Question

Experiments by Charles Yanofsky in the 1950s and 1960s helped characterize the nature of tryptophan synthesis in E.coli. In one of Yanofsky's experiments, he identified glycine (gly) as the wild-type amino acid in position 211 of tryptophan synthetase, the product of the trpA gene. He identified two independent missense mutants with defective tryptophan synthetase at these positions that resulted from base-pair substitutions. One mutant encoded arginine (arg) and another encoded glutamic acid (glu). At position 235, wild-type tryptophan synthetase contains serine (ser), but a base-pair substitution mutant encodes leucine (leu). At position 243, the wild-type polypeptide contains glutamine, and a base-pair substitution mutant encodes a stop codon.

The most likely wild-type codon for position 235 is AGT/C. Identify the most likely wild-type codon(s) for position 235 and 243.

Answer 1

Charles yanofsky established gene sequence and protein sequences are collinear in bacteria. He explains changes in DNA sequence can capable to produce changes in protein sequence at corresponding positions of bacteria.

The most likely wild-type codon for position 235 is AGT/C

The most likely wild-type codon(s) for position 211 is GGA/G

The most likely wild-type codon(s) for position 235 is UCA/G

The most likely wild-type codon(s) for position 243 is CAA/G