title: Non-specific deadenylation and deguanylation of naked RNA catalyzed by ricin under acidic condition.
abstract: Ricin A-chain catalyzes the hydrolysis of the N-glycosidic bond of a conserved adenosine residue at position 4324 in the sarcin/ricin domain of 28S RNA of rat ribosome. The GAGA tetraloop closed by C-G pairs is required for recognition of the cleavage site on 28S ribosomal RNA by ricin A-chain. In this study, ricin A-chain (reduced ricin) exhibits specific depurination on a synthetic oligoribonucleotide (named SRD RNA) mimic of the sarcin/ricin domain of rat 28S ribosomal RNA under neutral and weak acidic conditions. Furthermore, the activity of intact ricin is also similar to that of ricin A-chain. However, under more acidic conditions, both enzymes lose their site specificity. The alteration in specificity of depurination is not dependent on the GAGA tetraloop of SRD RNA. A higher concentration of KCl inhibits the non-specific N-glycosidase activity much more than the specific activity of ricin A-chain. In addition, characterization of depurination sites by RNA sequencing reveals that under acidic conditions ricin A-chain can release not only adenines, but also guanines from SRD RNA or 5S ribosomal RNA. This is the first report of the non-specific deadenylation and deguanylation activity of ricin A-chain to the naked RNA under acidic conditions.
authors: Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-yang Road, 200031, Shanghai, PR China.
authors: S
authors: S
authors: Tang
authors: L
authors: L
authors: Xie
authors: F
authors: F
authors: Hou
authors: W Y
authors: WY
authors: Liu
authors: K
authors: K
authors: Ruan
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002384:Catalysis; D006157:Guanosine Monophosphate / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011189:Potassium Chloride / Q000494:pharmacology; D012341:RNA, Ribosomal, 5S / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D012276:Ricin / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D012341:RNA, Ribosomal, 5S; D000249:Adenosine Monophosphate; D011189:Potassium Chloride; D006157:Guanosine Monophosphate; D012276:Ricin