BBa_K142005
1
BBa_K142005
lacI IS mutant (IPTG unresponsive) R197A T276F
2008-10-24T11:00:00Z
2015-05-08T01:10:22Z
The lacI IS mutants presented derive from the BioBrick holding lacI by itself (C0012). Site-directed mutagenesis was performed by PCR, subsequent DpnI digest and transformation. The following primers were used:
R197F forward
CGGCGCGTCTGTTTCTGGCTGGCTG
R197A forward
CGGCGCGTCTGGCGCTGGCTGGCTG
R197F reverse
CAGCCAGCCAGAAACAGACGCGCCG
R197A reverse
CAGCCAGCCAGCGCCAGACGCGCCG
T276F forward
GGATACGACGATTTTGAAGACAGCTC
T276A forward
GGATACGACGATGCGGAAGACAGCTC
T276F reverse
GAGCTGTCTTCAAAATCGTCGTATCC
T276A reverse
GAGCTGTCTTCCGCATCGTCGTATCC
All lacI IS holding BioBricks were verified by sequencing.
lacI IS mutant (IPTG unresponsive)
Short description: The lacI IS mutant is almost identical to the lacI transcriptional regulator except for the difference that it is not able to bind IPTG or allolactose due to a mutation; it therefore can not be activated by induction with these substances. Since it recognizes the same motif in the lac promotor region, it strongly represses transcription of all genes regulated by promotors with lacI binding site even if IPTG or allolactose are present. It can be used to terminate the expression of proteins under lac control if IPTG can not be removed from the cell rapidly.
Detailed description: Expression of the lac operon in E. coli is tightly controlled by lacI, a protein, which binds to a repressor binding site within the promotor and disables transcription by obscuring the promotor region. When bound to DNA, lacI is in the tetrameric form, which consists of two dimers interacting at the end distal from the DNA binding site. Upon binding of allolactose or IPTG, the tetramer breaks down into two dimers and the affinity for the repressor binding site is greatly reduced; the lacI IPTG complex will diffuse away from the repressor binding site, leaving the promotor accessible. As a result of decades of genetic and structural studies, the function of lacI is now understood on the molecular level (1, 2). Mutational experiments have identified residues, which abolish IPTG response upon mutation (3). Furthermore, the x-ray crystal structure of lacI with bound IPTG has allowed the identification of residues that interact with IPTG and which are promising targets for mutagenesis (1). We decided to mutate residues R197 and T276, which are located in the IPTG binding groove, contact IPTG and have been shown to produce the lacI IS mutation in previous genetic experiments. Since a quantitative study of the strength of inhibition by different lacI IS mutants has to our knowledge not been published so far, we decided to generate a set of eight mutated lacIs, in which we replaced either R197 with alanine or phenylalanine or T276 with alanine or phenylalanine or both in all possible combinations.
lacIIS-1: R197A
lacIIS-2: R197F
lacIIS-3: T276A
lacIIS-4: T276F
lacIIS-5: R197A T276A
lacIIS-6: R197A T276F
lacIIS-7: R197F T276A
lacIIS-8: R197F T276F
References:
(1) Lewis, M., Chang, G., Horton, N. C., Kercher, M. A., Pace, H. C., Schumacher, M. A., Brennan, R. G., and Lu, P. (1996) Crystal structure of the lactose operon repressor and its complexes with DNA and inducer. Science 271, 1247-54.
(2) Friedman, A. M., Fischmann, T. O., and Steitz, T. A. (1995) Crystal structure of lac repressor core tetramer and its implications for DNA looping. Science 268, 1721-7.
