A Collagen-Binding S-Layer Protein in Lactobacillus crispatus

Area of Science:

• Microbiology
• Biochemistry
• Cell Biology

Background:

• The extracellular matrix (ECM) plays a crucial role in cell adhesion and tissue structure.
• Lactic acid bacteria (LAB) interact with host tissues, influencing gut health.
• S-layers are proteinaceous surface layers found on many bacteria, involved in adhesion and immune interactions.

Purpose of the Study:

• To investigate the adherence properties of Lactobacillus crispatus JCM 5810 and Lactobacillus acidophilus JCM 1132 to mammalian extracellular matrix proteins.
• To identify the specific ECM components recognized by L. crispatus JCM 5810.
• To determine if the S-layer protein of L. crispatus JCM 5810 mediates this adherence.

Main Methods:

• Assessing bacterial adherence to immobilized ECM proteins (collagens, laminin, fibronectin) and Matrigel.
• Analyzing bacterial recognition of specific fibronectin fragments.
• Using radiolabeled collagen IV to quantify binding and inhibition assays with unlabeled ECM proteins.
• Extracting and purifying S-layer proteins for direct binding assays with collagen IV.

Main Results:

• L. crispatus JCM 5810 demonstrated significant adherence to type IV and I collagens, laminin, and fibronectin.
• L. acidophilus JCM 1132 showed no detectable adherence to these ECM components.
• The S-layer protein of L. crispatus JCM 5810 directly bound to type IV collagen.
• Adherence to collagen IV by the S-layer was inhibited by type I and IV collagens, but not by laminin or fibronectin.

Conclusions:

• L. crispatus JCM 5810 possesses an S-layer that mediates adherence to specific extracellular matrix proteins, particularly collagens.
• This collagen-binding S-layer facilitates the interaction of L. crispatus JCM 5810 with the human intestinal extracellular matrix.
• L. acidophilus JCM 1132 lacks these specific adherence capabilities via its S-layer.