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Title: Membrane Recognition and Dynamics of the RNA Degradosome
Authors: Strahl H.
Turlan C.
Khalid S.
Bond P.J. 
Kebalo J.-M.
Peyron P.
Poljak L.
Bouvier M.
Hamoen L.
Luisi B.F.
Carpousis A.J.
Keywords: DEAD box protein
DEAD box RNA helicase RhlB
ribonuclease E
RNA degradosome
unclassified drug
DEAD box protein
Escherichia coli protein
messenger RNA
multienzyme complex
polyribonucleotide nucleotidyltransferase
RhlB protein, E coli
ribonuclease E
RNA helicase
alpha helix
cell membrane
controlled study
enzyme substrate
Escherichia coli
inner membrane
membrane targeting sequence
molecular dynamics
molecular recognition
phospholipid bilayer
protein protein interaction
RNA degradation
membrane structure
molecular dynamics
RNA stability
Cell Membrane Structures
DEAD-box RNA Helicases
Escherichia coli
Escherichia coli Proteins
Molecular Dynamics Simulation
Multienzyme Complexes
Nucleic Acid Conformation
Polyribonucleotide Nucleotidyltransferase
Protein Interaction Maps
RNA Helicases
RNA Stability
RNA, Messenger
Issue Date: 2015
Citation: Strahl H., Turlan C., Khalid S., Bond P.J., Kebalo J.-M., Peyron P., Poljak L., Bouvier M., Hamoen L., Luisi B.F., Carpousis A.J. (2015). Membrane Recognition and Dynamics of the RNA Degradosome. PLoS Genetics 11 (2) : 1-23. ScholarBank@NUS Repository.
Rights: Attribution 4.0 International
Abstract: RNase E, which is the central component of the multienzyme RNA degradosome, serves as a scaffold for interaction with other enzymes involved in mRNA degradation including the DEAD-box RNA helicase RhlB. Epifluorescence microscopy under live cell conditions shows that RNase E and RhlB are membrane associated, but neither protein forms cytoskeletal-like structures as reported earlier by Taghbalout and Rothfield. We show that association of RhlB with the membrane depends on a direct protein interaction with RNase E, which is anchored to the inner cytoplasmic membrane through an MTS (Membrane Targeting Sequence). Molecular dynamics simulations show that the MTS interacts with the phospholipid bilayer by forming a stabilized amphipathic �-helix with the helical axis oriented parallel to the plane of the bilayer and hydrophobic side chains buried deep in the acyl core of the membrane. Based on the molecular dynamics simulations, we propose that the MTS freely diffuses in the membrane by a novel mechanism in which a large number of weak contacts are rapidly broken and reformed. TIRFm (Total Internal Reflection microscopy) shows that RNase E in live cells rapidly diffuses over the entire inner membrane forming short-lived foci. Diffusion could be part of a scanning mechanism facilitating substrate recognition and cooperativity. Remarkably, RNase E foci disappear and the rate of RNase E diffusion increases with rifampicin treatment. Control experiments show that the effect of rifampicin is specific to RNase E and that the effect is not a secondary consequence of the shut off of E. coli transcription. We therefore interpret the effect of rifampicin as being due to the depletion of RNA substrates for degradation. We propose a model in which formation of foci and constraints on diffusion arise from the transient clustering of RNase E into cooperative degradation bodies. ? 2015 Strahl et al.
Source Title: PLoS Genetics
ISSN: 15537390
DOI: 10.1371/journal.pgen.1004961
Rights: Attribution 4.0 International
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