Cross-talk between type three secretion system and metabolism in Yersinia.
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 mum (K(i) = 1 mum). 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.
Schmid
Annika
A
Department of Bacteriology, Max von Pettenkofer-Institute for Hygiene and Medical Microbiology, Pettenkoferstrasse 9a, D-80336 Munich, Germany.
Neumayer
Wibke
W
Trülzsch
Konrad
K
Israel
Lars
L
Imhof
Axel
A
Roessle
Manfred
M
Sauer
Guido
G
Richter
Susanna
S
Lauw
Susan
S
Eylert
Eva
E
Eisenreich
Wolfgang
W
Heesemann
Jürgen
J
Wilharm
Gottfried
G
D000596:Amino Acids / Q000096:biosynthesis / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002952:Citric Acid Cycle / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D006019:Glycolysis / Q000187:drug effects / Q000502:physiology; D062907:Oxaloacetic Acid / Q000378:metabolism; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D055571:Secretory Pathway / Q000187:drug effects / Q000502:physiology*; D013549:Sweetening Agents / Q000378:metabolism / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015008:Yersinia enterocolitica / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*
D000596:Amino Acids; D001426:Bacterial Proteins; D013549:Sweetening Agents; D014157:Transcription Factors; C110346:YscM1 protein, Yersinia enterocolitica; C110345:YscM2 protein, Yersinia enterocolitica; D062907:Oxaloacetic Acid; D019289:Pyruvic Acid; D010730:Phosphoenolpyruvate Carboxylase; D005947:Glucose; D002118:Calcium