You Have Created a Piece of Recombinant DNA by Placing $\text { The Genetic Code }$

Essay

You have created a piece of recombinant DNA by placing a cDNA from a gene you believe is important for the differentiation of liver cells (called LC1) onto an expression plasmid that contains all the sequences necessary for propagation of this DNA in bacteria and for the production of the LC1 protein in bacteria.A picture of this plasmid is shown in Figure 10-66A, with the segment of the DNA containing the LC1 gene depicted as a gray rectangle; the promoter sequence is depicted as a white rectangle.The LC1 protein is phosphorylated on serine 54; the nucleotide sequence of the portion of the DNA that encodes this region is shown below the diagram.All HindIII and SalI restriction sites have also been mapped on the plasmid; the recognition sequences for these restriction nucleases are shown in Figure 10-66B. $\text { The Genetic Code }$
$\begin{array}{|l|l|l|l|l|}\hline & \text { U } & \text { C } & \text { A } & \text { G } \\\hline &\text { UUU Phe (F) } & \text { UCU Ser (S) } & \text { UAU Tyr (Y) } & \text { UGU Cys (C) } \\&\text { UUC - } & \text { UCC - } & \text { UAC - } & \text { UGC - } \\ \text { U } &\text { UUA Leu (L) } & \text { UCA -- } & \text { UAA Stop } & \text { UGA Stop } \\&\text { UUG - } & \text { UCG - } & \text { UAG Stop } & \text { UGG Trp (W) } \\\hline &\text { CUU Leu (L) } & \text { CCU Pro (P) } & \text { CAU His (H) } & \text { CGU Arg (R) } \\&\text { CUC - } & \text { CCC - } & \text { CAC - } & \text { CGC - } \\ \text { C}&\text { CUA - } & \text { CCA - } & \text { CAA Gin (Q) } & \text { CGA - } \\&\text { CUG }- & \text { CCG }- & \text { CAG }- & \text { CGG }- \\\hline &\text { AUU Ile (I) } & \text { ACU Thr (T) } & \text { AAU Asn (N) } & \text { AGU Ser (S) } \\&\text { AUC - } & \text { ACC - } & \text { AAC - } & \text { AGC - } \\ \text { A}&\text { AUA - } & \text { ACA - } & \text { AAA Lys (K) } & \text { AGA Arg (R) } \\&\text { AUG Met (M) } & \text { ACG - } & \text { AAG - } & \text { AGG - } \\\hline &\text { GUU Val (V) } & \text { GCU Ala (A) } & \text { GAU Asp (D) } & \text { GGU Gly (G) } \\&\text { GUC - } & \text { GCC - } & \text { GAC - } & \text { GGC - } \\ \text { G}&\text { GUA - } & \text { GCA - } & \text { GAA Glu (E) } & \text { GGA - } \\&\text { GUG - } & \text { GCG - } & \text { GAG - } & \text { GGG - } \\\hline\end{array}$
Table 10-56 (A)

(B)

Figure 10-66
A.Given the information above, write out the amino acids 52 to 57, encoded by the nucleotide sequence shown above.Be sure to number the amino acids appropriately.(Hint: Remember, serine is amino acid number 54.)
B.You want to create a mutant version of the LC1 gene that replaces the serine 54 found on this peptide with a glycine.You want to do this by changing only one nucleotide, and you also want to destroy the HindIII recognition sequence with this change.Write out a 21-nucleotide DNA sequence that can accommodate these changes.Be sure to (i) write out the DNA and label the 5′ and 3′ ends, (ii) underline the mutated HindIII recognition site, and (iii) circle any change made to the original sequence.