ADHERENCE, FIBRONECTIN-BINDING, AND INDUCTION OF CYTOSKELETON REORGANIZATION IN CULTURED HUMAN-CELLS BY MYCOPLASMA PENETRANS

Mycoplasma penetrans adhered to cultured human cells, forming clusters that localized to specific areas of the host cell surface, Adherence and cluster formation were inhibited by anti-M. penetrans antibodies, suggesting the involvement of specific adhesin receptor interactions, Ultrastructural studies showed that after 2 h of infection, mycoplasma s attach to and penetrate the host cell surface, M. penetrans bound se lectively to immobilized fibronectin, an interaction which was not inh ibited by a 70-kDa fragment containing a heparin-gelatin-binding domai n of fibronectin, other matrix glycoproteins, or an RGD tripeptide, su ggesting the recognition of other specific binding sites on the fibron ectin molecule, A ca. 65-kDa fibronectin-binding protein of M. penetra ns was eluted following Sepharose-fibronectin affinity chromatography. Confocal, light, and immunofluorescence microscopy demonstrated that the interaction of M. penetrans with target cells triggers a signal th at causes recruitment of several cytoskeletal components, including tu bulin and a-actinin, and aggregation of phosphorylated proteins. Deter gent-soluble mycoplasma proteins with apparent molecular masses of 18, 28, 32, 36, 39, and 41 kDa selectively bound to glutaraldehyde-fixed HEp-2 cells. Our findings offer new insights into understanding the in teraction of this human mycoplasma with host target cells.