Differential composition of culture supernatants from wild-type Brucella abortus and its isogenic virB mutants.
The virB genes coding type IV secretion system are necessary for the intracellular survival and replication of Brucella spp. In this study, extracellular proteins from B. abortus 2308 (wild type, WT) and its isogenic virB10 polar mutant were compared. Culture supernatants harvested in the early stationary phase were concentrated and subjected to 2D electrophoresis. Spots present in the WT strain but absent in the virB10 mutant (differential spots) were considered extracellular proteins released in a virB-related manner, and were identified by MALDI-TOF analysis and matching with Brucella genomes. Among the 11 differential proteins identified, DnaK chaperone (Hsp70), choloylglycine hydrolase (CGH) and a peptidyl-prolyl cis-trans isomerase (PPIase) were chosen for further investigation because of their homology with extracellular and/or virulence factors from other bacteria. The three proteins were obtained in recombinant form and specific monoclonal antibodies (mAbs) were prepared. By Western blot with these mAbs, the three proteins were detected in supernatants from the WT but not in those from the virB10 polar mutant or from strains carrying non-polar mutations in virB10 or virB11 genes. These results suggest that the expression of virB genes affects the extracellular release of DnaK, PPIase and CGH, and possibly other proteins from B. abortus.
IDEHU, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junin 956, 4to. Piso, 1113 Buenos Aires, Argentina.
M Victoria
MV
Delpino
Diego J
DJ
Comerci
Mary Ann
MA
Wagner
Michel
M
Eschenbrenner
Cesar V
CV
Mujer
Rodolfo A
RA
Ugalde
Carlos A
CA
Fossati
Pablo C
PC
Baldi
Vito G
VG
Delvecchio
D000581:Amidohydrolases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002003:Brucella abortus / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D002460:Cell Line; D003470:Culture Media; D015180:Electrophoresis, Gel, Two-Dimensional; D005798:Genes, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase / Q000378:metabolism; D040901:Proteomics; D016415:Sequence Alignment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D003470:Culture Media; D018840:HSP70 Heat-Shock Proteins; D037521:Virulence Factors; D000581:Amidohydrolases; C023154:choloylglycine hydrolase; D019696:Peptidylprolyl Isomerase