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Medientyp:
E-Artikel
Titel:
The insect endosymbiont Sodalis glossinidius utilizes a type III secretion system for cell invasion
Beteiligte:
Dale, Colin;
Young, Simon A.;
Haydon, Daniel T.;
Welburn, Susan C.
Erschienen:
Proceedings of the National Academy of Sciences, 2001
Erschienen in:Proceedings of the National Academy of Sciences
Sprache:
Englisch
DOI:
10.1073/pnas.98.4.1883
ISSN:
0027-8424;
1091-6490
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>
<jats:italic>Sodalis glossinidius</jats:italic>
is a maternally transmitted
secondary endosymbiont residing intracellularly in tissues of the
tsetse flies,
<jats:italic>Glossina</jats:italic>
spp. In this study, we have used
Tn5 mutagenesis and a negative selection procedure to derive a
<jats:italic>S. glossinidius</jats:italic>
mutant that is incapable of invading
insect cells
<jats:italic>in vitro</jats:italic>
and is aposymbiotic when
microinjected into tsetse. This mutant strain harbors Tn5 integrated
into a chromosomal gene sharing high sequence identity with a type III
secretion system invasion gene (
<jats:italic>invC</jats:italic>
) previously
identified in
<jats:italic>Salmonella enterica</jats:italic>
. With the use of
degenerate PCR, we have amplified a further six
<jats:italic>Sodalis
inv</jats:italic>
/
<jats:italic>spa</jats:italic>
genes sharing high sequence identity
with type III secretion system genes encoded by
<jats:italic>Salmonella</jats:italic>
pathogenicity island 1. Phylogenetic
reconstructions based on the
<jats:italic>inv</jats:italic>
/
<jats:italic>spa</jats:italic>
genes of
<jats:italic>Sodalis</jats:italic>
and other members of the family
<jats:italic>Enterobacteriaceae</jats:italic>
have consistently identified a
well-supported clade containing
<jats:italic>Sodalis</jats:italic>
and the enteric
pathogens
<jats:italic>Shigella</jats:italic>
and
<jats:italic>Salmonella</jats:italic>
. These
results suggest that
<jats:italic>Sodalis</jats:italic>
may have evolved from an
ancestor with a parasitic intracellular lifestyle, possibly a
latter-day entomopathogen. These observations lend credence to a
hypothesis suggesting that vertically transmitted mutualistic
endosymbionts evolve from horizontally transmitted parasites through a
parasitism–mutualism continuum.
</jats:p>