A MUTANT-CELL LINE RESISTANT TO VIBRIO-PARAHAEMOLYTICUS THERMOSTABLE DIRECT HEMOLYSIN (TDH) - ITS POTENTIAL IN IDENTIFICATION OF PUTATIVE RECEPTOR FOR TDH

Thermostable direct hemolysin (TDH), a pore-forming toxin produced by Vibrio parahaemolyticus, is cytotoxic to Rat-1, a fibroblast cell line derived from rat embryo. Through mutagenesis of Rat-1 with nitrosogua nidine, we established a mutant cell line, MR-T1. MR-T1 was over 200 t imes more resistant to the cytotoxic activity of TDH than Rat-1. TDH i ncreased membrane permeability of Rat-1 but not of MR-T1. Binding anal ysis showed that, while being able to bind to Rat-1, TDH failed to bin d to MR-T1, indicating that MR-T1 is deficient in the putative recepto r for TDH. Somatic hybrid cells between Rat-1 and MR-T1 were similarly sensitive to TDH as Rat-1. Moreover, TDH could bind to the hybrid cel ls as well as to Rat-1 cells. These results indicate that MR-T1 is pro mising for complementation cloning of a gene related to the putative r eceptor for TDH.