<p>The eubacterial degradosome is a large, multi-protein, multi-enzyme complex involved in RNA processing and degradation in <taxon tax_id="562">Escherichia coli</taxon> and other proteobacteria [<cite idref="PUB00033948"/>]. </p><p>The components of the RNA degradosome in E. coli are:</p><p> <ul><li>Ribonuclease E (Rne), <db_xref db="SWISSPROT" dbkey="P21513"/> (<db_xref db="INTERPRO" dbkey="IPR004659"/>)</li><li>ATP-dependent RNA helicase (RhlB), <db_xref db="SWISSPROT" dbkey="P0A8J8"/> (<db_xref db="INTERPRO" dbkey="IPR000629"/>)</li><li>Polynucleotide phosphorylase (Pnp), <db_xref db="SWISSPROT" dbkey="P05055"/> (<db_xref db="INTERPRO" dbkey="IPR012162"/>)</li><li>Enolase (Eno), <db_xref db="SWISSPROT" dbkey="P0A6P9"/> (<db_xref db="INTERPRO" dbkey="IPR000941"/>)</li></ul> </p><p>Associated components:</p><p>The chaperone protein DnaK (<db_xref db="SWISSPROT" dbkey="P0A6Y8"/>, <db_xref db="INTERPRO" dbkey="IPR012725"/>) associates to abnormal complexes in which the canonical components RhlB and PNPase are not present or present in limiting amount and could be involved in repairing such incorrectly assembled degradosomes. Polyphosphate kinase (Ppk), (<db_xref db="SWISSPROT" dbkey="P0A7B1"/>, <db_xref db="INTERPRO" dbkey="IPR003414"/>) appears to maintain an appropriate microenvironment, removing inhibitory polyphosphate and NDPs and regenerating ATP.</p><p>Subunit composition of the E. coli degradosome: [(Ppk)4][(Rne)4][(RhlB)2][(Pnp)3][(Eno)2] (see: http://biocyc.org/ECOLI/NEW-IMAGE?type=POLYPEPTIDE&object=CPLX0-2381). </p><p>In vitro a "minimal" degradosome composed of only RNase E, PNPase and RhlB degrades malEF REP RNA in an ATP-dependent manner in vitro, with activity equivalent to purified whole degradosomes. RNase E enzymatic function is dispensable, whereas PNPase must be catalytically active and incorporated into the degradosome for degradation to occur [<cite idref="PUB00033640"/>]. RNase E provides the organisational structure for the degradosome [<cite idref="PUB00033641"/>]. It is tethered to the cytoplasmic membrane via its amino-terminus [<cite idref="PUB00033642"/>] and its carboxy-terminal half, which is largely unstructured and poorly conserved, coordinates the binding of PNPase, RhlB and enolase. The loss of this portion of the protein prevents degradation of a number of degradosome substrates, including the ptsG and mukB mRNAs and RNA I [<cite idref="PUB00033643"/>, <cite idref="PUB00033644"/>, <cite idref="PUB00033645"/>]. </p><p>Ribonuclease E (<db_xref db="EC" dbkey="3.1.4"/>) is responsible for maturing 5S rRNA from its precursors from all the rRNA genes. It also cleaves RNA I, a molecule that controls the replication of ColE1 plasmid DNA. It is the major endoribonuclease participating in mRNA turnover in E. coli, and initiates decay of RNAs by cutting them internally near their 5'-end. It is able to remove poly A tails by an endonucleolytic process. Ribonuclease G is smaller than RNase E lacking the C-terminal region. It is involved in processing of the 5' end of 16S rRNA, and may be involved in chromosome segregation and cell division too.</p><p>RNase E is a major subunit the eubacterial degradosome. It is a large, multiprotein, multienzyme complex involved in RNA processing and degradation in E. coli and other proteobacteria [<cite idref="PUB00033948"/>]. It consists of the RNA degradation enzymes RNase E (Rne) and PNPase (Pnp), as well as the ATP-dependent RNA helicase (RhlB) and the metabolic enzyme enolase (Eno) [<cite idref="PUB00033637"/>, <cite idref="PUB00033638"/>, <cite idref="PUB00033639"/>].</p>
Ribonuclease E/G