THE N-TERMINAL DOMAIN OF THE RNE GENE-PRODUCT HAS RNASE-E ACTIVITY AND IS NONOVERLAPPING WITH THE ARGININE-RICH RNA-BINDING SITE

The rne gene of Escherichia coli encodes a 118 kDa protein that has ri bonuclease E (RNase E) activity and binds RNA. A functional I ne gene product is essential for cell viability and for the processing and/or decay of a variety of RNA species, including 9 S RNA, mRNA and RNAI, t he antisense RNA regulator of ColE1-type plasmid replication. By testi ng the ability of different segments of the Rne protein to catalyze RN A cleavage and to bind RNA, we found that the N-terminal half (residue s 1 to 498) of Rne contains a catalytic function sufficient for site-s pecific cleavage of oligoribonucleotides and complex RNAs. The C-termi nal half of the protein, which contains both an arginine-rich region ( residues 597 to 684) that we show binds RNA and a segment that is esse ntial for cell viability (residues 844 to 1061), had no detectable end oribonucleolytic activity Our results, which map the catalytic domain of RNase E, indicate the existence of discrete functional domains with in the multifaceted Rne protein. (C) 1996 Academic Press Limited