Characterization of the E.coli poly(A) polymerase: nucleotide specificity, RNA-binding affinities and RNA structure dependence.

ABSTRACT: Polyadenylation of RNA molecules in bacteria and chloroplasts has been implicated as part of the RNA degradation pathway. The polyadenylation reaction is performed in Escherichia coli mainly by the enzyme poly(A) polymerase I (PAP I). In order to understand the molecular mechanism of RNA poly-adenylation in bacteria, we characterized the biochemical properties of this reaction in vitro using the purified enzyme. Unlike the PAP from yeast nucleus, which is specific for ATP, E.coli PAP I can use all four nucleotide triphosphates as substrates for addition of long ribohomopolymers to RNA. PAP I displays a high binding activity to poly(U), poly(C) and poly(A) ribohomopolymers, but not to poly(G). The 3'-ends of most of the mRNA molecules in bacteria are characterized by a stem-loop structure.

SUBMITTER: Yehudai-Resheff S 

PROVIDER: S-EPMC102612 | biostudies-literature | 2000 Mar

REPOSITORIES: biostudies-literature