In: Biology
Oh No! One of the tRNA genes in E.coli was mutated so that the wrong amino acid was charged onto it. Now, the amino acid that should be on the tRNA containing the anticodon 5'-CCA-3' is replaced with an Asp. DNA SEQUENCE: 5'-ATG TAG TTA TCC AAC CCT CCA AAA CAT GCA CCT CCT TAC TCA AGC AGG CAT ACG-3' a. Write out the protein sequence (using the DNA sequence from the problem above) that would be made in this situation. (3 pts) b. Does this mutation just affect this protein? What are the overall consequences of this type of mutation in e.coli? (3 pts)
Original DNA sequence:
5'-ATG TAG TTA TCC AAC CCT CCA AAA CAT GCA CCT CCT TAC TCA AGC AGG CAT ACG-3'
original protein sequence:
Met Stop L S N P P K H A P P Y S S R H T
now, when 5'-CCA-3' is changed to Asp or Aspertic acid which is coded by two codon , either GAT or GAC
when CCA is replaced with GAT or GAC the sequence will be like-
DNA sequence:
5'-ATG TAG TTA TCC AAC CCT GAT AAA CAT GCA CCT CCT TAC TCA AGC AGG CAT ACG-3
protein sequence:
Met Stop L S N P D K H A P P Y S S R H T
or 5'-ATG TAG TTA TCC AAC CCT GAC AAA CAT GCA CCT CCT TAC TCA AGC AGG CAT ACG-3
protein sequence:
Met Stop L S N P D K H A P P Y S S R H T
b) In this protein Proline group is changed to Aspertic acid. Generally whether a amino acid change within a polypeptide chain will effect just the protein of interest or other proteins is depends on the type of amino acid is changing. It also depends how the change in the amino acid will effect the protein size, shape or confirmation.As in this protein there is Methionine or start codon at the begenning, or protein translation is started , next comes the stop codon indicating end of the translation. Now, change in proline to Aspertic acid in this protein is not changing the protein sequence except the single amino acid. In both of the cases protein sequence has the stop codon after the start codon indicating end of translation. Thus there will be no effective consequene of this mutation in E.coli.