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 cellexperiences significant

DNA damage caused by environmental mutagens, the LexA proteinis

inactivated and transcription of the target genes occurs. Yourresearch 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 foryour work, you

isolate a lexA mutant strain that produces no functional LexAprotein.

a) Briefly describe an experiment that uses a functionalgenomics approach to identify all

of the LexA target genes.

b) Give the basic steps of the experiment and show how it

would allow you to achieve your objective