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KMID : 0364820100460020223
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Korean Journal of Microbiology
2010 Volume.46 No. 2 p.223 ~ p.227
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Implications of Growth Arrest Induced by Overproduction of RraB in Escherichia coli
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Ryou Sang-Mi
Yeom Ji-Hyun
Go Ha-Young
Shin Eun-Kyoung
Lee Kang-Seok
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Abstract
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RNase E plays a major role in the degradation and processing of a large number of RNA transcripts in Escherichia coli and forms the core component of the degradosome, a large protein complex involved in RNA metabolism. RraA and RraB are recently discovered protein inhibitors of RNase E and are evolutionarily conserved. In this study, we observed that, unlike RraA, overexpression of RraB did not rescue growth arrest of E. coli cells overexpressing RNase E. To examine whether this phenomenon stems from differential inhibitory effects of RraA and RraB on RNase E substrates, we analyzed three in vivo RNase E substrates. The results showed that RraA inhibited RNase E activity more efficiently than RraB on the degradation of RNA I, which controls the copy number of ColE1- type plasmid, and rpsO mRNA encoding ribosomal protein S15, while RraB was unable to inhibit the processing of pM1 RNA, a precursor of the RNA component of RNase P, by RNase E. Our results imply that RraB inhibits RNase E activity in a more substrate-dependent manner than RraA and this property of RraB may explain why overexpression of RraB could not rescue cells overexpressing RNase E from growth arrest.
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KEYWORD
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degradosome, RNA stability, RNase E, RraA, RraB
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