(3) Suckow, J., Markiewicz, P., Kleina, L. G., Miller, J., Kisters-Woike, B., and Muller-Hill, B. (1996) Genetic studies of the Lac repressor. XV: 4000 single amino acid substitutions and analysis of the resulting phenotypes on the basis of the protein structure. J Mol Biol 261, 509-23.
false
false
_194_
0
3254
9
It's complicated
false
During site-directed mutagenesis, the codons to be mutated were replaced with the most highly utilized codons in E. coli to prevent complications from the use of rare codons. The lacI IS sequences were analyzed for BioBrick restriction sites within the coding sequence to ensure their compatibility.
false
Julius Rabl
annotation1987410
1
lacI IS
range1987410
1
1
1128
BBa_K142013
1
BBa_K142013
lacI IS mutant R197A T276F with RBS and terminator
2008-10-28T12:00:00Z
2015-05-08T01:10:22Z
The lacI IS mutant presented derive from the BioBrick I763026, which as it turned out during sequencing by the Caltech team, did not have a promotor. Site-directed mutagenesis was performed by PCR, subsequent DpnI digest and transformation. The following primers were used for mutagenesis:
R197F forward
CGGCGCGTCTGTTTCTGGCTGGCTG
R197A forward
CGGCGCGTCTGGCGCTGGCTGGCTG
R197F reverse
CAGCCAGCCAGAAACAGACGCGCCG
R197A reverse
CAGCCAGCCAGCGCCAGACGCGCCG
T276F forward
GGATACGACGATTTTGAAGACAGCTC
T276A forward
GGATACGACGATGCGGAAGACAGCTC
T276F reverse
GAGCTGTCTTCAAAATCGTCGTATCC
T276A reverse
GAGCTGTCTTCCGCATCGTCGTATCC
==lacI IS mutant (IPTG unresponsive) with ribosome binding site and terminator==
===Short description:===
The lacI IS mutant is almost identical to the lacI transcriptional regulator except for the difference that it is not able to bind IPTG or allolactose due to a mutation; it therefore can not be activated by induction with these substances. Since it recognizes the same motif in the lac promotor region, it strongly represses transcription of all genes regulated by promotors with lacI binding site even if IPTG or allolactose are present. It can be used to terminate the expression of proteins under lac control if IPTG can not be removed from the cell rapidly.
===Detailed description:===
Expression of the lac operon in E. coli is tightly controlled by lacI, a protein, which binds to a repressor binding site within the promotor and disables transcription by obscuring the promotor region. When bound to DNA, lacI is in the tetrameric form, which consists of two dimers interacting at the end distal from the DNA binding site. Upon binding of allolactose or IPTG, the tetramer breaks down into two dimers and the affinity for the repressor binding site is greatly reduced; the lacI IPTG complex will diffuse away from the repressor binding site, leaving the promotor accessible. As a result of decades of genetic and structural studies, the function of lacI is now understood on the molecular level (1, 2). Mutational experiments have identified residues, which abolish IPTG response upon mutation (3). Furthermore, the x-ray crystal structure of lacI with bound IPTG has allowed the identification of residues that interact with IPTG and which are promising targets for mutagenesis (1).
[[image:jr_pulsegen_1.jpg|frame|none|
Figure 3: A Lac repressor tetramer, residues R197 and T276 are shown in red. B IPTG bound to the inducer binding site of the lac repressor, residues R197 and T276 are shown in green. Molecular graphics was generated from coordinate set [http://www.rcsb.org/pdb/explore.do?structureId=1LBH 1lbh] (1) using [http://www.cgl.ucsf.edu/chimera/ UCSF Chimera].]]
We decided to mutate residues R197 and T276, which are located in the IPTG binding groove, contact IPTG and have been shown to produce the lacI IS mutation in previous genetic experiments. Since a quantitative study of the strength of inhibition by different lacI IS mutants has to our knowledge not been published so far, we decided to generate a set of eight mutated lacIs, in which we replaced either R197 with alanine or phenylalanine or T276 with alanine or phenylalanine or both in all possible combinations.
lacIIS-1: R197A
lacIIS-2: R197F
lacIIS-3: T276A
lacIIS-4: T276F
lacIIS-5: R197A T276A
lacIIS-6: R197A T276F
lacIIS-7: R197F T276A
lacIIS-8: R197F T276F
This BioBrick is based on BioBrick I763026 and contains a ribosome binding site, the lacI IS gene and a double terminator. As sequencing by Caltech has shown that BioBrick I763026 did not have a promotor this BioBrick is promotorless, too. Expression of the mutant LacI IS (and silencing of lac-controlled gene expression) can therefore be controlled by any promotor of choice if this BioBrick is cloned behind it.
