Isolation and characterization of a U-specific 3'-5'-exonuclease from mitochondria of Leishmania tarentolae.
We have purified a 3'-5'-exoribonuclease from mitochondrial extract of Leishmania tarentolae over 4000-fold through six column fractionations. This enzyme digested RNA in a distributive manner, showed a high level of specificity for 3'-terminal Us, and was blocked by a terminal dU; there was slight exonucleolytic activity on a 3'-terminal A or C but no activity on a 3'-terminal G residue. The enzyme preferred single-stranded 3'-oligo(U) overhangs and did not digest duplex RNA. Two other 3'-5'-exoribonuclease activities were also detected in the mitochondrial extract, one of which was stimulated by a 3'-phosphate and the other of which degraded RNAs with a 3'-OH to mononucleotides in a processive manner. The properties of the distributive U-specific 3'-5'-exoribonuclease suggest an involvement in the U-deletion RNA editing reaction that occurs in the mitochondrion of these cells.
Department of Microbiology, Howard Hughes Medical Institute, University of California, Los Angeles, California 90095, USA.
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Aphasizhev
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Simpson
D000818:Animals; D001483:Base Sequence; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000302:isolation & purification* / Q000378:metabolism*; D007700:Kinetics; D007891:Leishmania / Q000201:enzymology*; D008928:Mitochondria / Q000201:enzymology*; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D014498:Uracil
D014498:Uracil; D012313:RNA; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V