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Decay of the IS 10 antisense RNA by 3′ exoribonucleases: evidence that RNase II stabilizes RNA‐OUT against PNPase attack
Author(s) -
Pepe Cynthia M.,
MaslešaGalić Saša,
Simons Robert W.
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb00504.x
Subject(s) - polynucleotide phosphorylase , biology , rnase p , rna , exoribonuclease , exosome complex , rnase ph , degradosome , rnase h , non coding rna , ribonuclease , antisense rna , microbiology and biotechnology , genetics , purine nucleoside phosphorylase , biochemistry , gene , enzyme , purine
Summary RNA‐OUT, the 69‐nucleotide antisense RNA that regulates Tn 10 /IS 10 transposition folds into a simple stem‐loop structure. The unusually high metabolic stability of RNA‐OUT is dependent, in part, on the integrity of its stem‐domain: mutations that disrupt stem‐domain structure (Class II mutations) render RNA‐OUT unstable, and restoration of structure restores stability. Indeed, there is a strong correlation between the thermodynamic and metabolic stabilities of RNA‐OUT. We show here that stem‐domain integrity determines RNA‐OUT's resistance to 3’exoribonucleolytic attack: Class II mutations are almost completely suppressed in Escherichia coli cells lacking its principal 3′ exoribonucleases, ribonuclease II (RNase II) and polynucleotide phosphorylase (PNPase). RNase II and PNPase are individually able to degrade various RNA‐OUT species, albeit with different efficiencies: RNA‐OUT secondary structure provides greater resistance to RNase II than to PNPase. Surprisingly, RNA‐OUT is threefold more stable in wild‐type cells than in cells deficient for RNase II activity, suggesting that RNase II somehow lessens RNPase attack on RNA‐OUT. We discuss how this might occur. We also show that wild‐type RNA‐OUT stability changes only twofold across the normal range of physiological growth temperatures (30–44°C) in wild‐type cells, which has important implications for IS 10 biology.