Functional characterization of the Bacillus subtilis conjugative plasmid pLS20: identification of relaxosome components and mechanism of transcriptional control of main conjugation promoter Pc
Autor (es)
Ramachandran, GayetriDirector (es)
Meijer, Wihelmus J. J.Entidad
UAM. Departamento de Biología Molecular; Centro de Biología Molecular Severo Ochoa (CBM)Fecha de edición
2015-03-13Materias
Bacilus subtilis - Tesis doctorales; Biología y Biomedicina / BiologíaNota
Tesis doctoral inédita leída en la Universida Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 13-03-2015
Esta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
Resumen
Plasmid
conjugation
plays
a
significant
role
in
the
dissemination
of
antibiotic
resistance
and
pathogenicity
determinants.
Understanding
how
conjugation
is
regulated
is
important
to
gain
insights
into
these
features.
Little
is
known
about
regulation
of
conjugation
systems
present
on
plasmids
from
Gram-‐positive
bacteria.
The
plasmid
pLS20
is
a
native
conjugative
plasmid
isolated
from
Bacillus
subtilis
“natto”.
Our
earlier
laboratory
results
reported
a
global
view
of
the
regulatory
system
of
the
pLS20
conjugation
genes.
It
was
found
that
about
40
conjugation
genes
were
regulated
by
a
divergently
oriented
single
gene
rcoLS20,
which
encodes
for
the
master
regulator
of
conjugation.
RcoLS20
is
responsible
for
keeping
the
system
in
its
default
“OFF”
state.
Conjugation
is
activated
by
anti-‐repressor
RapLS20,
which
belongs
of
the
family
of
Rap
proteins.
However,
the
activity
of
RapLS20
is
regulated
by
a
signaling
peptide
Phr*LS20.
Even
though,
the
key
players
involved
in
the
regulation
of
the
conjugation
genes
have
been
identified,
our
knowledge
on
regulation
of
the
genetic
switch
responsible
for
activating
conjugation
is
limited.
In
the
first
chapter
of
the
thesis,
we
have
studied
in
detail
the
molecular
mechanism
regulating
the
pLS20
conjugation
genes
using
different
in
vivo
and
in
vitro
approaches.
At
least
three
levels
of
regulation
controls
plasmid
mediated-‐
conjugation
including
overlapping
and
divergent
promoter
of
differing
strengths,
maintaining
the
expression
of
the
genes
of
conjugation
and
repression,
along
with
a
tri-‐functional
repressor
RcoLS20,
which
regulates
its
own
transcription
and
finally
as
a
tetramer
RcoLS20,
by
DNA-‐looping.
These
complex
regulatory
levels
permits
the
switching
“OFF”
and
“ON”
of
the
system
of
conjugation.
The
second
chapter
of
the
thesis
studies
the
formation
of
the
relaxosome
of
plasmid
pLS20.
This
nucleoprotein
is
essential
during
conjugation,
permitting
the
transfer
of
DNA.
In
case
of
plasmid
pLS20,
we
found
that
besides
the
relaxase,
encoded
by
gene
58
of
pLS20,
and
that
we
named
RelLS20,
the
functional
processing
of
oriT
requires
two
additional
proteins
encoded
by
genes
56
and
57.
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Google Scholar:Ramachandran, Gayetri
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