Identification of novel proteins secreted by Lactobacillus rhamnosus GG grown in de Mann-Rogosa-Sharpe broth.
OBJECTIVE
To identify novel proteins secreted by the probiotic bacterium Lactobacillus rhamnosus GG after growth in de Mann-Rogosa-Sharpe broth (MRS), a complex medium often used for the culture of Lactobacillus.


RESULTS
The proteins secreted by L. rhamnosus GG strain were precipitated using a trichloroacetic acid-based protocol, resolved by SDS-PAGE, and identified by tandem mass spectrometry (MS/MS). Among the proteins secreted by this bacterium, a leukocyte elastase inhibitor, already present in the MRS broth, was identified. Other proteins such as cell wall hydrolase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate kinase, and an extracellular transcriptional regulator have been also identified.


CONCLUSIONS
Lactobacillus rhamnosus GG secretes several proteins during its growth in MRS, some of them with assigned functions in the prevention of the molecular mechanisms that lead to damage in the epithelial barrier (cell wall hydrolase) and in adhesion (GAPDH). The rest of the proteins require further genetic analysis in order to establish their precise roles. None of the proteins bound to mucin or fibronectin.


CONCLUSIONS
Some of these secreted proteins could be involved in the probiotic effects exerted by L. rhamnosus GG strain, their identification being the first step towards in depth functional studies.
Sánchez
B
B
Université de Bordeaux, UMR 5248 CNRS, UBX1-ENITAB, ENITAB, Gradignan Cedex, France. b-sanchez@enitab.fr
Schmitter
J-M
JM
Urdaci
M C
MC
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism*; D007778:Lactobacillus / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D021381:Protein Transport
D001426:Bacterial Proteins; D003470:Culture Media