The 3'-ends of both prokaryotic and eukaryotic mRNA are polyadenylated, but the 
poly(A) tracts of prokaryotic mRNA are generally shorter, ranging from 15 to 60 
adenylate residues and associated with only 2-60% of the molecules of a given 
mRNA species. The sites of polyadenylation of bacterial mRNA are diverse and 
include the 3'-ends of primary transcripts, the sites of endonucleolytic 
processing in the 3' untranslated and intercistronic regions, and sites within 
the coding regions of mRNA degradation products. The diversity of 
polyadenylation sites suggests that mRNA polyadenylation in prokaryotes is a 
relatively indiscriminate process that can occur at all mRNA's 3'-ends and does 
not require specific consensus sequences as in eukaryotes. Two poly(A) 
polymerases have been identified in Escherichia coli. They are encoded by 
unlinked genes, neither of which is essential for growth, suggesting significant 
functional overlap. Polyadenylation promotes the degradation of a regulatory RNA 
that inhibits the replication of bacterial plasmids and may play a similar role 
in the degradation of mRNA. However, under certain conditions, poly(A) tracts 
may lead to mRNA stabilization. Their ability to bind S1 ribosomal protein 
suggests that poly(A) tracts may also play a role in mRNA translation.