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Isolation and characterization of an NTP-dependent 3'-exoribonuclease from mitochondria of Saccharomyces cerevisiae.

1993; Elsevier BV; Volume: 268; Issue: 10 Linguagem: Inglês

10.1016/s0021-9258(18)53182-3

1083-351X

Jinrong Min, Rita M. Heuertz, Hans Peter Zassenhaus,

Enzyme Structure and Function

Abstract RNA turnover in eukaryotes is thought to require 3'-exonuclease activity but so far no RNase with that specificity has been isolated from a eukaryote. We report here on the purification and characterization of a 3'-exoribonuclease isolated from the mitochondria of Saccharomyces cerevisiae. In vitro the purified enzyme displayed an absolute requirement of NTPs for activity. Each of the eight standard ribo- and deoxyribonucleotides supported activity with Km values ranging from 20 to 90 microM. The enzyme also displayed RNA-stimulated NTPase activity. The NTP-dependent enzyme cofractionated with three polypeptides of molecular masses 75,000, 90,000, and 110,000 daltons, although the native enzyme appears to have a molecular mass of 160,000 daltons predicted from the Stokes radius. The possible functions of this enzyme in vivo in the regulated decay of mitochondrial RNAs are discussed.