November 7, 2010
BCMB 409/ Section 001
Professor: Tom Dockendorff
Bacteria: Communication Equals Modification
Bacteria are organisms that are extremely copious upon this planet. They are tiny and most are single celled organisms that can survive in just about any environment. Anywhere from plants to the human body is where these organisms can be discovered. Some of the strangest places that support bacterial life include places that have extremes of temperature. These bacteria are also very strange, much different from bacteria found living in and around humans. For example bacteria that live in extreme cold, like the North Pole, use methane as their substrates; and the ones that live in the deep sea use hydrogen sulphide. While most bacteria can live without oxygen (anaerobic bacteria) or whether they are aerobic bacteria that require oxygen. These particular bacteria use carbon-based sugars as main energy source. Even with so much diversity among bacteria, the most interesting part is how they communicate. Cell communication is a central mechanism in bacteria cells because it provides examples of parasitism relationship among different organisms such as S. aureus. It gives a means to control infections through a complex mechanism which is found in Pseudomonas aeruginosa. This touches on some variety of processes, including genetic transfer, antibiotic production growth and pathogenesis.
Many bacteria cells possess a unique communication system that allows them to exchange information within their own cell or among other cells. There have been recent studies about the communication among bacteria cells by using small molecules in order to communication with each other. These small molecules could consist of amino acid, peptide chains, or fatty acid derivatives. Moreover, these molecules aid the cells into exhibiting multi-cellular behaviors. The bacterium has the ability to sense diffusible signal molecules that are generated by other cells to modulate specific adaptive responses that enhance their survival rate. The ability of a signal bacterium to communicate among its neighbors, by using different mechanisms, creates a unified response that is essential for its survival and development.
One unique characteristic of cell-cell communication is the liberation of light by the organism. This process is known as bioluminescence, but the most studding aspect of the biochemical pathway is its regulation. Recent studies have explained how the actions of the ATP-dependent Lon protease of E. coli were involved with the downregluation of the Vibrio fischeri Lux operon. In addition, scientists have discovered that LuxR was a target Lon protease. Therefore, to show that this discovery was valid, they used a plasmid model to show the effects of Lon protease on V. fischeri LuxICDABEG expression. The use of Lux operon genes or DNA fragments encoding either full-length LuxR or its carboxyl-terminal end helped in this process. The more potent activator is the full-length LuxR protein than its carboxyl terminus. Up-regluation was seen at intracellular concentrations approximately two orders of magnitude lower than its carboxyl terminus. The regulatory mechanism has two aspects that work together in a synergistic manner.
The first aspect focus on how cells communicate to cells nearby that they exist, and each cell must decide if there are several cells present. This determination is carried out by a signal molecule that is formed by each cell and then ejected into the surrounding media. This signal molecule is dictated as an autoinducer. Secondly, the cellular machinery has to be able to receive the message. Once it is able to do this action, it will translate and act upon the message. Since the response from the cell gears towards the activation of the Lux operon, then this machinery must be a transcription factor interacting with the Lux operon.
The LuxR is an operon encoded...