Molecular Biology Signaling Help!!! 3. You cross the Dig1 mutant with the Kss1 m

Question

Molecular Biology Signaling Help!!!

3. You cross the Dig1 mutant with the Kss1 mutant (the result is Dig1/Kss1 double mutant) and analyze the mating response. In this case, the new yeast strain shows a response about the same as the Dig1 single mutant. This shows that Kss1 operates upstream of Digi, Kss1 arrow Dig1. a. Based on this data and the information provided in table 1 - provide a mechanism that explains these results. b. Dig1 is known to bind to Ste12, based on the data from table 2, do you think that Dig1 is an inhibitor or an activator of Ste12? Explain c. If you were to develop a mutant in which Dig1 was non-functional (a delta Dig1 mutant), what do you predict the phenotype would be?

Explanation / Answer

SHOOMING; Shmooing is the process by which opposite mating type haploid yeast cells grow towards each other in order to fuse together to form a diploid (2n) cell. alpha-pheromone causes shmooing,

FUS1 ; Membrane protein localized to the shmoo tip; required for cell fusion; expression regulated by mating pheromone; proposed to coordinate signaling, fusion, and polarization events required for fusion; potential Cdc28p substrate

kss1 ; phosphorylates Dig 1 gene

Dig 1 act as a inhibitor of ste12

ste12 is required for mating and filamentation

ACCORDING TO TABLE;  

answer for a;

Kss1 can phosphorylate Dig1 and Dig2, two functionally redundant inhibitors of Ste12 , this shows that kss1 is operates upstream of Dig 1. kss 1 is a map kinases in yeast , where as fus3 gene act as inhibitor. when kss1 gene phosphorylates the Dig1 it cannot inhibhit the ste12 , which is responsible for mating and filamentation.

answer for b.;

Ste12 controls two distinct developmental programs of mating and filamentation. Ste12 activity is regulated by Fus3 and Kss1 MAP kinases through two Ste12 inhibitors, Dig1 and Dig2 . here in this case Dig 1 acting as an inhibitor.

answer for c;

if Dig 1 gene is non functional ,means it does not control ste12 gene which is responsible for mating ,so phenotype will be continous mating { shooming} occurs.

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