Location of the RNA-processing enzymes RNase III, RNase E and RNase P in the Escherichia coli cell.
Cells overexpressing the RNA-processing enzymes RNase III, RNase E and RNase P were fractionated into membrane and cytoplasm. The RNA-processing enzymes were associated with the membrane fraction. The membrane was further separated to inner and outer membrane and the three RNA-processing enzymes were found in the inner membrane fraction. By assaying for these enzymatic activities we showed that even in a normal wild-type strain of Escherichia coli these enzymes fractionate primarily with the membrane. The RNA part of RNase P is found in the cytosolic fraction of cells overexpressing this RNA, while the overexpressed RNase P protein sediments with the membrane fraction; this suggests that the RNase P protein anchors the RNA catalytic moiety of the enzyme to a larger entity. The implications of these findings for the cellular organization of the RNA-processing enzymes in the cell are discussed.
Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri 63110.
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Miczak
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Srivastava
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Apirion
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry; D002458:Cell Fractionation; D003593:Cytoplasm / Q000737:chemistry; D004722:Endoribonucleases / Q000032:analysis*; D004926:Escherichia coli / Q000201:enzymology* / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D008566:Membranes / Q000737:chemistry; D012323:RNA Processing, Post-Transcriptional; D016337:RNA, Catalytic / Q000032:analysis*; D043244:Ribonuclease III; D043262:Ribonuclease P
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D016337:RNA, Catalytic; D004722:Endoribonucleases; D043244:Ribonuclease III; C468366:ribonuclease III, E coli; D043262:Ribonuclease P; C470865:ribonuclease P, E coli; C022537:ribonuclease E