Identification of stress-inducible proteins in Lactobacillus delbrueckii subsp. bulgaricus.
Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) is a homofermentative bacterium that produces lactic acid during growth. We adapted the two-dimensional electrophoresis (2-DE) technique to study the response of this bacterium to acidity. De novo protein synthesis was monitored by [35S]methionine labeling of exponentially growing cultures under standard (pH 6) and acidic (pH 4.75) conditions. After 2-DE separation, the protein patterns were compared. The protein spots showing increased radioactivity levels under acid conditions were considered acid-induced. We determined the N-terminal amino acid sequence of three highly induced proteins; comparing these proteins to databases we identified them to be the well-known heat shock proteins GroES, GroEL, and DnaK. Their induction levels were measured and compared. This is the first study by 2-DE of stress response in L. bulgaricus. We established the method and present a protein map which will be useful for future studies.
Lim
E M
EM
Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy-en-Josas, France. emlim@biotec.jouy.inra.fr
Ehrlich
S D
SD
Maguin
E
E
D000143:Acids; D001426:Bacterial Proteins / Q000032:analysis*; D018835:Chaperonin 10 / Q000032:analysis*; D018834:Chaperonin 60 / Q000032:analysis*; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis*; D007778:Lactobacillus / Q000737:chemistry*
D000143:Acids; D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; C063842:dnaK protein, E coli