Difference between revisions of "Promoters"

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[[Image:PromoterIconBC.png|thumb|right|400px|The regsitry symbol for a promoter is shown above a typical sequence for a bacterial promoter. The lavender shaded boxes indicate the two most conserved regions of a bacterial promoter and are located at -10 and -35 bases from the transcriptional start site (shaded in green). There are, on average, 17bp between the -10 and -35 sites and 7bp between the -10 site and the transcriptional start site.]]
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A promoter is a DNA sequence that tends to recruit transcriptional machinery and lead to transcription of the downstream DNA sequence.  The specific sequence of the promoter determines the binding affinity of the transcriptional machinery for the promoter and how likely the transcriptional machinery is to  initiate transcription after being recruited to the DNA.  A "strong" promoter is one that leads to a high rate of transcription initiation, while a "weak" promoter leads to a low rate of transcription initiation. 
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|align='center' width=80px | {{Click || image=RegistryList.png | link=Promoters/Catalog|width=50px | height=50px }}
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|align='center' width=80px |{{Click || image=Plasmidconstructionbutton.png | link=Promoters/Design |width=50px | height=50px }}
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|align='center' width=80px |{{Click || image=Plasmidhelpbutton.png | link=Help:Promoters |width=48px | height=48px }}
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| align='center' width=80px |'''[[Promoters/Catalog|Promoter catalog]]'''
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| align='center' width=80px |'''[[Promoters/Design|Promoter design]]'''
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| align='center' width=80px |'''[[Help:Promoters|Promoter help]]'''
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|}
  
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In addition to sequences that "promote" transcription, a promoter may include additional sequences known as operators that control the strength of the promoter.  For example, a promoter may include a binding site for a protein that either attracts or obstructs the transcriptional machinery from binding to the promoter.  The presence or absence of the protein will affect the strength of the promoter.  Such a promoter is known as a regulated promoter. 
 
  
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The registry has a large collection of promoters both unregulated and regulated.  Most of our promoters are designed to be recognized by ''E. coli'' RNA polymerase but we also have several promtoers that are recognized by T7 RNA polymerase and other RNA polymerase holoenzymes.
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{{:Promoters/Overview}}
  
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===An input/output description of promoter function===
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Sometimes, we ignore the details of how a promoter works and think of a promoter as a device that converts inputs into outputs.  You can do this when designing a multi-component system that includes promoters whose activity must be regulated by other species in the system.  A promoter can be thought of as a device that outputs a certain number of transcribing RNA polymerases per unit time.  Promoters can have different numbers of inputs.  A constitutive promoter has no inputs.  Technically, even a constitutive promoter has inputs, such as the level of free RNA polymerase, but we often assume that levels of free RNA polymerase are either unchanging, or never be the limiting factor in transcription initiation.  The level of a repressor that negatively regulates a promoter is an input to a promoter. 
  
 
==References==
 
==References==
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<biblio>
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*PMID 1093168
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#harley pmid=3550697
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*PMID 3550697
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#lisser1 pmid=8479900
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*PMID 8479900
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#lisser2 pmid=8055959
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*PMID 8055959
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</biblio>
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Latest revision as of 19:15, 12 June 2015

Promoter catalog Promoter design Promoter help


The registry symbol for a promoter is shown above a typical sequence for a bacterial promoter. The lavender shaded boxes indicate the two most conserved regions of a bacterial promoter and are located at -10 and -35 bases from the transcriptional start site (shaded in green). There are, on average, 17bp between the -10 and -35 sites and 7bp between the -10 site and the transcriptional start site pribnowharleylisser1lisser2.

A promoter is a DNA sequence that can recruit transcriptional machinery and lead to transcription of the downstream DNA sequence. The specific sequence of the promoter determines the strength of the promoter (a strong promoter leads to a high rate of transcription initiation).

In addition to sequences that "promote" transcription, a promoter may include additional sequences known as operators that control the strength of the promoter. For example, a promoter may include a binding site for a protein that attracts or obstructs the RNAP binding to the promoter. The presence or absence of the protein will affect the strength of the promoter. Such a promoter is known as a regulated promoter.

An input/output description of promoter function

Sometimes, we ignore the details of how a promoter works and think of a promoter as a device that converts inputs into outputs. You can do this when designing a multi-component system that includes promoters whose activity must be regulated by other species in the system. A promoter can be thought of as a device that outputs a certain number of transcribing RNA polymerases per unit time. Promoters can have different numbers of inputs. A constitutive promoter has no inputs. Technically, even a constitutive promoter has inputs, such as the level of free RNA polymerase, but we often assume that levels of free RNA polymerase are either unchanging, or never be the limiting factor in transcription initiation. The level of a repressor that negatively regulates a promoter is an input to a promoter.

References