The cytotoxin α-sarcin behaves as a cyclizing ribonuclease

• Published in: FEBS letters 1998-03, Vol.424 (1), p.46-48
• Main Authors: Lacadena, Javier, Martı́nez del Pozo, Alvaro, Lacadena, Valle, Martı́nez-Ruiz, Antonio, Mancheño, José M, Oñaderra, Mercedes, Gavilanes, José G
• Format: Article
• Language: English
• Subjects: 2′(3′)-AMP, adenosine 2′- and 3′-monophosphate (mixed isomers); 2′,3′-cAMP, adenosine 2′,3′ cyclic monophosphate; 2′,3′-cGMP, guanosine 2′,3′ cyclic monophosphate; 2′-AMP, adenosine 2′-monophosphate; 3′-AMP, adenosine 3′-monophosphate; 3′-GMP, guanosine 3′-monophosphate; ApA, adenylyl(3′→5′)adenosine; Aspergillus - metabolism; Chromatography, High Pressure Liquid; Dinucleotide; Endoribonucleases - isolation & purification; Endoribonucleases - metabolism; Fungal Proteins; GpA, guanylyl(3′→5′)adenosine; Hydrolysis; Oligoribonucleotides - metabolism; poly(A), polyadenylic acid; Ribonucleases - metabolism; Ribonucleolytic activity; Ribosome-inactivating protein; Ribotoxin; RNase A, bovine pancreatic ribonuclease A; RNase T1, ribonuclease T1 from Aspergillus oryzae
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(98)00137-9

The hydrolysis of adenylyl(3′→5′)adenosine (ApA) and guanylyl(3′→5′)adenosine (GpA) dinucleotides by the cytotoxic protein α-sarcin has been studied. Quantitative analysis of the reaction has been performed through reverse-phase chromatographic (HPLC) separation of the resulting products. The hydrolysis of the 3′-5′ phosphodiester bond of these substrates yields the 2′-3′ cyclic mononucleotide; this intermediate is converted into the corresponding 3′-monophosphate derivative as the final product of the reaction. The values of the apparent Michaelis constant ( K M), k cat and k cat/ K M have also been calculated. The obtained results fit into a two-step mechanism for the enzymatic activity of α-sarcin and allow to consider this protein as a cyclizing RNase.