GENETIC-ANALYSIS OF MUTATION INTERACTION IN 2 GENES-CONTROLLING THE EXPRESSION OF MDG4

Transcription of the retrovirus-like mobile element mdg4 (gypsy) in co ntrolled by the protein product of the supressor of Hairy wing which i nteracts with the mdg4 enhancer, and by the protein product of the mdg 4 modifier which seems to interact with the su(Hw) protein. In the pre sent work, we studied interaction of mod(mdg4) and su(Hw) mutations in phenotypic expression of mutations induced by mdg4 insertion. Differe nt types of inhibitory effect of mdg4 enhancer on transcription of the targer gene were detected. Most frequently, the inhibitory depends on the presense of the mod(mdg4) protein. On of the two acidic domains o f su(Hw) protein may be removed without changing the effect. Additiona l removal of the leucine zipper domain strongly reduces the effect. Th e second type of inhibition depends of removal of or decrease in the c oncentration of the mod(mdg4) protein. The su(Hw) protein should have both acidic domains in this case. Sometimes, the su(Hw) protein lackin g theC-end acidic domain may activate transcription of a target gene, and this effect does not depend on the presence or absence of the mod( mdg4) protein. The effect may be increased by removal of leucine zippe r. Binding of the mod(mdg4) protein to the su(Hw) protein does not dep end of the C-end acidic domain and leucine zipper.