Escherichia coli endoribonuclease RNase E: autoregulation of expression and site-specific cleavage of mRNA |
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Authors: | Elisabeth A Mudd Christopher F Higgins |
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Institution: | Imperial Cancer Research Fund Laboratories, Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford 0X3 9DU, UK |
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Abstract: | Mutations in the Escherichia coli rne (ams) gene have a general effect on the rate of mRNA decay in vivo. Using antibodies we have shown that the product of the rne gene is a polypeptide of relative mobility 180kDa. However, proteolytic fragments as small as 70kDa, which can arise during purification, also exhibit RNase E activity, in vitro studies demonstrate that the rne gene product, RNase E, is an endoribonuclease that cleaves mRNA at specific sites. RNase E cleaves rne mRNA and autoregulates the expression of the rne gene. In addition we demonstrate RNase E-dependent endonucleolytic cleavage of ompA mRNA, at a site known to be rate-determining for degradation and reported to be cieaved by RNase K. Our data are consistent with RNase K being a proteolytic fragment of RNase E. |
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