Your main post must be at least 150 words. It should include citations and references to support your conclusions.

For this discussion you characterize a transcriptional regulatory system like the ones just described. However, for our purposes this should be entirely fictional. You can even invent your own bacterial species!!

In your initial discussion board post, please include the following:

1. Make up an operon, the regulatory proteins, the cellular process and the molecules being “sensed”.

2. Describe your fictional operon with legitimate details about the orientation of the genes and the promoter/operator sequences or activator binding site.

3. Provide details about the repressor/activator and inducer/inhibitor proteins.

4. Explain how the operon helps your pathogen survive and possibly thrive in its host.

5. Include details about conditions that trigger expression of the gene(s).

Gene expression is regulated at many levels in bacteria. Figure 14.1 in your textbook displays a summary of regulatory mechanisms used to control gene expression. The expression of bacterial genes is controlled by the action of diffusible repressors and activators. Tetracycline is an antibiotic used to treat respiratory infections, infections of the skin, including acne, and infections of the genitourinary system. Over time however, many bacteria have become resistant to tetracycline. The mechanism often utilized by resistant strains is the synthesis and use of an efflux pump. While there are multiple types, in general, this pump consists of a membrane‐spanning protein that extrudes the antibiotic from the cell. Since efflux pumps are energetically expensive to make, they are only produced when tetracycline is present. A repressor protein, TetR, has been identified and characterized in resistant strains. The efflux‐pump is negatively controlled by TetR. TetR binds to the operator region when there is no tetracycline available. When tetracycline is present, TetR is released from the DNA. TetR gene transcription is inhibited by the repressor protein. We can also look at an example of positive control. Regulatory proteins can bind to activator binding sites in the presence of a key nutrient or other chemical in the cell. The cell is “sensing” the presence of this nutrient and theactivator can then turn on genes in response. This is the case with the transcription of fimbriae genes in some pathogens. In order to conserve resources, fimbrial genes are only transcribed when the pathogen is in the nutrient rich environment of the host where the amino acid leucine is abundant. Under these conditions, the pathogen develops fimbriae and attaches itself to the epithelium of the host.

This is an example of what I need done: nothing big

Prompts:

Make up an operon, the regulatory proteins, the cellular process and the molecules being “sensed”.Describe your fictional operon with legitimate details about the orientation of the genes and the promoter/operator sequences or activator binding site.Provide details about the repressor/activator and inducer/inhibitor proteins.Explain how the operon helps your pathogen survive and possibly thrive in its host.Include details about conditions that trigger expression of the gene(s).

Response:

Pokrastinatn has 4 operons. This operon uses an enhancer as well as a corepressor to work its magic.

The enhancer attaches itself to the CRP protein causing an increase in its production. When this protein is in high quantities it causes a large amount of fatigue to occur, making naps more prevalent throughout the day. While this enhancer is causing you to become more tired, a corepressor is creating its own mess.

This corepressor binds itself to the transcription factor for the gene for focus. By doing this, it inhibits the production of this gene causing you to lose focus on the task at hand. With this gene repressed the subject finds themselves easily distracted and prone to put things off.

Pokrastinatn is able to excel in its host in a couple of different ways. The first is with the increase in fatigue the host is almost always to tired or lazy to do anything about his condition. The second is with the repressed gene for focus, even when the host isn’t as fatigued he is easily distracted and always says that he will get it checked “tomorrow”.

Conditions that trigger this condition are an increase in tasks that need to be completed, being nagged by your significant other, and shiny objects.

References:

Biol Psychiatry, Nov 1 2009, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763037/

Prescott's Microbiology Avenue of the Americas : Ninth Ed; New York ; 2014.