Figure 3.

Bacterial mRNA decay machineries. (A) The RNA degradosome is a multicomponent ribonucleolytic complex that includes an endoribonuclease (RNase E), a 3'→5' exoribonuclease (polynucleotide phosphorylase (PNPase)), a DEAD-box RNA helicase (RhlB helicase), and the glycolytic enzyme enolase [31-33]). (B) In E. coli, PNPase is associated with the RhlB independently of the RNA degradosome to form an evolutionarily conserved RNA-degradation machine termed as the "bacterial exosome" [34,35]. This complex was shown to catalyze the 3'→ 5' exonucleolytic degradation of RNA using RhlB as cofactor to unwind structured RNA in an ATP-dependent manner.