TY - JOUR
T1 - RNase PH
T2 - an Escherichia coli phosphate-dependent nuclease distinct from polynucleotide phosphorylase.
AU - Deutscher, M. P.
AU - Marshall, G. T.
AU - Cudny, H.
PY - 1988/7
Y1 - 1988/7
N2 - Final trimming of the 3' terminus of tRNA precursors in Escherichia coli is thought to proceed by an exonucleolytic mechanism. However, mutant strains lacking as many as four exoribonucleases known to act on tRNA still grow normally and process tRNA normally. Extracts from such a multiple-RNase-deficient strain accurately mature tRNA precursors exonucleolytically in vitro in a reaction that requires inorganic phosphate. Here we show that this reaction is not due to polynucleotide phosphorylase (PNPase) but, rather, that it is mediated by a phosphate-requiring exonuclease that we have named RNase PH. Purified PNPase is incapable of completely processing tRNA precursors, and extracts from a PNPase- strain retain full activity for phosphorolytic processing. Although both PNPase and RNase PH act in a phosphorolytic manner, they differ substantially in size and substrate specificity. RNase PH has a molecular mass of 45-50 kDa and favors tRNA precursors as substrates. The possible physiological role of RNase PH and the advantages of phosphorolytic processing are discussed.
AB - Final trimming of the 3' terminus of tRNA precursors in Escherichia coli is thought to proceed by an exonucleolytic mechanism. However, mutant strains lacking as many as four exoribonucleases known to act on tRNA still grow normally and process tRNA normally. Extracts from such a multiple-RNase-deficient strain accurately mature tRNA precursors exonucleolytically in vitro in a reaction that requires inorganic phosphate. Here we show that this reaction is not due to polynucleotide phosphorylase (PNPase) but, rather, that it is mediated by a phosphate-requiring exonuclease that we have named RNase PH. Purified PNPase is incapable of completely processing tRNA precursors, and extracts from a PNPase- strain retain full activity for phosphorolytic processing. Although both PNPase and RNase PH act in a phosphorolytic manner, they differ substantially in size and substrate specificity. RNase PH has a molecular mass of 45-50 kDa and favors tRNA precursors as substrates. The possible physiological role of RNase PH and the advantages of phosphorolytic processing are discussed.
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U2 - 10.1073/pnas.85.13.4710
DO - 10.1073/pnas.85.13.4710
M3 - Article
C2 - 2455297
AN - SCOPUS:0024042164
VL - 85
SP - 4710
EP - 4714
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 13
ER -