This composite part was obtained assembling existing Bioparts at the registry.
The expression of the trp operon is repressed 300-fold by TrpR. TrpR binds at the trpLp promoter, possibly directly blocking binding by RNA polymerase Klig LS,1988. The blue light sensor LovTAP is a chiameric protein that contains the TrpR DNA-binding domain, so that is expected to regulate trpL promoter as the native TrpR transcriptional regulator.
Claudia Ivonne Hernandez Armenta, Jorge Zepeda
LovTAP was assembled by Strickland et al. Reference Strickland, D., Moffat, K., & Sosnick, T. (2008). Light-activated DNA binding in a designed allosteric protein. Proceedings of the National Academy of Sciences, 105(31), 10709. National Acad Sciences. Retrieved from http://www.pnas.org/content/105/31/10709.full.
LovTAP This photoreceptor was assembled by Strickland et al., and consists of a LOV (light-oxygen-voltage) domain of Avena sativa phototropin1 (AsLOV2) that senses blue light, fused to the trpR- DNA binding domain of the transcription factor trp repressor. The resulting protein is called LovTAP: LOV- and tryptophan-activated protein. LOV domains bind a flavin-mononucleotide (FMN) or flavin-adenine-dinucleotide (FAD) cofactor, which are used in a wide variety of metabolic pathways as cofactors in redox reactions and are available in most organisms. The cofactor has a broad absorption spectrum, with a maximum at 450 nm. Besides, the core of the LOV domain is often flanked by amino- or carboxy-terminal helices, termed A???α and Jα, respectively. In the LovTAP construction, AsLOV2 domain via its carboxyl-terminal Jα ???helix was ligated to an amino-terminal truncation of TrpR. The resulting protein has a domain-domain overlap with a shared helix. Thus, photoexcitation would change the conformation of the protein, in turn changing the stability of the shared-helix-domain contacts. Under the presence of light, absorption of a photon leads to the formation of a covalent adduct between the flavin mononucleotide (FMN) cofactor and a conserved cysteine residue in the AsLOV2 domain, which results in conformational rearrangements in LovTAP. This change impacts the affinity of the shared helix for the two domains: disrupting the contacts between the shared helix and the LOV domain and enabling the association of the shared helix with the TrpR domain, which establishes DNA-binding affinity and LovTAP can then bind DNA as an homodimer, repressing the transcription of the genes downstream of its binding sites. In the dark, when the shared helix contacts the LOV domain, the TrpR domain's DNA-binding affinity decreases and LovTAP is in an inactive conformation.
We decided to synthesize a new LovTap part, that in comparison with the Part:BBa_K191006[1] that is already at the registry, has the following differences: 1. The 2 '''PstI restriction sites''' were '''removed''' from the coding region of LovTap. 2. We included a punctual mutation to change the '''ILE427 by a PHE427''', as was proposed by the model results of the team iGEM09_EPF-Lausanne [2]. With this mutation LovTAP should react faster and the conformational change should be more stable (the protein stays in the active form for longer, under light induction). The reason of the conformational change is the following: Cys450 side chain is involved in light state in bond formation with the cofactor. Cys450 can assume two conformational states, called here ON and OFF, and corresponding respectively, to the Sg being near or far from FMN[2]. The isoleucine 427 is quite big. But not enough to push the cystein's side chain significantly toward the cofactor. So we choose to replace this ILE427 by an PHE427, an amino acid which is much bigger and have more or less the same propreties than the ILE[2]. 5. The stop codon tga was changed for two taa. 1. Registry entry: Part:BBa_K191003 2. Wiki Team: EPF-Laussane. Simulations and results of predicted lovTAP mutations. 3. Wiki Team: EPF-Laussane. LovTAP characterization results. 4. Registry entry: Part:BBa_B0030 5. Registry entry: Part:BBa_B0032 6. Registry entry: Part:BBa_R0010
LovTAP was assembled in the following article: Strickland, D., Moffat, K., and Sosnick, T. (2008). Light-activated DNA binding in a designed allosteric protein. Proceedings of the National Academy of Sciences, 105(31), 10709. National Acad Sciences. Retrieved from http://www.pnas.org/content/105/31/10709.full.
