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The intestinal epithelium is considered the first defense protection against exogenous harmful substances, playing an indispensable role in regulating intestinal health. The protection offered by surface-layer proteins (Slps) from different Lactobacillus strains on an impaired intestinal barrier was investigated in this study.Four Slps pre-incubated for 6 h significantly prevented the reduced transepithelial electrical resistance value and increased paracellular permeability in tumor necrosis factor (TNF)-α-induced Caco-2 monolayers. TNF-α induced lower protein expression of occludin and zonula occludens-1, and abnormal distributions of occludin and zonula occludens-1 were ameliorated by four Slps as well. Additionally, four Slps weakened TNF-α-evoked interleukin-8 secretion and nuclear factor-κB activation.Four Slps from different strains prevent the intestinal barrier from TNF-α-induced dysfunction through blocking the nuclear factor-κB signaling pathway. © 2022 Society of Chemical Industry.

Saline-alkali soil is a major environmental constraint impairing plant growth and crop productivity. In this study, we identified a Ca2+ sensor/kinase/plasma membrane (PM) H+-ATPase module as a central component conferring alkali tolerance in Arabidopsis (Arabidopsis thaliana). We report that the SCaBP3 (SOS3-LIKE CALCIUM BINDING PROTEIN3)/CBL7 (CALCINEURIN B-LIKE7) loss-of-function plants exhibit enhanced stress tolerance associated with increased PM H+-ATPase activity and provide fundamental mechanistic insights into the regulation of PM H+-ATPase activity. Consistent with the genetic evidence, interaction analyses, in vivo reconstitution experiments, and determination of H+-ATPase activity indicate that interaction of the Ca2+ sensor SCaBP3 with the C-terminal Region I domain of the PM H+-ATPase AHA2 (Arabidopsis thaliana PLASMA MEMBRANE PROTON ATPASE2) facilitates the intramolecular interaction of the AHA2 C terminus with the Central loop region of the PM H+-ATPase to promote autoinhibition of H+-ATPase activity. Concurrently, direct interaction of SCaPB3 with the kinase PKS5 (PROTEIN KINASE SOS2-LIKE5) stabilizes the kinase-ATPase interaction and thereby fosters the inhibitory phosphorylation of AHA2 by PKS5. Consistently, yeast reconstitution experiments and genetic analysis indicate that SCaBP3 provides a bifurcated pathway for coordinating intramolecular and intermolecular inhibition of PM H+-ATPase. We propose that alkaline stress-triggered Ca2+ signals induce SCaBP3 dissociation from AHA2 to enhance PM H+-ATPase activity. This work illustrates a versatile signaling module that enables the stress-responsive adjustment of plasma membrane proton fluxes.

In recent years, studies on immunomodulation by surface-layer proteins (Slps) have mainly focused on Lactobacillus acidophilus, there is little information on Slp from L. crispatus and its intestinal immunomodulatory mechanisms in macrophages. In our study, the anti-inflammatory actions of Slp derived from L. crispatus JCM 2009 and its related molecular mechanisms were investigated. We initially found that incubation with Slp (5–10 μg/mL) for 4 h significantly inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) production in LPS-stimulated RAW264.7 cells (P

The objective of this study was to evaluate the bactericidal effects of surface-layer protein (Slp) derived from Lactobacillus acidophilus NCFM, L. acidophilus CGMCC1.1878 in combination with nisin against Staphylococcus aureus and investigate their antibacterial mechanism. Compared with the nisin (MIC, 300 IU/mL) alone treatment, the Slps (50 μg/mL) + nisin (1/2 MIC, 150 IU/mL) treatment effectively inhibited S. aureus growth and significantly enhanced its cell membrane permeability (P

Saline-alkali soil is a major environmental constraint impairing plant growth and crop productivity. In this study, we identified a Ca(2+) sensor/kinase/plasma membrane (PM) H(+)-ATPase module as a central component conferring alkali tolerance in Arabidopsis (Arabidopsis thaliana). We report that the SCaBP3 (SOS3-LIKE CALCIUM BINDING PROTEIN3)/CBL7 (CALCINEURIN B-LIKE7) loss-of-function plants exhibit enhanced stress tolerance associated with increased PM H(+)-ATPase activity and provide fundamental mechanistic insights into the regulation of PM H(+)-ATPase activity. Consistent with the genetic evidence, interaction analyses, in vivo reconstitution experiments, and determination of H(+)-ATPase activity indicate that interaction of the Ca(2+) sensor SCaBP3 with the C-terminal Region I domain of the PM H(+)-ATPase AHA2 (Arabidopsis thaliana PLASMA MEMBRANE PROTON ATPASE2) facilitates the intramolecular interaction of the AHA2 C terminus with the Central loop region of the PM H(+)-ATPase to promote autoinhibition of H(+)-ATPase activity. Concurrently, direct interaction of SCaPB3 with the kinase PKS5 (PROTEIN KINASE SOS2-LIKE5) stabilizes the kinase-ATPase interaction and thereby fosters the inhibitory phosphorylation of AHA2 by PKS5. Consistently, yeast reconstitution experiments and genetic analysis indicate that SCaBP3 provides a bifurcated pathway for coordinating intramolecular and intermolecular inhibition of PM H(+)-ATPase. We propose that alkaline stress-triggered Ca(2+) signals induce SCaBP3 dissociation from AHA2 to enhance PM H(+)-ATPase activity. This work illustrates a versatile signaling module that enables the stress-responsive adjustment of plasma membrane proton fluxes.