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KMID : 0364820080440020093
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Korean Journal of Microbiology
2008 Volume.44 No. 2 p.93 ~ p.97
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Modulation of Escherichia coli RNase E Action by RraAS2, a Streptomyces coelicolor Ortholog of RraA
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Ahn Sang-Mi
Lee Kang-Seok
Shin Eun-Kyoung
Yeom Ji-Hyun
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Abstract
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RraA is a recently discovered protein inhibitor that regulates the enzymatic activity of RNase E, which plays a
major role in the decay and processing of RNAs in Escherichia coli. It has also been shown to regulate the activity
of RNase ES, a functional Streptomyces coelicolor ortholog of RNase E, which has 36% identity to the
amino-terminal region of RNase E. There are two open reading frames in S. coelicolor genome that can potentially
encode proteins having more than 35.4% similarity to the amino acid sequence of RraA. DNA fragment
encoding one of these RraA orthologs, designated as RraAS2 here, was amplified and cloned in to E. coli vector
to test whether it has ability to regulate RNase E activity in E. coli cells. Co-expression of RraAS2 partially rescued
E. coli cells over-producing RNase E from growth arrest, although not as efficiently as RraA, induced by
the increased ribonucleolytic activity in the cells. The copy number of ColE1-type plasmid in these cells was
also decreased by 14% compared to that in cells over-producing RNase E only, indicating the ability of RraAS2
to inhibit RNase E action on RNA I. We observed that the expression level of RraAS2 was lower than that of
RraA by 4.2 folds under the same culture condition, suggesting that because of inefficient expression of RraAS2
in E. coli cells, co-expression of RraAS2 was not efficiently able to inhibit RNase E activity to the level for
proper processing and decay of all RNA species that is required to restore normal cellular growth to the cells
over-producing RNase E.
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KEYWORD
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ColE1-type plasmid, RraA, RraAS2, RNase E, RNase ES
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