Polynucleotide:adenosine glycosidase activity of ribosome-inactivating proteins: effect on DNA, RNA and poly(A).
Ribosome-inactivating proteins (RIP) are a family of plant enzymes for which a unique activity was determined: rRNAN-glycosidase at a specific universally conserved position, A4324in the case of rat ribosomes. Recently we have shown that the RIP from Saponaria officinalis have a much wider substrate specificity: they are actually polynucleotide:adenosine glycosidases. Here we extend studies on substrate specificity to most known RIP: 52 purified proteins, both type 1 (single-chain) and type 2 (two chain, an enzymatic chain and a lectin chain) were examined for adenine release on various substrates including RNAs from different sources, DNA, and poly(A). All RIP depurinated extensively DNA and some released adenine from all adenine-containing polynucleotides tested. From experimental evidence the entire class of plant proteins, up to now called ribosome-inactivating proteins, may be classified as polynucleotide:adenosine glycosidases. The newly identified substrates may be implicated in the biological role(s) of RIP.
Barbieri
L
L
Dipartimento di Patologia sperimentale dell'Università degli Studi di Bologna Via San Giacomo 14, I-40126 Bologna, Italy. barbieri@alma.unibo.it
Valbonesi
P
P
Bonora
E
E
Gorini
P
P
Bolognesi
A
A
Stirpe
F
F
D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D004247:DNA / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D000922:Immunotoxins; D008297:Male; D009699:N-Glycosyl Hydrolases; D010940:Plant Proteins / Q000378:metabolism*; D011061:Poly A / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D054789:Ribosome Inactivating Proteins, Type 1; D012270:Ribosomes; D000076985:Saporins; D013094:Spermatozoa; D013379:Substrate Specificity
D000922:Immunotoxins; D010940:Plant Proteins; D012329:RNA, Bacterial; D012367:RNA, Viral; D054789:Ribosome Inactivating Proteins, Type 1; D011061:Poly A; D012313:RNA; D004247:DNA; D003851:Deoxyribonucleases; D012260:Ribonucleases; D006026:Glycoside Hydrolases; D009699:N-Glycosyl Hydrolases; D000076985:Saporins; D000241:Adenosine