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A cis ‐acting antitoxin domain within the chromosomal toxin–antitoxin module EzeT of E scherichia coli quenches toxin activity
Summary Toxin–antitoxin ( TA ) systems are widespread genetic modules in the genomes of bacteria and archaea emerging as key players that modulate bacterial physiology. They consist of two parts, a toxic component that blocks an essential cellular process and an antitoxin that inhibits this toxic ac...
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Published in: | Molecular microbiology 2015-08, Vol.97 (3), p.589-604 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Summary
Toxin–antitoxin (
TA
) systems are widespread genetic modules in the genomes of bacteria and archaea emerging as key players that modulate bacterial physiology. They consist of two parts, a toxic component that blocks an essential cellular process and an antitoxin that inhibits this toxic activity during normal growth. According to the nature of the antitoxin and the mode of inhibition,
TA
systems are subdivided into different types. Here, we describe the characterization of a type
II
‐like
TA
system in
E
scherichia coli
called
EzeT
. While in conventional type
II
systems the antitoxin is expressed in
trans
to form an inactive protein–protein complex,
EzeT
consists of two domains combining toxin and
cis‐
acting antitoxin functionalities in a single polypeptide chain. We show that the
C
‐terminal domain of
EzeT
is homologous to zeta toxins and is toxic
in vivo
. The lytic phenotype could be attributed to
UDP
‐
N
‐acetylglucosamine phosphorylation, so far only described for type
II
epsilon/zeta systems from
G
ram‐positive streptococci. Presence of the
N
‐terminal domain inhibits toxicity
in vivo
and strongly attenuates kinase activity. Autoinhibition by a
cis
‐acting antitoxin as described here for
EzeT
‐type
TA
systems can explain the occurrence of single or unusually large toxins, further expanding our understanding of the
TA
system network. |
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ISSN: | 0950-382X 1365-2958 |
DOI: | 10.1111/mmi.13051 |