GENETIC INTERACTION OF DED1 ENCODING A PUTATIVE ATP-DEPENDENT RNA HELICASE WITH SRM1 ENCODING A MAMMALIAN RCC1 HOMOLOG IN SACCHAROMYCES-CEREVISIAE

The Saccharomyces cerevisiae temperature-sensitive mutants srm1-1, mtr 1-2 and prp20-1 carry alleles of a gene encoding a homolog of mammalia n RCC1. In order to identify a protein interacting with RCC1, a series of suppressors of the srm1-1 mutation were isolated as cold-sensitive mutants and one of the mutants, designated ded1-21, was found to be d efective in the DEDI gene. The double mutant, srm1-1 ded1-21, could gr ow at 35 degrees C, but not at 37 degrees C. A revertant of srm1-1 ded 1-21 that became able to grow at 37 degrees C acquired another mutatio n in the SRM1 gene, indicating the tight relationship between SRM1 and DED1. In all the rcc1(-) strains examined, the amount of mutated SRM1 proteins was reduced or not detectable at the nonpermissive temperatu re. While mutated SRM1 protein was stabilized in all of the rcc1(-) st rains by the ded1-21 mutation, the ded1-21 mutation suppressed both sr m1-1 and mtr1-2, but not the prp20-1 mutation, contrary to the previou s finding that overproduction of the S. cerevisiae Ran homolog GSP1 su ppresses prp20-1, but not srm1-1 or mtr1-2.