Induction of transcripts encoding a novel seven-transmembrane protein during the hypersensitive response to tobacco mosaic virus infection in tobacco plants.

Immediate early responsive genes were screened by the differential display method during the hypersensitive response upon tobacco mosaic virus infection of tobacco ( Nicotiana tabacum L.) plants carrying the N gene. Three hours after temperature shift from 30 degrees C to 20 degrees C, an increase in transcripts of a particular clone was observed. The cDNA encoded a polypeptide of 330 amino acids, whose topology indicated it to be a seven-transmembrane protein, designated as Nt7TM1. This was confirmed by direct observation of cultured tobacco cells expressing an Nt7TM1-green fluorescent protein fusion protein, which migrated exclusively to the plasma membrane and the endoplasmic reticulum. RNA blot hybridization analysis indicated that Nt7TM1 transcripts were not induced by salicylic or jasmonic acids, ethylene or hydrogen peroxide. The results suggested the presence of a unique system for pathogen response involving a novel seven-transmembrane protein.