12 tRNAs, previously treated with the chemical modifier diethylpyrocarbonate (DEP). Such chemically modified tRNAs were labeled with 32 P by nucleotidyltransferase, using α‐[ 32 P]ATP as a cosubstrate. A carbethoxylated purine at position 57 in the Ψ‐loop interfered with recognition of the tRNA in all instances. DEP‐modified purines at other positions (58 in the Ψ‐loop, 52 or 53 in the Ψ‐stem, and 71–73 in the acceptor stem), also interfered with the interaction, but in only a few tRNAs. The mammalian enzyme was more similar to the homologous enzyme from yeast than that from bacteria, in its requirements for chemically unmodified purines. The extent of exclusion of modified bases from 32 P‐labeled material diminished as the concentration of enzyme increased, demonstrating that interference was not due to the inability of the chemically altered tRNA to refold into a recognizable conformation. The degree of purification of the enzyme did not affect the identity of bases that inhibited the reaction when modified.