Plambda regulated luxR generator and Plux
This device produces luxR constitutively under the strong promoter Plambda, in absence of cI repressor. Plambda can be turned off by cI repressor and luxR production is inhibited. This composite part can be considered as 3OC6-HSL in -> PoPS out device, because 3OC6-HSL binds luxR which turns on Plux promoter. The output PoPS can also be regulated by cI repressor, which modulates luxR expression. Strong RBS (efficiency=0.6). Artificial 39 bp terminator (efficiency=0.99). {| |}
A synthetic oscillatory network of transcriptional regulators , Elowitz M.B. , Leibler S., Nature(403),335-38: 2000
The cI regulated promoter is based on the pR promtoer from bacteriohage lambda. The promoter has two two DNA binding sites for lambda cI repressor <bb_part>BBa_C0051</bb_part>. cI binding results in repression of transcription. The specific sequence used here is based on the cI repressible promoter used in the Elowitz repressilator (and references therein).
In order to address concerns about the promoter transcribing in the reverse direction, we have removed the -35 and -10 signals responsible for the promoter activity in the reverse direction. (More details needed here! DE, 2/24/03) Incompatible with host expressing cI repressor.
Vinay S Mahajan, Brian Chow, Peter Carr, Voichita Marinescu and Alexander D. Wissner-Gross
RBS.1 (strong) -- modified from R. Weiss
Strong RBS based on Ron Weiss thesis. Strength is considered relative to <bb_part>BBa_B0031</bb_part>, <bb_part>BBa_B0032</bb_part>, <bb_part>BBa_B0033</bb_part>.
Varies from -6 to +1 region from original sequence to accomodate BioBricks suffix ("orig" in figure 4-14 of Ron Weiss thesis). No secondary structures are formed in the given RBS region. Users should check for secondary structures induced in the RBS by upstream and downstream elements in the +50 to -50 region, as such structures will greatly affect the strength of the RBS. Contact info Brian Chow
Vinay S Mahajan, Voichita D. Marinescu, Brian Chow, Alexander D Wissner-Gross and Peter Carr IAP, 2003.
V. fischeri <genbank>AF170104</genbank>
In complex with HSL, LuxR binds to the Lux promoter, activating transcription from Pr <bb_part>BBa_R0062</bb_part>, and repressing transcription from Pl <bb_part>BBa_R0063</bb_part>. The lux cassette of V. fischeri contains a left and a right promoter. The right promoter gives weak constitutive expression of downstream genes.This expression is up-regulated by the action of the Lux activator, LuxR complexed to HSL. Two molecules of LuxR protein form a complex with two molecules the signalling compound homoserine lactone (HSL). This complex binds to a palindromic site on the promoter, increasing the rate of transcription.
2 silent point mutants were introduced in the coding sequence to remove internal XbaI and PstI sites. Mutation sites were chosen to replace codons commonly used in E. coli with codons used at a similar frequency.
Vinay S Mahajan, Voichita D. Marinescu, Brian Chow, Alexander D Wissner-Gross and Peter Carr
Promoter (luxR & HSL regulated -- lux pR)
Promoter activated by LuxR in concert with HSL The lux cassette of V. fischeri contains a left and a right promoter. The right promoter gives weak constitutive expression of downstream genes.This expression is up-regulated by the action of the LuxR activator protein complexed with the autoinducer, 3-oxo-hexanoyl-HSL. Two molecules of LuxR protein form a complex with two molecules of the signalling compound homoserine lactone (HSL). This complex binds to a palindromic site on the promoter, increasing the rate of transcription.
This promoter is based on the Vibrio fischeri quorum sensing gene promoters. Two genes LuxI and LuxR and transcribed in opposite directions as shown below. The original sequence from which the parts <bb_part>BBa_R0062</bb_part> and <bb_part>BBa_R0063</bb_part> were derived is shown in the picture below. <img src="<bb_file>Image1.gif</bb_file>" width="614" height="362">
modified E. coli thr terminator, replaced all A-T pairs in stem with C-G pairs
Artificial terminator, estimated %T~>90% *8bp stem, 6nt loop *Bidirectional, estimated reverse %T~>90%
Bidirectional, with the reverse estimated to be less effective than the forward. Has a polyA tail of 9 residues.
Conversion of the iGEM parts registry to SBOL2.1