The Following Sequence of Four Amino Acids Occurred in the Structure

The following sequence of four amino acids occurred in the structure of a polypeptide found in a wild-type organism: Leu-Ser-Ile-Arg. Several mutants were isolated, each of which carried a single base pair change in the region of DNA that coded for this amino acid sequence. Their corresponding amino acid sequences are:
Mutant
1
MET-Ser-Ile-Arg
2
Leu-TRP-Ile-Arg
3
Leu-Ser-ARG-Arg
4
Leu-Ser-Ile-PRO
5
Leu-Ser-Ile-TRP
What was the nucleotide sequence of the region of mRNA that coded for the amino acid sequence in the wild-type organism? (Refer to Fig. 27-7)