EC 220.127.116.11 Enzyme
purine specific endoribonuclease;
Trichoderma koningi RNase III;
Phosphorus-oxygen lyases (only sub-subclass identified to date)
[RNA]-purine 5'-hydroxy-ribonucleotide-3'-[RNA fragment]-lyase (cyclicizing; [RNA fragment]-3'-purine-nucleoside -2',3'-cyclophosphate-forming and hydrolysing)
(1) [RNA] containing adenosine + H2O = an [RNA fragment]-3'-adenosine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment] (overall reaction);
(1a) [RNA] containing adenosine = an [RNA fragment]-3'-adenosine-2',3'-cyclophosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment];
(1b) an [RNA fragment]-3'-adenosine-2',3'-cyclophosphate + H2O = an [RNA fragment]-3'-adenosine -3'-phosphate;
(2) [RNA] containing guanosine + H2O = an [RNA fragment]-3'-guanosine-3'-phosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment] (overall reaction);
(2a) [RNA] containing guanosine = an [RNA fragment]-3'-guanosine-2',3'-cyclophosphate + a 5'-hydroxy-ribonucleotide-3'-[RNA fragment];
(2b) an [RNA fragment]-3'-guanosine-2',3'-cyclophosphate + H2O = an [RNA fragment]-3'- guanosine-3'-phosphate
[RNA] containing adenosine;
[RNA] containing guanosine;
[RNA fragment]-3'-adenosine -3'-phosphate;
[RNA fragment]-3'- guanosine-3'-phosphate
The enzyme secreted by the fungus Ustilago sphaerogena cleaves at the 3'-phosphate group of purines, and catalyses a two-stage endonucleolytic cleavage. The first reaction produces 5'-hydroxy-phosphooligonucletides and 3'-phosphooligonucleotides ending in Ap or Gp with 2',3'-cyclic phosphodiester, which are released from the enzyme. The enzyme then hydrolyses these cyclic compounds in a second reaction that takes place only when all the susceptible 3',5'-phosphodiester bonds have been cyclised. The second reaction is a reversal of the first reaction using the hydroxyl group of water instead of the 5'-hydroxyl group of ribose. The overall process is that of a phosphorus-oxygen lyase followed by hydrolysis to form the 3'-nucleotides.
EC 18.104.22.168 created 1978 as 22.214.171.124, modified 1981, transferred 2018 to EC 126.96.36.199
GLITZ DG, DEKKER CA.
STUDIES ON A RIBONUCLEASE FROM USTILAGO SPHAEROGENA. I. PURIFICATION AND PROPERTIES OF THE ENZYME.
Biochemistry 3:1391-9 (1964)
GLITZ DG, DEKKER CA.
STUDIES ON A RIBONUCLEASE FROMUSTILAGO SPHAEROGENNA. II. SPECIFICITY OF THE ENZYME.
Biochemistry 3:1399-406 (1964)
Uchida, T. and Egami, F. Microbial ribonucleases with special reference to RNases T1, T 2, N
1, and U2.
In: Boyer, P.D. (Ed.), The Enzymes, 3rd ed., vol. 4, Academic Press, New York, 1971, p. 205-250.
Martinez-Ruiz A, Garcia-Ortega L, Kao R, Onaderra M, Mancheno JM, Davies J, Martinez del Pozo A, Gavilanes JG
Ribonuclease U2: cloning, production in Pichia pastoris and affinity chromatography purification of the active recombinant protein.
FEMS Microbiol Lett 189:165-9 (2000)
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