===References:===
(1) Lewis, M., Chang, G., Horton, N. C., Kercher, M. A., Pace, H. C., Schumacher, M. A., Brennan, R. G., and Lu, P. (1996) Crystal structure of the lactose operon repressor and its complexes with DNA and inducer. Science 271, 1247-54.
(2) Friedman, A. M., Fischmann, T. O., and Steitz, T. A. (1995) Crystal structure of lac repressor core tetramer and its implications for DNA looping. Science 268, 1721-7.
(3) Suckow, J., Markiewicz, P., Kleina, L. G., Miller, J., Kisters-Woike, B., and Muller-Hill, B. (1996) Genetic studies of the Lac repressor. XV: 4000 single amino acid substitutions and analysis of the resulting phenotypes on the basis of the protein structure. J Mol Biol 261, 509-23.
false
false
_194_
0
3254
9
It's complicated
false
During site-directed mutagenesis, the codons to be mutated were replaced with the most highly utilized codons in E. coli to prevent complications from the use of rare codons. The lacI IS sequences were analyzed for BioBrick restriction sites within the coding sequence to ensure their compatibility.
false
Julius Rabl
component1993764
1
BBa_B0010
component1993766
1
BBa_B0012
component1993761
1
BBa_B0034
component1993763
1
BBa_K142005
annotation1993763
1
BBa_K142005
range1993763
1
19
1146
annotation1993764
1
BBa_B0010
range1993764
1
1155
1234
annotation1993761
1
BBa_B0034
range1993761
1
1
12
annotation1993766
1
BBa_B0012
range1993766
1
1243
1283
BBa_B0012
1
BBa_B0012
TE from coliphageT7
2003-01-31T12:00:00Z
2015-08-31T04:07:20Z
Derived from the TE terminator of T7 bacteriophage between Genes 1.3 and 1.4 <genbank>V01146</genbank>.
Released HQ 2013
Transcription terminator for the <i>E.coli</i> RNA polymerase.
false
false
_1_
0
24
7
In stock
false
<P> <P>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).<P> Use anywhere transcription should be stopped when the gene of interest is upstream of this terminator.
false
Reshma Shetty
annotation1686
1
T7 TE
range1686
1
8
27
annotation1687
1
stop
range1687
1
34
34
annotation1690
1
polya
range1690
1
28
41
annotation7020
1
BBa_B0012
range7020
1
1
41
BBa_B0010
1
BBa_B0010
T1 from E. coli rrnB
2003-11-19T12:00:00Z
2015-08-31T04:07:20Z
Transcriptional terminator consisting of a 64 bp stem-loop.
false
false
_1_
0
24
7
In stock
false
true
Randy Rettberg
annotation4184
1
stem_loop
range4184
1
12
55
annotation7018
1
BBa_B0010
range7018
1
1
80
BBa_B0034
1
BBa_B0034
RBS (Elowitz 1999) -- defines RBS efficiency
2003-01-31T12:00:00Z
2015-08-31T04:07:20Z
Released HQ 2013
RBS based on Elowitz repressilator.
false
true
_1_
0
24
7
In stock
false
Varies from -6 to +1 region from original sequence to accomodate BioBricks suffix. <p>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: <a href="mailto:(bchow@media.mit.edu)">Brian Chow</a>
true
Vinay S Mahajan, Voichita D. Marinescu, Brian Chow, Alexander D Wissner-Gross and Peter Carr IAP, 2003.
