After several rounds of experiments like those described above, you find that you have identified five different genes involved in the biosynthesis of tryptophan in this organism. You name them Gene 1 through Gene 5. Based on your knowledge of the pathway of tryptophan biosynthesis from Problem Set 2, you set out to compare this with the pathway in your new yeast species.
The figure below shows the pathway of tryptophan in most organisms.
You try growing a representative mutant from each complementation group (gene) on medium containing various intermediates in the tryptophan biosynthetic pathway and summarize your results in the table below. The symbol "+" indicates that a mutant in that gene grew when provided with only that compound in minimal medium. The symbol "-" indicates no growth under those conditions.
Compound Gene 1 Gene 2 Gene 3 Gene 4 Gene 5
Shikimate - - - - -
Shikimate-3-P - - - - -
Carboxyvinyl-3-P-shikimate - - - - -
Chorismate - - - - -
Anthranilate - - - + -
Phosphoribosyl anthranilate - - - + +
Carboxyphenylamino deoxyribulose-5P - + - + +
Indoleglycerol-P + + - + +
Indole + + - + +
Tryptophan + + + + +
Based on these data and the pathway shown above, give the most likely name of the enzyme encoded by each gene (when grading your answer, we will ignore capitalization, spaces, and dashes):
Gene 1
unanswered
Gene 2
unanswered
Gene 3
unanswered
Gene 4
unanswered
Gene 5
Gene 1: Phosphoribosyl anthranilate isomerase
Gene 2: Carboxyphenylamino deoxyribulose-5P synthase
Gene 3: Phosphoribosyl anthranilate transferase
Gene 4: Indole-3-glycerol phosphate synthase
Gene 5: Tryptophan synthase
To determine the most likely name of the enzyme encoded by each gene, we can analyze the growth patterns of the mutants in the presence of different compounds in the tryptophan biosynthetic pathway.
Looking at the table, we can see that mutants lacking Gene 1, Gene 2, Gene 3, and Gene 4 are unable to grow when provided with any of the compounds in the pathway. This suggests that these genes are involved in early steps of the pathway, before the production of any compound shown in the table.
Gene 5, on the other hand, allows mutants to grow when provided with all compounds in the pathway except for Shikimate, Shikimate-3-P, Carboxyvinyl-3-P-shikimate, and Chorismate. This indicates that Gene 5 is likely involved in the conversion of one of these compounds to the next intermediate in the pathway.
By process of elimination, we can deduce the most likely names of the enzymes encoded by each gene:
Gene 1: Enzyme involved in the conversion of an early compound (before Shikimate).
Gene 2: Enzyme involved in the conversion of Shikimate to Carboxyphenylamino deoxyribulose-5P.
Gene 3: Enzyme involved in the conversion of Carboxyphenylamino deoxyribulose-5P to Indoleglycerol-P.
Gene 4: Enzyme involved in the conversion of Indoleglycerol-P to Indole.
Gene 5: Enzyme involved in the conversion of Anthranilate to Phosphoribosyl anthranilate.
Please note that the specific names of these enzymes cannot be determined solely based on the information provided. Additional biochemical and genetic studies would be required for a more accurate identification.