RNase E is an essential enzyme in Escherichia coli. The cleavage site of this single-stranded specific endoribonuclease is
well-characterized in many RNA substrates. Here, we report that the upregulation of RNase E cleavage activity by a mutation
that affects either RNA binding (Q36R) or enzyme multimerization (E429G) was accompanied by relaxed cleavage specificity.
Both mutations led to enhanced RNase E cleavage in RNA I, an antisense RNA of ColE1-type plasmid replication,
at a major site and other cryptic sites. Expression of a truncated RNA I with a major RNase E cleavage site deletion at the
5′-end (RNA I-
5) resulted in an approximately twofold increase in the steady-state levels of RNA I-
5 and the copy number
of ColE1-type plasmid in E. coli cells expressing wild-type or variant RNase E compared to those expressing RNA I. These results indicate that RNA I-
5 does not efficiently function as an antisense RNA despite having a triphosphate group at the
5′-end, which protects the RNA from ribonuclease attack. Our study suggests that increased cleavage rates of RNase E lead
to relaxed cleavage specificity on RNA I and the inability of the cleavage product of RNA I as an antisense regulator in vivo
does not stem from its instability by having 5′-monophosphorylated end.
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Engineering an Escherichia coli based in vivo mRNA manufacturing platform Edward Curry, George Muir, Jixin Qu, Zoltán Kis, Martyn Hulley, Adam Brown Biotechnology and Bioengineering.2024; 121(6): 1912. CrossRef