A novel ribotoxin with ribonuclease activity that specifically cleaves a single phosphodiester bond in rat 28S ribosomal RNA and inactivates ribosome.
A unique ribonuclease named Biota orientalis ribonuclease (Biota orientalis RNase) is purified to homogeneity from mature seeds of oriental arborvitae (Biota orientalis). The molecular mass of Biota orientalis RNase is about 13 kDa. When the concentration of Mg(2+) is 25 mM in the incubation buffer, the ribonuclease specifically cleaves the phosphodiester bond between C4453 and A4454 in region K (a region in domain VII) of 28S RNA in rat ribosome, resulting in inactivation of ribosome. Thus, it is a ribotoxin similar to alpha-sarcin. The region around C4453-A4454 in rat 28S rRNA is named "Biota orientalis RNase region." Rat ribosome treated by Biota orientalis RNase produces a small RNA fragment (S-fragment) that contains 333 nucleotides from the 3'-terminus of rat 28S rRNA. The distance between the cleavage-sites of alpha-sarcin (G4325) and Biota orientalis RNase (C4453) is 128 nucleotides. Under restricted conditions (25 mM Mg(2+)), the substrate specificity of Biota orientalis RNase is extremely high: it acts only on the "Biota orientalis RNase region" of the largest RNA in ribosomes from certain eukaryotes. The ribosome specifically damaged by Biota orientalis RNase is unable to EF-1alpha-dependently bind aminoacyl-tRNA, whereas the formation of the EF-2/GDP/ribosome complex is not affected. It is proposed that Biota orientalis RNase inactivates ribosome at least partially by interfering with the EF-1alpha-dependent binding of aminoacyl-tRNA to ribosome. Biota orientalis RNase might be a useful tool in studying the structure/function of ribosome.
Xu
Hong
H
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, PR China.
He
Wen-Jun
WJ
Liu
Wang-Yi
WY
D000818:Animals; D001483:Base Sequence; D002852:Chromatography, Ion Exchange; D017931:DNA Primers; D018076:DNA, Complementary; D004952:Esters; D006868:Hydrolysis; D051379:Mice; D012339:RNA, Ribosomal, 28S / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism*; D029783:Thuja / Q000201:enzymology
D017931:DNA Primers; D018076:DNA, Complementary; D004952:Esters; D012339:RNA, Ribosomal, 28S; D012260:Ribonucleases