Based on the following amino acid sequence below, what are all the possible DNA sequences that may have encoded this protein?

Based on the following amino acid sequence below, what are all the possible DNA sequences that may have encoded this protein? In order to do it, you must first determine what mRNA sequence would have encoded this protein and then convert that mRNA sequence to a DNA sequence. Be sure to label the 5' and 3' ends. 

Met - Lys - Phe - Arg - Cys - Pro