User:Miaomin Zhang/Sandbox 1
From Proteopedia
(New page: Bacterial chemotaxis receptor One of the CBI Molecules being studied in the [http://www.umass.edu/cbi/ University of Massachusetts Amherst Ch...) |
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| - | [[Image:intactModelLargeText.jpg|frame|Bacterial chemotaxis receptor]] | ||
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One of the [[CBI Molecules]] being studied in the [http://www.umass.edu/cbi/ University of Massachusetts Amherst Chemistry-Biology Interface Program] at UMass Amherst and on display at the [http://www.molecularplayground.org/ Molecular Playground]. | One of the [[CBI Molecules]] being studied in the [http://www.umass.edu/cbi/ University of Massachusetts Amherst Chemistry-Biology Interface Program] at UMass Amherst and on display at the [http://www.molecularplayground.org/ Molecular Playground]. | ||
| - | Many bacteria can "smell" their surroundings and "choose" where to go. They detect molecules such as amino acids or sugars using receptors that bind these molecules and transmit a signal into the cell. This signal controls several proteins which ultimately control the direction of rotation of the motors that rotate the flagella. One direction causes the cell to continue swimming; the other direction causes the cell to tumble. When an attractant molecule binds, the receptor signals: "Things look good, keep swimming!" The opposite signal occurs when bacteria sense a repellant or less attractant molecules: "Time to tumble and try a new swimming direction." | ||
| + | === S-adenosylmethionine-dependent protein methyltransferase, CheR === | ||
| - | + | Molecular Playground Banner: CheR, the protein that reactivates numb bacterial "noses" | |
| - | {{Clear}} | ||
| - | <applet load='1wat' size='[450,338]' frame='true' align='right' | ||
| - | caption='Aspartate receptor ligand binding domain (1wat)' scene='User:Lynmarie_K_Thompson/Sandbox_1/Loadedfrompdb/4'/> | ||
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| - | === Ligand-binding domain === | ||
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| - | The spinning protein (<scene name='User:Lynmarie_K_Thompson/Sandbox_1/Loadedfrompdb/4'>Initial view</scene>) ) is the ligand binding domain of the aspartate receptor with the aspartate ligand bound (LKT). | ||
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| - | Molecular Playground banner: A bacterial chemotaxis receptor protein used by bacteria to "smell" their environment. | ||
| + | Bacteria such as Salmonella typhimurium use chemotaxis system to swim towards neutrients and other attractants. At the forefront of the chemotaxis system are a set of transmembrane proteins called chemoreceptors. They sense the chemical environment and trigger the chemotaxis signal transduction pathway, which eventually affect the flagella motors, causing bacteria to either keep moving up the gradient (if they are on the right track) or stumble to change directions. However, the binding between attractants and chemoreceptors also suppresses the receptor activity and reduces the tumbling frequency. An adaptation mechanism is therefore needed to restore chemoreceptors' activity to elicit flagella responses. This is provided by reversible methylation of specific glutamate residues in the chemoreceptors' cytoplasmic domains, where methylation is catalyzed by S-adenosylmethionine-dependent protein methyltransferase, CheR. | ||
{{Clear}} | {{Clear}} | ||
| - | <applet load=' | + | <applet load='1bc5' size='[450,338]' frame='true' align='right' |
| - | caption=' | + | caption='S. typhimurium CheR (1bc5)' scene='User:Miaomin_Zhang/Sandbox_1/Revolutionary_conservation/7'/> |
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| - | CheW is a chemotaxis adaptor protein, and part of the tertiary complex formed by the chemotaxis receptor, histidine kinase protein CheA, and CheW. As an adaptor protein, CheW mediates the interaction between the chemotaxis receptor and CheA, and is necessary for the formation of kinase active complexes. CheW has been found to bind to the P5 domain of CheA through crystallographic studies. | ||
| - | + | CheR binds to a specific sequence at the C-termini of chemoreceptors through noncovalent interactions like hydrogen bonds and methylates neighboring receptor molecules. The <scene name='User:Miaomin_Zhang/Sandbox_1/Revolutionary_conservation/7'>3D structure</scene> on the right shows the S. typhimurium CheR protein in revolutionary conservation grade colors [[http://proteopedia.org/wiki/index.php/Conservation%2C_Evolutionary]]. The green chain represents the C-terminal pentapeptide of the aspartate receptor (Tar) to which CheR is attached; and the methylation reaction product, S-adenosylhomocysteine (AdoHcy) that lies at center of CheR is shown in ball-and-stick model and CPK element colors. As seen from this scene, the active site of CheR is the most highly conserved part of the protein. | |
Current revision
One of the CBI Molecules being studied in the University of Massachusetts Amherst Chemistry-Biology Interface Program at UMass Amherst and on display at the Molecular Playground.
S-adenosylmethionine-dependent protein methyltransferase, CheR
Molecular Playground Banner: CheR, the protein that reactivates numb bacterial "noses"
Bacteria such as Salmonella typhimurium use chemotaxis system to swim towards neutrients and other attractants. At the forefront of the chemotaxis system are a set of transmembrane proteins called chemoreceptors. They sense the chemical environment and trigger the chemotaxis signal transduction pathway, which eventually affect the flagella motors, causing bacteria to either keep moving up the gradient (if they are on the right track) or stumble to change directions. However, the binding between attractants and chemoreceptors also suppresses the receptor activity and reduces the tumbling frequency. An adaptation mechanism is therefore needed to restore chemoreceptors' activity to elicit flagella responses. This is provided by reversible methylation of specific glutamate residues in the chemoreceptors' cytoplasmic domains, where methylation is catalyzed by S-adenosylmethionine-dependent protein methyltransferase, CheR.
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CheR binds to a specific sequence at the C-termini of chemoreceptors through noncovalent interactions like hydrogen bonds and methylates neighboring receptor molecules. The on the right shows the S. typhimurium CheR protein in revolutionary conservation grade colors [[1]]. The green chain represents the C-terminal pentapeptide of the aspartate receptor (Tar) to which CheR is attached; and the methylation reaction product, S-adenosylhomocysteine (AdoHcy) that lies at center of CheR is shown in ball-and-stick model and CPK element colors. As seen from this scene, the active site of CheR is the most highly conserved part of the protein.
