Biological Comparator Inducible by IPTG and aTc
This part is composed from four composite parts: K101003, K101004, K101005, and K101006.
Control systems are an integral component of almost all aspects of life. Whether it is in industrial, biological, or chemical applications, controllers provide a way to keep systems functioning properly. A vital part of any control system is the comparator. This component compares a set point value and a measured value, and determines which is larger. It then sends the appropriate signal to the controller, which reacts to bring the system back to the set point. In typical applications, the controller equipment is electronic. However, our team set out to create a comparator using only genetic components. In order to undertake this task, a system involving six genes was designed. For our system, the two inputs (one representing the set point and one representing the measured value) are IPTG and ATC. These inputs will activate the transcription of the LacI and TetR proteins, and set in motion the rest of the system to produce the outputs. Depending on the amounts of the two inducer molecules added to the system, either green fluorescent protein (GFP) or red fluorescent protein(RFP) will be produced. This device was designed for use in the DH5alphaPro E.coli, in which TetR and LacI are constitutively produced. The comparator is a composite of four smaller parts, each composed of a promoter, RBS, gene, and terminator. This constitutive production creates the baseline state of the device, in which neither of the reporter genes (RFP and GFP) are expressed. Addition of IPTG and/or aTc to the system inhibits the repression of LacI and TetR and allows reporter expression to occur. Within the device are 4 individual composite parts. The first is the Lambda cI gene driven by the TetR promoter. This is followed by the p22 mnt protein which is driven by a LacI promoter. RFP expression is controlled by a TetR/p22 mnt dually repressed promoter, while GFP expression is controlled by a LacI/Lambda cI dually repressed promoter. Thus, when IPTG is present, only GFP should be expressed. Similarly, when aTc is present, only RFP should be expressed. It is this response that allows this device to function as a comparator.
One of the main considerations dealt with was the size of this part and whether it would be possible to successfully ligate a part of this size into an E.coli base vector. Most other considerations were dealt with during the design of the four smaller composite parts that this device is composed of.
RBS.3 (medium) -- derivative of BBa_0030
Weak1 RBS based on Ron Weiss thesis. Strength is considered relative to <bb_part>BBa_B0030</bb_part>, <bb_part>BBa_B0031</bb_part>, <bb_part>BBa_B0033</bb_part>.
Varies from -6 to +1 region from original sequence to accomodate BioBricks suffix ("RBS-2" in figure 4-14 of thesis). Contact info for this part: Brian Chow
Vinay S Mahajan, Voichita D. Marinescu, Brian Chow, Alexander D Wissner-Gross and Peter Carr IAP, 2003.
cI repressor from E. coli phage lambda (+LVA)
Elowitz, M. B. Transport, Assembly, and Dynamics in Systems of Interacting Proteins. Thesis, Princeton Univ., Princeton (1999).
Coding region for the cI repressor based on cI repressor from bacteriophage lambda modified with an LVA tail for rapid degradation of the protein. cI repressor binds to the cI regulator (BBa_R0051).
References (unparsed) here: A synthetic oscillatory network of transcriptional regulators , Elowitz M.B. , Leibler S., Nature(403),335-38: 2000 Octamerization of CI repressor is needed for effective repression of PRM and efficient switching from lysogeny. Ian B. Dodd,1 Alison J. Perkins, Daniel Tsemitsidis, and J. Barry Egan , Genes and Development (Vol 15, No. 22) 3013-3022: 2001 References (unparsed) here: A synthetic oscillatory network of transcriptional regulators , Elowitz M.B. , Leibler S., Nature(403),335-38: 2000 Octamerization of CI repressor is needed for effective repression of PRM and efficient switching from lysogeny. Ian B. Dodd,1 Alison J. Perkins, Daniel Tsemitsidis, and J. Barry Egan , Genes and Development (Vol 15, No. 22) 3013-3022: 2001 BBa_C0051 cI repressor is based on the cI repressor from the Elowitz's repressilator. It has been modified to include a rapid degradation LAA tail, and includes the BioBrick standard assembly head and tail restriction sites. The RBS has been removed. The stop codon has been changed from TAA to a double stop codon TAATAA.
