| Title | RraAS2 requires both scaffold domains of RNase ES for high-affinity binding and inhibitory action on the ribonucleolytic activity |
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| Author | Jihune Heo1, Daeyoung Kim1, Minju Joo1, Boeun Lee1, Sojin Seo1, Jaejin Lee1, Saemee Song2, Ji-Hyun Yeom1, Nam-Chul Ha2, and Kangseok Lee1* |
| Address | 1Department of Life Science, Chung-Ang University, Seoul 06974, Republic of Korea, 2Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea |
| Bibliography | Journal of Microbiology, 54(10),660-666, 2016, |
| DOI | 10.1007/s12275-016-6417-9 |
| Key Words | Streptomyces coelicolor, RNA stability, RNase ES, RraAS2 |
| Abstract | RraA is a protein inhibitor of RNase E (Rne), which catalyzes the endoribonucleolytic cleavage of a large proportion of RNAs in Escherichia coli. The antibiotic‐producing bacterium Streptomyces coelicolor also contains homologs of RNase E and RraA, designated as RNase ES (Rns), RraAS1, and RraAS2, respectively. Here, we report that RraAS2 requires both scaffold domains of RNase ES for high-affinity binding and inhibitory action on the ribonucleolytic activity. Analyses of the steady-state level of RNase E substrates indicated that coexpression of RraAS2 in E. coli cells overproducing Rns effectively inhibits the ribonucleolytic activity of full-length RNase ES, but its inhibitory effects were moderate or undetectable on other truncated forms of Rns, in which the N- or/and C-terminal scaffold domain was deleted. In addition, RraAS2 more efficiently inhibited the in vitro ribonucleolytic activity of RNase ES than that of a truncated form containing the catalytic domain only. Coimmunoprecipitation and in vivo cross-linking experiments further showed necessity of both scaffold domains of RNase ES for high-affinity binding of RraAS2 to the enzyme, resulting in decreased RNA-binding capacity of RNase ES. Our results indicate that RraAS2 is a protein inhibitor of RNase ES and provide clues to how this inhibitor affects the ribonucleolytic activity of RNase ES. |