The chaperone GrpE mediates adhesion in Mycoplasma bovis and interactions with host extracellular matrix components and plasminogen

Mycoplasma bovis (M. bovis) is a significant pathogen responsible for various clinical manifestations in cattle, including pneumonia, mastitis, and arthritis. The challenges associated with managing M. bovis infections include the absence of specific therapeutic agents, increasing antibiotic resistance and the absence of an effective commercial vaccine. The chaperone GrpE is a crucial component of mycoplasma bacteria. However, because there are few tools for genetic manipulation of M. bovis, the role of GrpE in pathogenicity is yet unknown. In this study, GrpE was universally present in the tested M. bovis strains, and it was localized on the surface membrane. We first demonstrated that GrpE plays a vital role in the ability of M. bovis to adhere to embryonic bovine lung (EBL) cells in a dose-dependent manner. Importantly, the presence of anti-GrpE serum specifically inhibited this adhesion. Additionally, GrpE was shown to bind various components of the host extracellular matrix (ECM), such as fibronectin, collagen IV, laminin, and vitronectin. This interaction not only facilitated adhesion but also promoted the activation of plasminogen into plasmin via tissue plasminogen activator (tPA). The significance of GrpE was further underscored in that disruption of the grpE gene markedly reduced the adhesion of M. bovis to EBL cells, whereas this ability was restored in the complemented strain M. bovis ∆grpE:grpE. In conclusion, GrpE represents a novel adhesion protein in M. bovis that is crucial for its interaction with the host ECM and plasminogen. This research highlights the importance of GrpE in the pathogenicity of M. bovis and suggests that targeting this protein could offer new avenues for vaccine development and therapeutic strategies against M. bovis infections.