Our
current
understanding
of
virulence
in
the
opportunistic
pathogen
Candida
glabrata
is
in
its
infancy.
To
expand
our
understanding
of
C.
glabrata
virulence,
an
investigation
into
the
genes
transcriptionally
regulated
by
the
first
virulence-moderating
gene
to
be
discovered
in
Candida,
ACE2,
was
undertaken.
For
the
first
time
in
C.
glabrata,
a
partial
Ace2p
regulon
containing
12
previously
univestigated
genes
that
show
Ace2p‐dependent
expression
has
been
defined.
Study
of
their
promoter
regions
discovered
possible
Ace2p
DNA
binding
sites,
with
10
genes
showing
possible
direct
regulation
by
Ace2p
in
C.
glabrata.
A
reductionist
approach
was
employed
in
an
effort
to
study
the
effects
of
the
deletion
of
each
of
the
12
partial
Ace2p-regulon
genes
in
C.
glabrata
individually.
Both
phenotypic
and
virulence
analyses
were
used
to
analyse
the
results
of
the
individual
deletions
with
regard
to
the
extreme
hypervirulence
displayed
by
the
ace2
null
cells.
The
results
indicate
that
out
of
the
10
genes
successfully
disrupted,
six
were
shown
to
be
significantly
different
when
compared
with
the
C.
glabrata
wild
type
in
a
neutropenic
murine
model
of
systemic
candidiasis
and
therefore
hypervirulent.
Each
of
the
six
hypervirulent
genes
showed
100%
mortality
after
five
days
post
infection,
markedly
different
to
the
hypervirulence
displayed
by
the
ace2
null,
which
displayed
100%
mortality
within
18
hours
post
infection,
and
to
the
wild
type,
which
displayed
40%
mortality
after
14
days
post
infection.
The
C.
glabrata
sic1
null
was
also
found
to
elicit
significantly
increased
cytokine
release
in
an
in
vitro
macrophage
infection
assay,
as
measured
by
IL‐6
and
TNFα
ELISA.
The
results
presented
in
this
thesis
therefore
indicate
that
the
hypervirulence
and
immune
over-stimulation
shown
by
the
ace2
mutant
in
C.
glabrata
is
most
likely
multifactorial
with
a
combination
of
antivirulence
genes
contributing
to
the
extreme
hypervirulence
and
immune
over-stimulation.
During
the
course
of
investigation
into
the
Ace2p
regulon,
a
novel
gene
lacking
homology
to
putative
glucanases
or
other
yeast
genes
was
highlighted.
Therefore
the
uncharacterised
Ace2p
regulon
gene
DSE1,
whose
function
is
currently
unknown,
was
investigated.
Using
C.
glabrata
and
its
close
genetic
relative,
the
model
organism
Saccharomyces
cerevisiae,
a
study
of
the
localisation,
phenotype
and
structural
prediction
revealed
a
possible
enzymatic
or
regulatory
function
for
Dse1p,
localised
to
the
cell
budding
area
and
daughter
cell,
with
a
likely
role
in
cell
wall
metabolism
and
cell
separation
within
C.
glabrata
