Difference between revisions of "Help:Regulatory"

Revision as of 14:22, 11 July 2006

Regulatory parts (also known as 'promoters') are those which provide binding regions for RNA polymerase, the enzyme which performs the act of transcription (the conversion of DNA to RNA).

E.coli's RNA polymerase is a large enzyme which spans about 6 turns of a DNA helix, which is equivalent to about 60 base pairs. Thus many promoter regions for e.coli are approximately 60 bp in length.

Some sub-categories of Regulatory parts are:

Control

This describes whether the default state of the regulatory region is normally in the 'on' (repressible) or 'off' (inducible) state of transcription. Note that "normally" denotes a system in a static state with no inputs provided (ie. if this were the only Biobrick to exist on the only plasmid in a cell strain).
More details on each of those two categories below.

Please note that ligands associated with specific cell strains may cause changes in the control behaviour of the part. These changes should be noted on the regulatory parts or cell strain page.

Repressible

Regulatory regions which allow for continual high-level transcription of DNA. Often these parts can be down-regulated (transcription downregulated) by the addition of ligand. The use of constituitive promoters can be desirable since they are less susceptible to cross-talk and can hypothetically take in PoPS input.

Examples of repressible parts include

Part:BBa_R0040 - the pTet promoter region, controlled by tetracycline or its chemical analog [http://openwetware.org/wiki/ATc ATC]

Part:BBa_R0011 - the pLac promoter region, controlled by the lactose protein or by its chemical analog [http://openwetware.org/wiki/IPTG IPTG]

Inducible parts

Parts which are continually "off" (at low DNA transcription levels), but allow for activation (increased transcription) through the addition of particular ligands

Examples include:

Part:BBa_R0080 - The araC promoter region, which can be activated by the addition of the sugar [http://openwetware.org/wiki/Arabinose arabinose]

Part:BBa_I0500 - Another [http://openwetware.org/wiki/Arabinose arabinose] inducible promoter region

Other parts

These are parts which can be both upregulated and downregulated in their normal state by

Direction

A regulatory region can point RNA polymerase in either the forward or reverse directions depending on which strand of the double stranded DNA molecule it decides to bind to. Currently most Biobrick regulatory parts transcribe DNA in the forward direction.

References

Ptashne, Mark. "A Genetic Switch". Cold Spring Harbor Press, 1986.

@@ Line 13: / Line 13: @@
 More details on each of those two categories below.<br>
-Please note that ligands associated with specific cell strains may cause changes in the control behaviour of the part.  These changes should be noted on the [[Transcriptional Regulators|regulatory parts]] or [[Cell Strains|cell strain page]].  <br>
+Please note that ligands associated with specific cell strains may cause changes in the control behaviour of the part.  These changes should be noted on the [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=Regulatory regulatory parts] or [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=cell cell strain page].  <br>
 ===Repressible===