Decline in ribosomal fidelity contributes to the accumulation and stabilization of the master stress response regulator sigma S upon carbon starvation

• The {sigma}S subunit of RNA polymerase is a master regulator of Escherichia coli that retards cellular senescence and bestows cells with general stress protective functions during growth arrest. We show that mutations and drugs triggering translational errors elevate {sigma}S levels and stability. Furthermore, mutations enhancing translational fidelity attenuate induction of the rpoS regulon and prevent stabilization of {sigma}S upon carbon starvation. Destabilization of {sigma}S by increased proofreading requires the presence of the {sigma}S recognition factor SprE (RssB) and the ClpXP protease. The data further suggest that {sigma}S becomes stabilized upon starvation as a result of ClpP sequestration and this sequestration is enhanced by oxidative modifications of aberrant proteins produced by erroneous translation. ClpP overproduction counteracted starvation-induced stabilization of {sigma}S, whereas overproduction of a ClpXP substrate (ssrA-tagged GFP) stabilized {sigma}S in exponentially growing cells. We present a model for the sequence of events leading to the accumulation and activation of {sigma}S upon carbon starvation, which are linked to alterations in both ribosomal fidelity and efficiency.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Escherichia coli

stationary phase

RpoS

SprE

rpsL

ClpP

protein oxidation

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)