Question

lex A is an E. coli gene whose product regulates thetranscription of certain target
genes that are located at different positions in the bacterialchromosome.
Identified target genes appear to be involved in DNA repair andrecombination.

Under normal conditions, the LexA protein binds near andrepresses
transcription of target genes; however, when the cell experiencessignificant
DNA damage caused by environmental mutagens, the LexA proteinis
inactivated and transcription of the target genes occurs.

Your research objective
is to identify all of the target genes repressed by the LexAprotein. (Assume that
you have access to a DNA microarray consisting of sequencesrepresenting each
of the genes in the E. coli genome.) As the starting point for yourwork, you
isolate a lexA mutant strain that produces no functional LexAprotein.

Briefly
describe an experiment that uses a functional genomics approach toidentify all
of the LexA target genes. Give the basic steps of the experimentand show how it
would allow you to achieve your objective.