Ssu-Jean Chang^a, Shih-Yang Hsieh^b, Hanna S. Yuana^b and Kin-Fu Chak^a

^a Institute of Biochemistry, National Yang Ming University, Shih-Pai, Taipei 11221, Taiwan, ROC

^b Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan, ROC

Abstract

Posttranscriptional control of the bactericidal ColE7 operon has been implicated by a feedback endonucleolytic cleavage of its own mRNA. The cleavage site has been located at the coding region of ceiE7, the second cistron of the ColE7 cea–cei–cel polycistronic transcript. Interestingly, Im7 protein, the translation product of ceiE7, is required for the specific cleavage. It was found that both sequence (GAUCUGAUU) flanking the cleavage site and the putative T1 stem-loop structure distal to the coding region of ceiE7 gene play a critical role for the specific cleavage of ceiE7-mRNA. Furthermore, we have verified that a di-nucleotide GG sequence located at the topmost position of the loop region of the putative stem-loop structure is essential for the specific cleavage of ceiE7-mRNA. Thus, our data reveal the existence of a novel mRNA degradative machinery for the regulation of the expression of ColE7 operon.

Author Keywords: Colicin E7; mRNA decay; Specific cleavage of mRNA; Stem-loop structure of RNA

Biochem. and Biophys. Res. Commun.  299, 613-620 (2002)