Biology 401, Spring 2018 Problem Set 2 6. A few amino acids are post-translationally removed
from the C-terminal end of the beta- lactamase enzyme from B. imaginarium (i.e. - after it is
translated and released from the ribosome, a protease chews off a few amino acids). The wild-
type enzyme, which has had the amino acids removed from the C\'-terminus, is 327 amino acids
in length and the C-terminal amino acids are shown below aligned with the C-terminal amino
acids of a frameshift mutant, which is not processed at its C-terminus. The wildtype and
frameshift mutant have identical coding sequences except for the insertion or deletion of a single
nucleotide in the sequences encoding the C-terminal region of the protein. Use this information
to answer the questions below. A# 327 wild-type: Ser Asn Ala Lys Asp Trp mutant Ser Asn Ala
lle Arg Leu Asp Trp Gin Met Lys A What was the mutational event that gave rise to the
frameshift mutant? (identify which codon contains the inserted or deleted nucleotide and the
position within the codon where the mutation occurred. B. Deduce the number of amino acids in
the wild-type enzyme prior to processing of the C-terminus and, as far as possible, the actual
sequence of the C-terminus of the wild-type enzyme
Solution
A- There is the insertion of Uracil (U) in the codon AAA which makes the new codon as AUA
B- Codon in the wild-type would have been-
AAA GAU UGG AUU GGC AAA UGA AG
Amino acids - Lys- Asp-Trp-Ile-Gly-Lys Stop codon
So the number of amino acids before post-translational modification will be 330
from the C-terminal end of the beta- lactamase enzyme from B. imaginarium (i.e. - after it is
translated and released from the ribosome, a protease chews off a few amino acids). The wild-
type enzyme, which has had the amino acids removed from the C\'-terminus, is 327 amino acids
in length and the C-terminal amino acids are shown below aligned with the C-terminal amino
acids of a frameshift mutant, which is not processed at its C-terminus. The wildtype and
frameshift mutant have identical coding sequences except for the insertion or deletion of a single
nucleotide in the sequences encoding the C-terminal region of the protein. Use this information
to answer the questions below. A# 327 wild-type: Ser Asn Ala Lys Asp Trp mutant Ser Asn Ala
lle Arg Leu Asp Trp Gin Met Lys A What was the mutational event that gave rise to the
frameshift mutant? (identify which codon contains the inserted or deleted nucleotide and the
position within the codon where the mutation occurred. B. Deduce the number of amino acids in
the wild-type enzyme prior to processing of the C-terminus and, as far as possible, the actual
sequence of the C-terminus of the wild-type enzyme
Solution
A- There is the insertion of Uracil (U) in the codon AAA which makes the new codon as AUA
B- Codon in the wild-type would have been-
AAA GAU UGG AUU GGC AAA UGA AG
Amino acids - Lys- Asp-Trp-Ile-Gly-Lys Stop codon
So the number of amino acids before post-translational modification will be 330
