CHE.496/2009/Schedule/Oral presentations of part design/Group 4: Difference between revisions
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====Stress responsive promoter==== | ====Stress responsive promoter==== | ||
'''Purpose''' | '''Purpose''' | ||
<p>This promoter would be able to turn on genes in response to the stringent response mechanism in bacteria.</p> | <p>This promoter would be able to turn on/off genes in response to the stringent response mechanism in bacteria.</p> | ||
'''Description''' | '''Description''' | ||
<p>[http://en.wikipedia.org/wiki/PpGpp ppGpp(p)] is an alarmone which gets produced in response to low levels of amino acids in the cell. Having a promoter responsive to this cellular signal would allow an engineered response certain types of stress on the cell. An example would be to put your synthetic metabolic network under control of a promoter that either gets directly inhibited by this signal or alternately, have such a promoter cause the production of an inhibitor for your synthetic genes.</p> | <p>[http://en.wikipedia.org/wiki/PpGpp ppGpp(p)] is an alarmone which gets produced in response to low levels of amino acids in the cell. Having a promoter responsive to this cellular signal would allow an engineered response certain types of stress on the cell. An example would be to put your synthetic metabolic network under control of a promoter that either gets directly inhibited by this signal or alternately, have such a promoter cause the production of an inhibitor for your synthetic genes.</p> | ||
'''Mechanism''' | '''Mechanism''' | ||
<p>ppGpp is produced by RelA and SpoT | <p>ppGpp is produced by RelA and SpoT <cite>Magnusson-2005</cite>. RelA is associated with ribosomes and is activated when an uncharged tRNA is in the A position. The precise triggers for SpoT is not known but it is activated in response to nutrient limitations including carbon starvation. ppGpp binds to RNA pol. and affects its translational targeting. It represses rRNA synthesis and also activates the rpoS gene, which codes for [http://en.wikipedia.org/wiki/Sigma_38 σ<sup>38</sup>]. Promoters responsive to this RNAP/σ<sup>38</sup> could be activated in response to stress/starvation. DksA conversely has been shown to positively regulate several promoters in response to stress. <cite>Magnusson-2007</cite></p> | ||
<p>Taking advantage of these cellular handles to have a feedback signal for an engineered metabolic network is useful, however these signals have many natural functions which may complicate their use as regulators. | <p>Taking advantage of these cellular handles to have a feedback signal for an engineered metabolic network is useful, however these signals have many natural functions which may complicate their use as regulators. <cite>Jishage</cite> Further, these promoters may be responsive to additional regulation that is useful for their natural use but may be undesirable in an engineered system.</p> | ||
'''Source & References''' | '''Source & References''' | ||
<biblio> | <biblio> | ||
# Magnusson-2005 [[doi:10.1016/j.tim.2005.03.008|Magnusson et al. (2005) Trends in Microbiology 13, 236]] | |||
# Magnusson-2007 pmid=17496080 | # Magnusson-2007 pmid=17496080 | ||
# Jishage pmid=12023304 | # Jishage pmid=12023304 | ||
Revision as of 11:25, 12 April 2009
Group 4
- Members: Dan Tarjan & George Washington
Parts
- Part 1
- Description
- Source & References
- Part 2
- Part 3
- Part 4
Stress responsive promoter
Purpose
This promoter would be able to turn on/off genes in response to the stringent response mechanism in bacteria.
Description
ppGpp(p) is an alarmone which gets produced in response to low levels of amino acids in the cell. Having a promoter responsive to this cellular signal would allow an engineered response certain types of stress on the cell. An example would be to put your synthetic metabolic network under control of a promoter that either gets directly inhibited by this signal or alternately, have such a promoter cause the production of an inhibitor for your synthetic genes.
Mechanism
ppGpp is produced by RelA and SpoT [1]. RelA is associated with ribosomes and is activated when an uncharged tRNA is in the A position. The precise triggers for SpoT is not known but it is activated in response to nutrient limitations including carbon starvation. ppGpp binds to RNA pol. and affects its translational targeting. It represses rRNA synthesis and also activates the rpoS gene, which codes for σ38. Promoters responsive to this RNAP/σ38 could be activated in response to stress/starvation. DksA conversely has been shown to positively regulate several promoters in response to stress. [2]
Taking advantage of these cellular handles to have a feedback signal for an engineered metabolic network is useful, however these signals have many natural functions which may complicate their use as regulators. [3] Further, these promoters may be responsive to additional regulation that is useful for their natural use but may be undesirable in an engineered system.
Source & References
- Magnusson LU, Gummesson B, Joksimović P, Farewell A, and Nyström T. Identical, independent, and opposing roles of ppGpp and DksA in Escherichia coli. J Bacteriol. 2007 Jul;189(14):5193-202. DOI:10.1128/JB.00330-07 |
- Jishage M, Kvint K, Shingler V, and Nyström T. Regulation of sigma factor competition by the alarmone ppGpp. Genes Dev. 2002 May 15;16(10):1260-70. DOI:10.1101/gad.227902 |
