Point mutations distal to the processing site affect Drosophila pre-5 S RNA processing. Long range cooperation and a breathing model.
Drosophila pre-5 S RNA, which consists of five conserved stem-loop domains and a 15-nucleotide 3' tail, is 3'-end processed to 120 nucleotide mature 5 S RNA before ribosome assembly. Large deletions in stems II and III, all of stems IV and V, and loop C prohibit Drosophila 5 S RNA processing; deletion of stem IV and half of V does not (Preiser, P. R., and Levinger, L. (1991a) J. Biol. Chem. 266, 7509-7516). Several point mutations in stem I reduce, while certain neighboring sequence changes stimulate, processing (Levinger, L., Vasisht, V., Greene, V., and Arjun, I. (1992) J. Biol. Chem. 267, 23683-23687). Herein we extend this 5 S RNA fine structure analysis to regions farther from the processing site. Most point mutations in loop B, stem III, and loop C severely inhibit processing. One loop C substitution stimulates processing; when combined with stimulatory sequence changes in stem I and loop A, these dispersed mutations improve processing manyfold, perhaps by stabilizing a required conformation or strengthening a protein-binding site. Central stem II sequence changes inhibit processing; several adjacent sequence substitutions which weaken base pairing improve processing. Combining these results with earlier work from stem I and loop A, we hypothesize that slight reduction in base pairing may improve groove access of polypeptide chains to essential contact positions.
York College of the City University of New York, Jamaica 11451.
V
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Vasisht
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Greene
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Arjun
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Levinger
D000818:Animals; D001483:Base Sequence; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012341:RNA, Ribosomal, 5S / Q000096:biosynthesis* / Q000737:chemistry; D017384:Sequence Deletion
D012322:RNA Precursors; D012341:RNA, Ribosomal, 5S