Cross-talk between Type Three Secretion System and Metabolism in YersiniaS

• Published in: The Journal of biological chemistry Vol. 284; no. 18; pp. 12165 - 12177
• Main Authors: Schmid, Annika, Neumayer, Wibke, Trülzsch, Konrad, Israel, Lars, Imhof, Axel, Roessle, Manfred, Sauer, Guido, Richter, Susanna, Lauw, Susan, Eylert, Eva, Eisenreich, Wolfgang, Heesemann, Jürgen, Wilharm, Gottfried
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 01-05-2009
• Subjects: Metabolism and Bioenergetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M900773200

Pathogenic yersiniae utilize a type three secretion system (T3SS) to inject
Yop proteins into host cells in order to undermine their immune response.
YscM1 and YscM2 proteins have been reported to be functionally equivalent
regulators of the T3SS in
Yersinia enterocolitica
. Here, we show by
affinity purification, native gel electrophoresis and small angle x-ray
scattering that both YscM1 and YscM2 bind to phosphoenolpyruvate carboxylase
(PEPC) of
Y. enterocolitica
. Under
in vitro
conditions,
YscM1, but not YscM2, was found to inhibit PEPC with an apparent
IC
50
of 4 μ
m
(
K
i
= 1
μ
m
). To analyze the functional roles of PEPC, YscM1, and YscM2
in Yop-producing bacteria, cultures of
Y. enterocolitica
wild type
and mutants defective in the formation of PEPC, YscM1, or YscM2, respectively,
were grown under low calcium conditions in the presence of
[U-
13
C
6
]glucose. The isotope compositions of secreted
Yop proteins and nine amino acids from cellular proteins were analyzed by mass
spectrometry. The data indicate that a considerable fraction of oxaloacetate
used as precursor for amino acids was derived from
[
13
C
3
]phosphoenolpyruvate by the catalytic action of
PEPC in the wild-type strain but not in the PEPC
-
mutant. The data
imply that PEPC is critically involved in replenishing the oxaloacetate pool
in the citrate cycle under virulence conditions. In the YscM1
-
and
YscM2
-
mutants, increased rates of pyruvate formation via
glycolysis or the Entner-Doudoroff pathway, of oxaloacetate formation via the
citrate cycle, and of amino acid biosynthesis suggest that both regulators
trigger the central metabolism of
Y. enterocolitica
. We propose a
“load-and-shoot cycle” model to account for the cross-talk between
T3SS and metabolism in pathogenic yersiniae.