Periplasmic superoxide dismutase SodCI of S almonella binds peptidoglycan to remain tethered within the periplasm
Salmonellae survive and propagate in macrophages to cause serious systemic disease. Periplasmic superoxide dismutase plays a critical role in this survival by combating phagocytic superoxide. Salmonella Typhimurium strain 14028 produces two periplasmic superoxide dismutases: SodCI and SodCII . Altho...
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Veröffentlicht in: | Molecular microbiology 2015-09, Vol.97 (5), p.832-843 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Salmonellae
survive and propagate in macrophages to cause serious systemic disease. Periplasmic superoxide dismutase plays a critical role in this survival by combating phagocytic superoxide.
Salmonella
Typhimurium strain 14028 produces two periplasmic superoxide dismutases:
SodCI
and
SodCII
. Although both proteins are produced during infection, only
SodCI
is functional in the macrophage phagosome. We have previously shown that
SodCI
, relative to
SodCII
, is both protease resistant and tethered within the periplasm and that either of these properties is sufficient to allow a
SodC
to protect against phagocytic superoxide. Tethering is defined as remaining cell‐associated after osmotic shock or treatment with cationic antimicrobial peptides. Here we show that
SodCI
non‐covalently binds peptidoglycan.
SodCI
binds to
Salmonella
and
Bacillus
peptidoglycan, but not peptidoglycan from
Staphylococcus
. Moreover, binding can be inhibited by a diaminopimelic acid containing tripeptide, but not a lysine containing tripeptide, showing that the protein recognizes the peptide portion of the peptidoglycan. Replacing nine amino acids in
SodCII
with the corresponding residues from
SodCI
confers tethering, partially delineating an apparently novel peptidoglycan binding domain. These changes in sequence increase the affinity of
SodCII
for peptidoglycan fragments to match that of
SodCI
and allow the now tethered
SodCII
to function during infection. |
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ISSN: | 0950-382X 1365-2958 |
DOI: | 10.1111/mmi.13067 |