It is often challenging to predict the expression level of a gene from a promote

Question

It is often challenging to predict the expression level of a gene from a promoter. For instance, the expression level of a reporter protein is different from the same reporter fused to another protein. From the lecture, there are several methods developed to mitigate such issues.

A}What is the hypothesis that causes these irregular expression patterns?

B)Describe all 3 methods to address this problem.

C}Explain why the riboJ and Csy4 system will not work in mammalian cells

D)Even though these methods make the promoter activity more predictable, it doesn’t eliminate leakiness. You are tasked with using the riboswitch (genetic switch board by the Collins’ lab) discussed in class to minimize the leakiness. Using the Csy4 system, where (A, B, or C, see below) will you place the Csy4 cutting site and the cis repressor (CR) site and why? Please draw the csy4 and the CR site. The orientation is critical

Explanation / Answer

1)

The gene expression is depends on several factors, like promotor, enhancer, silencer sequences and transcriptional factors, etc. The positioning and absence or presence of these factors is also responsible for variation of chromosomal expression. The Promotor region and it is very essential for initiation of transcription. It contains sequences like “TATTA Box and CATTA Box, etc.”

For example, the change in the promoter sequence changes the gene expression pattern. The original (-35) promotor is –TTGACA and the changed promotor sequence is TGGACA, here a single T is replaced with G. The probability of occurrence of each nucleotide in the promoter is:

Hence, here a low probability nucleotide is replaced with high probability nucleotide. The change in this consensus sequence may be increase or decrease production of RNA (irregular expression patterns).

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