You are interested in examining the regulation of the gene that encodes the enzy

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You are interested in examining the regulation of the gene that encodes the enzyme, Tre-ase, which is important in metabolizing trehalose in bacteria. Trehalose is a disaccharide that is formed from two glucose units. Interestingly, the Tre-ase enzyme is only expressed (i.e. the gene is transcribed and then translated) when glucose is unavailable to the bacteria but trehalose is present in the environment. 1. Given what you know about the Tre-ase gene (so far), would you consider the Tre-ase gene to be a regulated gene or a "housekeeping gene? Briefly, explain your answer 2. How does nutrition influence the expression of Tre-ase and why would transcriptional regulation of the Tre-ase gene protect the cell from wasting energy? Briefly, explain your answer. Hint: you will need to consider the role of signaling cascades and its role in modulating gene expression. There are two specialized transcription factors (TreA and TreB) that must bind to the promoter of the Tre-ase gene in order to regulate transcription of the Tre-ase gene. TreA binds to an "A" site in the promoter of the Tre-ase gene while TreB binds to the "B" site in the promoter. You make mutations in both of the TreA and TreB genes to create cells that lack these genes and then observe what happens to the transcription of the Tre-ase gene under different conditions (with or without glucose/trehalose). The results are shown below. Hint: try drawing out the pathway so that the results make sense. Transcription of Tre-ase in different media Glucose rehaloseGlucose+ normal cells lacking TreA cells lacking TreB cells lacking both TreA & TreB on OFF OFF OFF OFF on ON ON OFF OFF Trehalose OFF ON OFF OFF 3. What is the role of TreA in controlling Tre-ase expression? Explain. 4. What is the role of TreB in controlling Tre-ase expression? Explain. 5. From these data, what do you predict will happen to Tre-ase transcription (compared with that in normal cells) in the presence of trehalose if you were to create a version of the TreA protein that will constitutively bind to the "A" site in the Tre-ase promoter?

Explanation / Answer

1)Tre-ase gene responsible for the trehalose metabolism is regulatory gene.Because tre-ase gene control the exptression of regulatory protein which can promote and inhibit transcription.The regulatory protein binds to certain significant subunit to activate or silent the DNA transcription.

3)Roll of Tre A is repressor. when abscent in the presence of trehalose and presence of glucose/trehalose the operon always on

4)Roll of Tre B as repressor.-Whe it is present in the absence of glucose the transcription continues also in normal cell.Whe the Tre B is absent in the same condition the transcription is off.High level activation of operon is not possible.

5)Tre A is a repressor ands if theTre A protein is bound to A promoter site for long time the transcription of the trehalose is not possible.

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