Abstract
RNase M, an enzyme previously purified to homogeneity from Escherichia coli, was suggested to be the RNase responsible for mRNA degradation in this bacterium. Although related to the endoribonuclease, RNase I, its distinct properties led to the conclusion that RNase M was a second, low molecular mass, broad specificity endoribonuclease present in E. coli. However, based on sequence analysis, southern hybridization, and enzyme activity, we show that RNase M is, in fact, a multiply altered form of RNase I. In addition to three amino acid substitutions that confer the properties of RNase M on the mutated RNase I, the protein is synthesized from an rna gene that contains a UGA nonsense codon at position 5, apparently as a result of a low level of readthrough. We also suggest that RNase M is just one of several previously described endoribonuclease activities that are actually manifestations of RNase I.
Full Text
The Full Text of this article is available as a PDF (359.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1006/abio.1976.9999. [DOI] [PubMed] [Google Scholar]
- Cannistraro V. J., Kennell D. Purification and characterization of ribonuclease M and mRNA degradation in Escherichia coli. Eur J Biochem. 1989 May 1;181(2):363–370. doi: 10.1111/j.1432-1033.1989.tb14733.x. [DOI] [PubMed] [Google Scholar]
- Datta A. K., Burma D. P. Association of ribonuclease I with ribosomes and their subunits. J Biol Chem. 1972 Nov 10;247(21):6795–6801. [PubMed] [Google Scholar]
- Deutscher M. P., Hilderman R. H. Isolation and partial characterization of Escherichia coli mutants with low levels of transfer ribonucleic acid nucleotidyltransferase. J Bacteriol. 1974 May;118(2):621–627. doi: 10.1128/jb.118.2.621-627.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gurevitz M., Watson N., Apirion D. A cleavage site of ribonuclease F. A putative processing endoribonuclease from Escherichia coli. Eur J Biochem. 1982 Jun;124(3):553–559. [PubMed] [Google Scholar]
- Meador J., 3rd, Cannon B., Cannistraro V. J., Kennell D. Purification and characterization of Escherichia coli RNase I. Comparisons with RNase M. Eur J Biochem. 1990 Feb 14;187(3):549–553. doi: 10.1111/j.1432-1033.1990.tb15336.x. [DOI] [PubMed] [Google Scholar]
- NEU H. C., HEPPEL L. A. THE RELEASE OF RIBONUCLEASE INTO THE MEDIUM WHEN ESCHERICHIA COLI CELLS ARE CONVERTED TO SPEROPLASTS. J Biol Chem. 1964 Nov;239:3893–3900. [PubMed] [Google Scholar]
- Parker J. Errors and alternatives in reading the universal genetic code. Microbiol Rev. 1989 Sep;53(3):273–298. doi: 10.1128/mr.53.3.273-298.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spahr P. F., Gesteland R. F. Specific cleavage of bacteriophage R17 RNA by an endonuclease isolated from E. coli MRE-600. Proc Natl Acad Sci U S A. 1968 Mar;59(3):876–883. doi: 10.1073/pnas.59.3.876. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wade H. E., Robinson H. K. Magnesium ion-independent ribonucleic acid depolymerases in bacteria. Biochem J. 1966 Nov;101(2):467–479. doi: 10.1042/bj1010467. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhu L. Q., Gangopadhyay T., Padmanabha K. P., Deutscher M. P. Escherichia coli rna gene encoding RNase I: cloning, overexpression, subcellular distribution of the enzyme, and use of an rna deletion to identify additional RNases. J Bacteriol. 1990 Jun;172(6):3146–3151. doi: 10.1128/jb.172.6.3146-3151.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhu L., Deutscher M. P. The Escherichia coli rna gene encoding RNase I: sequence and unusual promoter structure. Gene. 1992 Sep 21;119(1):101–106. doi: 10.1016/0378-1119(92)90072-w. [DOI] [PubMed] [Google Scholar]