47 Pages
English
Gain access to the library to view online
Learn more

Functional genomics of food-borne pathogens [Elektronische Ressource] / vorgelegt von Thilo M. Fuchs

-

Gain access to the library to view online
Learn more
47 Pages
English

Description

Functional genomics of food-borne pathogens Habilitationsschrift vorgelegt von Thilo M. Fuchs Lehrstuhl für Mikrobielle Ökologie Department für Biowissenschaftliche Grundlagen Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt Freising 2006 Contents page 1. Summary 1 2. Introduction: functional genomics 2 3. Genome-wide insertional-duplication mutagenesis (IDM) 8 4. The essential genes set of Salmonella typhimurium 12 5. Intracellular replication of Listeria monocytogenes 19 6. Association of Yersinia enterocolitica with invertebrates 24 7. Acknowledgement 31 8. Bibliography 32 9. Author’s publications and patents 39 10. Curriculum vitae 42 11. Appendix: selected publications 44 Summary The growing number of complete microbial genome sequences and the ready availability of their annotation provide a powerful data base for studying the biology of microorganisms. In this work, two distinct high-throughput approaches are described to exploit genomics of pathogenic bacteria, insertional-duplication mutagenesis (IDM) and expression profiling using the luciferase reporter system.

Subjects

Informations

Published by
Published 01 January 2006
Reads 16
Language English

Exrait

Functional genomics
of food-borne pathogens
Habilitationsschrift
vorgelegt von
Thilo M.
F
u
c
h
s
Lehrstuhl für Mikrobielle Ökologie
Department für Biowissenschaftliche Grundlagen
Fakultät Wissenschaftszentrum Weihenstephan für Ernährung,
Landnutzung und Umwelt
Freising
2006
Contents
page
1.
Summary
1
2.
Introduction: functional genomics
2
3.
Genome-wide insertional-duplication mutagenesis (IDM)
8
4.
The essential genes set of
Salmonella typhimurium
12
5.
Intracellular replication of
Listeria monocytogenes
19
6.
Association of
Yersinia enterocolitica
with invertebrates
24
7.
Acknowledgement
31
8.
Bibliography
32
9.
Author’s publications and patents
39
10.
Curriculum vitae
42
11. Appendix: selected publications
44
1
Summary
The growing number of complete microbial genome sequences and the ready availability
of their annotation provide a powerful data base for studying the biology of
microorganisms. In this work, two distinct high-throughput approaches are described
t
o
e
x
p
l
o
i
t
g
e
n
o
m
i
c
s
o
f
pathogenic bacteria,
i
n
s
e
r
t
i
o
n
a
l-duplication mutagenesis (IDM)
a
n
d
expression profiling using the luciferase reporter
s
y
s
t
e
m. Their genome-wide application
t
o
t
h
e
f
o
o
d-borne pathogens
Salmonella typhimurium
,
Listeria
m
o
n
o
c
y
t
o
g
e
n
e
s
a
n
d
Yersinia enterocolitica
led to new insights into the complex world of microbial life in terms
of (I) the minimal gene set, (II) intracellularly required factors, and (III) the association
with invertebrates.
I)
Minimalism
: The essential gene set of
S. typhimurium
was defined by a no
v
e
l
g
e
n
e
t
i
c
strategy. Small, randomly generated chromosomal fragments of this pathogen
w
e
r
e
cloned into a temperature-sensitive vector, and the resulting mutagenic library was
grown under permissive conditions. Upon switching to non-permissive temperature,
genes with essential functions under laboratory conditions could be trapped following
discrimination between lethal and non-lethal recombination events. Further
characterization of a total of ~500 fragments revealed 145 known essential genes and
112 functionally characterised or hypothetical genes not yet demonstrated to be essential
for a bacterial cell
;
t
h
i
s
n
u
m
b
e
r
c
o
r
r
e
s
p
o
n
d
s
t
o
a
p
p
r
o
x
i
m
a
t
e
l
y
1
1
%
o
f
t
h
e
Salmonella
genome.
II)
Specialization
: More than
1,000 IDM mutants
o
f
t
h
e facultative intracellular
pathogen
L. monocytogenes
were screened for their phenotypes in human epithelial cells.
The genetic analysis of severely attenuated mutants revealed a huge number of listerial
g
e
n
e
s
required for replication in non-phagocytic cells, thus dissecting the genome of
Listeria
in
t
e
r
m
s
o
f
t
h
e
i
r
a
d
a
p
t
a
t
i
o
n
t
o
t
h
e
i
n
t
r
a
c
e
l
l
u
l
a
r
e
n
v
i
r
o
n
m
e
n
t
.
T
h
e
acquisition of
species-specific genes and the usage of alternative sugar and nitrogen sources could be
demonstrated as novel strategies that enable this pathogen to survive in
t
h
e
c
y
t
o
s
o
l
o
f
the host cell
.
III)
Associ
a
t
ion
: A promoter fusion library of
Y. enterocolitica
was constructed by the
transposon-mediated chromosomal insertion of the luciferase reporter
,
a
n
d
t
h
e
transcriptional response of
t
h
e
genome was derived when cells were exposed to low
temperatures
. Sequence analysis revealed a novel pathogenicity island termed
t
c
-PAI
Y
e
carrying insecticidal toxin genes that could be demonstrated to be transcriptionally silent
at body temperature, but to be essential for
Y
.
e
n
t
e
r
o
c
o
l
i
t
i
c
a
toxicity against insects at
low temperature. This data demonstrates a yet unknown
p
a
t
h
o
g
e
n
i
c
i
t
y phase of
Y.
enterocolitica
in insects, suggesting invertebrates as a potential
s
o
u
r
c
e
o
f pathogen
evolution.