This photoreceptor was assembled by Strickland et al., and consists of a LOV (light-oxygen-voltage) domain of Avena sativa phototropin1 (AsLOV2)that senses blue light, fused to the trpR- DNA binding domain of the transcription factor trp repressor. The resulting protein is called LovTAP: LOV- and tryptophan-activated protein. LOV domains bind a flavin-mononucleotide (FMN) or flavin-adenine-dinucleotide (FAD) cofactor, which are used in a wide variety of metabolic pathways as cofactors in redox reactions and are available in most organisms. The cofactor has a broad absorption spectrum, with a maximum at 450 nm. Besides, the core of the LOV domain is often flanked by amino- or carboxy-terminal helices, termed Aa and Ja, respectively. In the LovTAP construction, AsLOV2 domain via its carboxyl-terminal Ja ???helix was ligated to an amino-terminal truncation of TrpR. The resulting protein has a domain-domain overlap with a shared helix. Thus, photoexcitation would change the conformation of the protein, in turn changing the stability of the shared-helix-domain contacts. Under the presence of light, absorption of a photon leads to the formation of a covalent adduct between the flavin mononucleotide (FMN) cofactor and a conserved cysteine residue in the AsLOV2 domain, which results in conformational rearrangements in LovTAP. This change impacts the affinity of the shared helix for the two domains: disrupting the contacts between the shared helix and the LOV domain and enabling the association of the shared helix with the TrpR domain, which establishes DNA-binding affinity and LovTAP can then bind DNA as an homodimer,repressing the transcription of the genes downstream of its binding sites. In the dark, when the shared helix contacts the LOV domain,the TrpR domain's DNA-binding affinity decreases and LovTAP is in an inactive conformation.
We decided to synthesize a new LovTap part, that in comparison with the Part:BBa_K191006 [1] that is already at the registry, has the following differences: 1.The 2 PstI restriction sites were removed from the coding region of LovTap. 2.We included a punctual mutation to change the ILE427 by a PHE427, as was proposed by the model results of the team iGEM09_EPF-Lausanne [2]. With this mutation LovTAP should react faster and the conformational change should be more stable (the protein stays in the active form for longer, under light induction). The reason of the conformational change is the following: Cys450 side chain is involved in light state in bond formation with the cofactor. Cys450 can assume two conformational states, called here ON and OFF, and corresponding respectively, to the Sg being near or far from FMN[2]. The isoleucine 427 is quite big. But not enough to push the cystein's side chain significantly toward the cofactor. So we choose to replace this ILE427 by an PHE427, an amino acid which is much bigger and have more or less the same propreties than the ILE[2]. 3. The stop codon tga was changed for two taa.
This is the a constitutive GFP reporter driven by the cI promoter.
RBS (Elowitz 1999) -- defines RBS efficiency
Varies from -6 to +1 region from original sequence to accomodate BioBricks suffix. 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 for this part: Brian Chow
Vinay S Mahajan, Voichita D. Marinescu, Brian Chow, Alexander D Wissner-Gross and Peter Carr IAP, 2003.
Derived from the TE terminator of T7 bacteriophage between Genes 1.3 and 1.4 <genbank>V01146</genbank>.
Transcription terminator for the E.coli RNA polymerase.
Suggested by Sri Kosuri and Drew Endy as a high efficiency terminator. The 5' end cutoff was placed immediately after the TAA stop codon and the 3' end cutoff was placed just prior to the RBS of Gene 1.4 (before AAGGAG). Use anywhere transcription should be stopped when the gene of interest is upstream of this terminator.
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
Transcriptional terminator consisting of a 64 bp stem-loop.
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
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.
green fluorescent protein derived from jellyfish Aequeora victoria wild-type GFP (SwissProt: P42212
GFP (mut3b) [note that this part does not have a barcode]
Conversion of the iGEM parts registry to SBOL2.1