Vinay S Mahajan, Brian Chow, Peter Carr, Voichita Marinescu and Alexander D. Wissner-Gross
Lutz, R., Bujard, H., Nucleic Acids Research (1997) 25, 1203-1210.
Sequence for pTet inverting regulator driven by the TetR protein.
BBa_R0040 TetR-Regulated Promoter is based on a cI promoter. It has been modified to include two TetR binding sites and the BioBrick standard assembly head and tail restriction sites.
June Rhee, Connie Tao, Ty Thomson, Louis Waldman
The Plac insert was PCR'd from the MG1655 strain of E.coli K12.
Inverting regulatory region controlled by LacI (<bb_part>BBa_C0010</bb_part>, <bb_part>BBa_C0011</bb_part>, etc.) The pLac regulatory region is a 243 base-pair sequence with standard BioBrick prefix and suffix sections on its ends. It contains two protein binding sites: CAP, which is generally present in E.coli and is assocciated with cell health and availability of glucose., and LacI, the Lac inhibitor <bb_part>BBa_C0010</bb_part> which binds in an dimerized cooperative manner to inhibit the transcription of the protein that follows. In the presence of lactose or IPTG, an analog of lactose, LacI is unable to correctly bind and inhibit transcription. This allows <bb_part>BBa_R0010</bb_part> to be used as a inverter or as a detector of lactose or IPTG.
LacI binds to this regulator. This part is incompatible with species containing active LacI coding regions. Lactose and IPTG disable the operation of LacI and this regulator. This part is incompatible with environments containing lactose or lactose analogs.
green fluorescent protein derived from jellyfish Aequeora victoria wild-type GFP (SwissProt: P42212
GFP (mut3b) [note that this part does not have a barcode]
mCherry from Roger Y. Tsien's lab, altered to be BioBrick compatible
mRFP (DsRed) derived, altered to be a biobrick by removing a PstI site and adding in the ends.
Made a point mutation to eliminate a PstI site in the middle and then added BioBrick ends using PCR. Sequenced using primers that bind to the pSB1A2 plasmid on either side of the brick.
Dual-Repressed Promoter for p22 mnt and TetR
This part was designed by combining sequences from parts C0040 (TetR promoter) and C0072 (p22 mnt promoter).
This part is a promoter that is repressed by both p22 mnt and TetR. It can be used to control the response of any gene that follows this promoter. It will be repressed by the presence of either p22 mnt or TetR.
TetR usually binds to two operator sites, one located upstream from -35 and one located between -35 and -10. However, p22 mnt also has two operator sites, one between -35 and -10 and another downstream from -10. Since each had an operator site in between -35 and -10, we had to eliminate the TetR operator site in order to allow the promoter to work. TetR was picked because it has a stronger binding than p22 mnt, and so would be more able to use only one site to bind.
mnt repressor (strong) from Salmonella phage P22 (+LVA)
wild type dimeric repressor from enterobacteriophage p22 with dissociation constant of 2.5*10^-12. sequence was translated with the E.Coli K12 codon usage table, and nucleotides 95-97 was changed from AAT to AAC to avoid the cut site GAATTC (94-99). Identification of Functionally Important Residues in the DNA Binding Region of the MNT Repressor Kendall, KL; Sauer, RT The Journal of Biological Chemistry, 264(23):13706-13710, 1989
Dual-Repressed Promoter for LacI and LambdacI
This part was made by combining BioBrick parts R0010(LacI promoter) and R0051 (LambdacI promoter), along with intermediate sequence between these operator sites.
This part is a new construct of a promoter that is dually repressed by either LacI or LambdacI proteins.
LambdacI usually binds to two operator sites, one located upstream from -35 and one located between -35 and -10. By itself, LacI binds downstream from -10. This made the part design very straightforward, since the locations of the operator sites do not overlap at all. In order to complete this part, we simply combined the proper sequences and we had a dually-repressed promoter.
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