Team:WITS-CSIR SA/Project/Concept
From 2011.igem.org
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<p>Firstly, we have chosen to use artificial riboswitches to control the expression of the flagella rotation regulator protein CheZ. To do this, we borrowed heavily from studies which have described riboswitch-controlled bacterial chemotaxis(Topps and Gallivan. 2007).Riboswitches are ligand-inducible RNA protein expression regulators that are comprised of an aptamer domain and an expression platform (Gallivan, 2007). The aptamer is a sequence of nucleotides that is designed to specifically bind to ligands, while the expression platform consists of a ribosome binding site (RBS) and a downstream coding region (CDS). When the specific ligand or analyte binds to the aptamer domain, the riboswitch undergoes a structural change. This results in the exposure of the RBS and the expression of the downstream CDS (Fig.2). Using this riboswitch mechanism, the expression of CheZ can be regulated in a ligand concentration-dependent manner, outside the control of the natural chemotaxis pathway (Fig2, bottom panel and right). Topps and Gallivan (2007) demonstrated that these riboswitches can be used to reprogram the chemotactic response of bacteria, so that they move up a concentration gradient, towards the source of the stimulus that activates the riboswitch (a process known aspseudotaxis). Bacteria can theoretically be reprogrammed to respond to any stimulus, if the appropriate riboswitch is made. This provides the versatility needed for biological network connections to be established in any application. Furthermore, this eliminates the need to engineer novel chemoreceptors.</p> | <p>Firstly, we have chosen to use artificial riboswitches to control the expression of the flagella rotation regulator protein CheZ. To do this, we borrowed heavily from studies which have described riboswitch-controlled bacterial chemotaxis(Topps and Gallivan. 2007).Riboswitches are ligand-inducible RNA protein expression regulators that are comprised of an aptamer domain and an expression platform (Gallivan, 2007). The aptamer is a sequence of nucleotides that is designed to specifically bind to ligands, while the expression platform consists of a ribosome binding site (RBS) and a downstream coding region (CDS). When the specific ligand or analyte binds to the aptamer domain, the riboswitch undergoes a structural change. This results in the exposure of the RBS and the expression of the downstream CDS (Fig.2). Using this riboswitch mechanism, the expression of CheZ can be regulated in a ligand concentration-dependent manner, outside the control of the natural chemotaxis pathway (Fig2, bottom panel and right). Topps and Gallivan (2007) demonstrated that these riboswitches can be used to reprogram the chemotactic response of bacteria, so that they move up a concentration gradient, towards the source of the stimulus that activates the riboswitch (a process known aspseudotaxis). Bacteria can theoretically be reprogrammed to respond to any stimulus, if the appropriate riboswitch is made. This provides the versatility needed for biological network connections to be established in any application. Furthermore, this eliminates the need to engineer novel chemoreceptors.</p> | ||
- | <img src="https://static.igem.org/mediawiki/2011/5/5c/Wits_Overview_Riboswitches_and_Gradient_circle.jpg" | + | <img src="https://static.igem.org/mediawiki/2011/5/5c/Wits_Overview_Riboswitches_and_Gradient_circle.jpg"> |
- | + | <p>Fig 2.Using ligand-responsive riboswitch activation of CheZ expression. CheZ can be fused to a reporter and direct bacterial motility in a ligand-dependent manner up a concentration gradient. </p> | |
</div> | </div> | ||
Revision as of 22:49, 19 September 2011
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The WITS_CSIR_SA iGEM 2011 team decided to create a microscopic biological communication network, in which there will be the transfer of data between bacterial populations as chemical signals. This type of system has been dubbed “Biotweet”. The generic framework of “Biotweet” may serve as the basis for the functioning of complex biological communication networks and may be useful in various applications, including those of the medical and industrial sectors.
Fig 1.The reprogramming of bacterial chemotactic response by using post-transcriptional activation of CheZ using a analyte-responsive riboswitch. CheZ expression results in counter-clockwise flagellar rotation and a “run and tumble” movement.
Firstly, we have chosen to use artificial riboswitches to control the expression of the flagella rotation regulator protein CheZ. To do this, we borrowed heavily from studies which have described riboswitch-controlled bacterial chemotaxis(Topps and Gallivan. 2007).Riboswitches are ligand-inducible RNA protein expression regulators that are comprised of an aptamer domain and an expression platform (Gallivan, 2007). The aptamer is a sequence of nucleotides that is designed to specifically bind to ligands, while the expression platform consists of a ribosome binding site (RBS) and a downstream coding region (CDS). When the specific ligand or analyte binds to the aptamer domain, the riboswitch undergoes a structural change. This results in the exposure of the RBS and the expression of the downstream CDS (Fig.2). Using this riboswitch mechanism, the expression of CheZ can be regulated in a ligand concentration-dependent manner, outside the control of the natural chemotaxis pathway (Fig2, bottom panel and right). Topps and Gallivan (2007) demonstrated that these riboswitches can be used to reprogram the chemotactic response of bacteria, so that they move up a concentration gradient, towards the source of the stimulus that activates the riboswitch (a process known aspseudotaxis). Bacteria can theoretically be reprogrammed to respond to any stimulus, if the appropriate riboswitch is made. This provides the versatility needed for biological network connections to be established in any application. Furthermore, this eliminates the need to engineer novel chemoreceptors.
Fig 2.Using ligand-responsive riboswitch activation of CheZ expression. CheZ can be fused to a reporter and direct bacterial motility in a ligand-dependent manner up a concentration gradient.
Gallivan JP. Toward reprogramming bacteria with small molecules and RNA. Curr Opin Chem Biol 2007;11:612-9
Topp S, Gallivan JP. Guiding bacteria with small molecules and RNA. J Am Chem Soc 2007;129:6807-11.