title: Effect of acid stress on protein expression and phosphorylation in Lactobacillus rhamnosus GG.
abstract: Acidic environments encountered in food products and during gastrointestinal tract passage affect the survival of bacteria that are marketed as probiotics. In this study, the global proteome responses of the probiotic lactic acid bacterium Lactobacillus rhamnosus GG to two physiologically relevant pH conditions (pH 4.8 and pH 5.8) were studied by 2-D DIGE. The proteomics data were complemented with transcriptome analyses by whole-genome DNA microarrays. The cells were cultured in industrial-type whey medium under strictly defined bioreactor conditions. In total, 2-D DIGE revealed the pH-dependent formation of 92 protein spots. In response to lower pH conditions, the strongest up-regulation of all proteins was detected for a predicted surface antigen, LGG_02016. In addition, the acid pH was found to up-regulate the expression of F(0)F(1)-ATP synthase genes whereas the abundance of proteins participating in nucleotide biosynthesis and protein synthesis was significantly diminished. Moreover, the results suggest that L. rhamnosus GG modulates its pyruvate metabolism depending on the growth pH. Furthermore, a growth pH-dependent protein phosphorylation phenomenon was detected in several L. rhamnosus GG proteins with ProQ Diamond 2-DE gel staining. Proteins participating in central cellular pathways were shown to be phosphorylated, and the phosphorylation of glycolytic enzymes was found to be especially extensive.
authors: Institute of Biotechnology, University of Helsinki, Helsinki, Finland.
authors: Johanna
authors: J
authors: Koponen
authors: Kati
authors: K
authors: Laakso
authors: Kerttu
authors: K
authors: Koskenniemi
authors: Matti
authors: M
authors: Kankainen
authors: Kirsi
authors: K
authors: Savijoki
authors: Tuula A
authors: TA
authors: Nyman
authors: Willem M
authors: WM
authors: de Vos
authors: Soile
authors: S
authors: Tynkkynen
authors: Nisse
authors: N
authors: Kalkkinen
authors: Pekka
authors: P
authors: Varmanen
mesh_terms: D000143:Acids / Q000737:chemistry; D019149:Bioreactors; D018076:DNA, Complementary / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006019:Glycolysis; D006863:Hydrogen-Ion Concentration; D052201:Lacticaseibacillus rhamnosus / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D040901:Proteomics / Q000379:methods; D012313:RNA / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000143:Acids; D018076:DNA, Complementary; D012313:RNA