annotation23325
1
conserved
range23325
1
5
8
BBa_B0010_sequence
1
ccaggcatcaaataaaacgaaaggctcagtcgaaagactgggcctttcgttttatctgttgtttgtcggtgaacgctctc
BBa_B0034_sequence
1
aaagaggagaaa
BBa_K142013_sequence
1
aaagaggagaaatactagatggtgaatgtgaaaccagtaacgttatacgatgtcgcagagtatgccggtgtctcttatcagaccgtttcccgcgtggtgaaccaggccagccacgtttctgcgaaaacgcgggaaaaagtggaagcggcgatggcggagctgaattacattcccaaccgcgtggcacaacaactggcgggcaaacagtcgttgctgattggcgttgccacctccagtctggccctgcacgcgccgtcgcaaattgtcgcggcgattaaatctcgcgccgatcaactgggtgccagcgtggtggtgtcgatggtagaacgaagcggcgtcgaagcctgtaaagcggcggtgcacaatcttctcgcgcaacgcgtcagtgggctgatcattaactatccgctggatgaccaggatgccattgctgtggaagctgcctgcactaatgttccggcgttatttcttgatgtctctgaccagacacccatcaacagtattattttctcccatgaagacggtacgcgactgggcgtggagcatctggtcgcattgggtcaccagcaaatcgcgctgttagcgggcccattaagttctgtctcggcgcgtctggcgctggctggctggcataaatatctcactcgcaatcaaattcagccgatagcggaacgggaaggcgactggagtgccatgtccggttttcaacaaaccatgcaaatgctgaatgagggcatcgttcccactgcgatgctggttgccaacgatcagatggcgctgggcgcaatgcgcgccattaccgagtccgggctgcgcgttggtgcggatatctcggtagtgggatacgacgattttgaagacagctcatgttatatcccgccgttaaccaccatcaaacaggattttcgcctgctggggcaaaccagcgtggaccgcttgctgcaactctctcagggccaggcggtgaagggcaatcagctgttgcccgtctcactggtgaaaagaaaaaccaccctggcgcccaatacgcaaaccgcctctccccgcgcgttggccgattcattaatgcagctggcacgacaggtttcccgactggaaagcgggcaggctgcaaacgacgaaaactacgctttagtagcttaataatactagagccaggcatcaaataaaacgaaaggctcagtcgaaagactgggcctttcgttttatctgttgtttgtcggtgaacgctctctactagagtcacactggctcaccttcgggtgggcctttctgcgtttata
BBa_K142005_sequence
1
atggtgaatgtgaaaccagtaacgttatacgatgtcgcagagtatgccggtgtctcttatcagaccgtttcccgcgtggtgaaccaggccagccacgtttctgcgaaaacgcgggaaaaagtggaagcggcgatggcggagctgaattacattcccaaccgcgtggcacaacaactggcgggcaaacagtcgttgctgattggcgttgccacctccagtctggccctgcacgcgccgtcgcaaattgtcgcggcgattaaatctcgcgccgatcaactgggtgccagcgtggtggtgtcgatggtagaacgaagcggcgtcgaagcctgtaaagcggcggtgcacaatcttctcgcgcaacgcgtcagtgggctgatcattaactatccgctggatgaccaggatgccattgctgtggaagctgcctgcactaatgttccggcgttatttcttgatgtctctgaccagacacccatcaacagtattattttctcccatgaagacggtacgcgactgggcgtggagcatctggtcgcattgggtcaccagcaaatcgcgctgttagcgggcccattaagttctgtctcggcgcgtctggcgctggctggctggcataaatatctcactcgcaatcaaattcagccgatagcggaacgggaaggcgactggagtgccatgtccggttttcaacaaaccatgcaaatgctgaatgagggcatcgttcccactgcgatgctggttgccaacgatcagatggcgctgggcgcaatgcgcgccattaccgagtccgggctgcgcgttggtgcggatatctcggtagtgggatacgacgattttgaagacagctcatgttatatcccgccgttaaccaccatcaaacaggattttcgcctgctggggcaaaccagcgtggaccgcttgctgcaactctctcagggccaggcggtgaagggcaatcagctgttgcccgtctcactggtgaaaagaaaaaccaccctggcgcccaatacgcaaaccgcctctccccgcgcgttggccgattcattaatgcagctggcacgacaggtttcccgactggaaagcgggcaggctgcaaacgacgaaaactacgctttagtagcttaataa
BBa_B0012_sequence
1
tcacactggctcaccttcgggtgggcctttctgcgtttata
igem2sbol
1
iGEM to SBOL conversion
Conversion of the iGEM parts registry to SBOL2.1
James Alastair McLaughlin
Chris J. Myers
2017-03-06T15:00:00.000Z