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Escherichia coli transcription factor NusG binds to 70S ribosomes
Author(s) -
Saxena Shivalika,
Myka Kamila K.,
Washburn Robert,
Costantino Nina,
Court Donald L.,
Gottesman Max E.
Publication year - 2018
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13953
Subject(s) - biology , ribosome , microbiology and biotechnology , transcription (linguistics) , rna polymerase , plasma protein binding , bacterial transcription , translocase , transcription factor , biophysics , polymerase , escherichia coli , biochemistry , dna , rna , gene , linguistics , philosophy , chromosomal translocation
Summary Transcription and translation are coupled processes in bacteria. A role of transcription elongation cofactor NusG in coupling has been suggested by in vitro structural studies. NMR revealed association of the NusG carboxy‐terminal domain with S10 (NusE), implying a direct role for NusG as a bridge linking RNAP and the lead ribosome. Here we present the first in vitro and in vivo evidence of full‐length NusG association with mature 70S ribosomes. Binding did not require accessory factors in vitro . Mutating the NusG:S10 binding interface at NusG F165 or NusE M88 and D97 residues weakened NusG:S10 association in vivo and completely abolished it in vitro , supporting the specificity of this interaction. Mutations in the binding interface increased sensitivity to chloramphenicol. This phenotype was suppressed by rpoB *35, an RNAP mutation that reduces replisome‐RNAP clashes. We propose that weakened NusG:S10 interaction leads to uncoupling when translation is inhibited, with resulting RNAP backtracking, replication blocks and formation of lethal DNA double‐strand breaks.