Question

refer to the table to answer the following question. which step is catalyzed by the enzyme encoded by the met 4 gene? methionine → homoserine, homocysteine → methionine, cystathionine → homocysteine, cysteine → cystathionine, homoserine → cysteine

Explanation:

The Met 4 gene - encoded enzyme catalyzes a step in the methionine synthesis pathway. By observing the growth of mutants on different media and the accumulation of compounds, we can determine the step. Met 4 mutant grows only when homocysteine or compounds downstream of it are provided. So, the enzyme encoded by Met 4 catalyzes the step from homocysteine to methionine.

Answer:

homocysteine → methionine