Chapter 14, Problem 27P

This problem highlights some useful variations of the gene identification by plasmid transformation procedure shown in Fig. 14.28.

a.

Suppose you have obtained a new bacterial mutant strain with a phenotype of interest. To determine the affected gene, you sequence the entire genome of the mutant strain and compare it with that of a wild-type strain. One of the differences found is a nonsense mutation that seems to be a good candidate. How would you use a plasmid library to verify that this nonsense mutation is responsible for the mutant phenotype?

b.

Figure 14.28 showed how plasmid libraries could be used to identify genes with loss-of-function mutations that are responsible for a given aberrant phenotype. How could you use a plasmid library to identify a gene affected by a gain-of-function mutation?