Dhh1 and Dhh1 homologues (RCK/p54/DDX6) are members of the DEAD-box protein family of RNA helicases. These proteins display conserved sequence motifs for ATPase and RNA binding activities. Dhh1 is a… Click to show full abstract
Dhh1 and Dhh1 homologues (RCK/p54/DDX6) are members of the DEAD-box protein family of RNA helicases. These proteins display conserved sequence motifs for ATPase and RNA binding activities. Dhh1 is a component of the P-bodies (processing bodies) of mRNA granules and functions as an mRNA decapping activator in Saccharomyces cerevisiae. Dhh1 also contributes to gene-specific regulation during yeast mating. The dhh1 deletion mutation results in a significant decrease in the expression of Ste12, a mating-specific transcription factor, showing severe mating defects. Here, we introduced amino-acid substitution mutations in the ATPase and RNA binding domains of Dhh1 and also constructed a deletion of 79 amino acids at the Q/P-rich C-terminal region. The mutations in ATPase A and B motif (K96R, D195A) and C-terminus deletion showed reduced levels of mating efficiency as well as Ste12 protein expression. The Q/P-rich C-terminal region of Dhh1 was dispensable for growth at nonpermissive temperature 37°C but appeared to play an important role in regulating the Ste12 protein expression and mating processes. The P-body accumulation induced by treatment with α-mating factor required ATPase, RNA-binding and the Q/P-rich C-terminal domains of Dhh1.
               
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