FISSION YEAST REP2 IS A PUTATIVE TRANSCRIPTIONAL ACTIVATOR SUBUNIT FOR THE CELL-CYCLE START FUNCTION OF RES2-CDC1O

In the yeast cell cycle 'start' requires sets of the Cdc10/ SWI family of transcriptional factors which activate the MCB cis elements contai ned in genes essential for S phase progression. Fission yeast possess two such overlapping systems, Res1-Cdc10 and Res2-Cdc10, both of which act to start the mitotic and meiotic cycles, We have recently isolate d rep2(+) as a multicopy suppressor of a temperature-sensitive cdc10 m utant which encodes a zinc finger protein. Here we show that the Rep2 zinc finger protein is an essential component of the active Res2-Cdc10 transcriptional regulator complex and likely to play a role in the co ntrol of cell cycle 'start'. Our data suggest that Rep2 is a transcrip tional activator subunit which interacts with the MCB binding subunit complex formed by Res2 and Cdc10.