Functional Analysis of the p40 and p75 Proteins from <i>Lactobacillus casei</i> BL23

Abstract

The genomes of Lactobacillus casei/paracasei and Lactobacillus rhamnosus strains carry two genes encoding homologues of p40 and p75 from L. rhamnosus GG, two secreted proteins which display anti-apoptotic and cell protective effects on human intestinal epithelial cells. p40 and p75 carry cysteine, histidine-dependent aminohydrolase/peptidase (CHAP) and NLPC/P60 domains, respectively, which are characteristic of proteins with cell-wall hydrolase activity. In L. casei BL23 both proteins were secreted to the growth medium and were also located at the bacterial cell surface. The genes coding for both proteins were inactivated in this strain. Inactivation of LCABL_00230 (encoding p40) did not result in a significant difference in phenotype, whereas a mutation in LCABL_02770 (encoding p75) produced cells that formed very long chains. Purified glutathione-S-transferase (GST)-p40 and -p75 fusion proteins were able to hydrolyze the muropeptides from L. casei cell walls. Both fusions bound to mucin, collagen and to intestinal epithelial cells and, similar to L. rhamnosus GG p40, stimulated epidermal growth factor receptor phosphorylation in mouse intestine ex vivo. These results indicate that extracellular proteins belonging to the machinery of cell-wall metabolism in the closely related L. casei/paracasei-L. rhamnosus group are most likely involved in the probiotic effects described for these bacteria

Comparative Genomic and Functional Analysis of Lactobacillus casei and Lactobacillus rhamnosus Strains Marketed as Probiotics

“…Comparative genome analysis has shown that L. rhamnosus and L. casei genomes are highly related (4). This is illustrated by the observation that not only L. rhamnosus but also L. casei strains produce highly identical MspI (p75) and Msp2 (p40) proteins that have similar functions in both species (19,20). However, in spite of the fact that strains of L. casei are widely marketed as probiotics (5), the genomes of many commercial L. casei strains have yet to be reported.…”

A Lactobacillus rhamnosus GG-derived Soluble Protein, p40, Stimulates Ligand Release from Intestinal Epithelial Cells to Transactivate Epidermal Growth Factor Receptor

“…Sequence analysis of p40 revealed that the N terminus of p40 contains an uncharacterized protein domain conserved in bacteria, whereas the C-terminal region of p40 exhibits high homology to a cysteine, histidine-dependent amidohydrolase/ peptidase domain (14). Further characterization of p40 showed that p40 in Lactobacilllus casei BL23 is located at the bacterial cell surface, is secreted to the culture media, and is able to hydrolyze the muropeptides from L. casei cell walls (15), whereas another study reported that p40 has D-glutamyl-L-lysyl endopeptidase activity (16,17).…”

Lactobacillus spp. belonging to the Casei group display a variety of adhesins

“…This strain has two homologous proteins, p75 and p40, which exhibit cell wall hydrolase activity, and contains the NLPC/P60 domain. These proteins influence probiotic properties of a strain by stimulating the Akt kinase activity in the intestinal epithelium, and they show antiapoptotic properties (Gilad et al, 2011;Yan et al, 2007), as well as the capacity to bind mucins, collagen and to adhere to enterocytes (Bäuerl et al, 2011). The cold shock proteins (Csp), identified in the L. casei Fyos isolate may serve as adhesins for the mucus, as the strain adheres effectively only to the mucus.…”