Unraveling new roles for minor components of the E. coli RNA degradosome

Endoribonuclease E, 3'-5' exoribonuclease polynucleotide phosphorylase, RhIB RNA helicase and enolase form a multienzyme complex (the "degradosome") playing an important role in RNA processing and decay in Escherichia coli. Although a number of proteins that occasionally co-purify with the E. coli degradosome in non-stoichiometric amounts were initially viewed as insignificant constituents of this complex, recent studies suggest that, in fact, some of these copurifying proteins are involved in modulation of degradosome composition, activity or specificity during bacterial adaptation to changing environments. Here we briefly review these findings and discuss their implications for understanding the multifaceted mechanisms controlling degradosome functions in vivo.