Basic Part
Name Description Type Designer Length(bp)
BBa_K4060000 MazE antitoxin coding Yi Rong Chen 282
BBa_K4060001 MazF toxin coding Yi Rong Chen 371
BBa_K4060020 aprN (Nattokinase) coding Yan-Zhen, Chen 1146
BBa_K4060021 pelB leader sequence with aprN (without native signal peptide sequence) coding Yan-Zhen, Chen 1134
BBa_K4060505 BphP1 coding Cheng-Ju, Lu 2196
BBa_K4060506 QPAS1 coding Cheng-Ju, Lu 453
BBa_K4060507 BphP1_mCherry fusion protein coding Cheng-Ju, Lu 2943
BBa_K4060508 QPAS1_mCherry fusion protein coding Cheng-Ju, Lu 1203
BBa_K4060509 mCherry_QPAS1 fusion protein coding Cheng-Ju, Lu 1203
BBa_K4060510 LexA coding Cheng-Ju, Lu 612
BBa_K4060511 LexA_QPAS1 fusion protein coding Cheng-Ju, Lu 1077
BBa_K4060512 mCherry gene with flexible linker coding Cheng-Ju, Lu 753
Composite Part
Name Descrpition Type Designer Length(bp)
BBa_K4060100 [Pre A1] pBad promoter with RBS composite Yi-Rong Chen 150
BBa_K4060101 [Pre A2] double terminator + pTetR composite Yi-Rong Chen 191
BBa_K4060102 [Pre A3] a RFP gene with double terminator composite Yi-Rong Chen 843
BBa_K4060103 [Pre A4] a pBad with J23106 composite Yi-Rong Chen 173
BBa_K4060104 [Pre B1] Pre A1 with TetR composite Yi-Rong Chen 841
BBa_K4060105 [Pre B2] Pre A2 with thermometer RBS composite Yi-Rong Chen 251
BBa_K4060106 [Pre B3] Pre A1 with Pre A3 composite Yi-Rong Chen 999
BBa_K4060107 [Pre B4] Pre A4 with RBS composite Yi-Rong Chen 193
BBa_K4060108 [Pre C1] Pre B4 with Pre A3 composite Yi-Rong Chen 1042
BBa_K4060109 [Pre C2] J23106 with Pre B3 composite Yu-Chuan Lee 1042
BBa_K4060110 [Const1] Pre B1+Pre B2+MazE+His-tag+B0015 composite Yu-Chuan Lee 1547
BBa_K4060111 [Const2] Pre B1+Pre B2+Pre A3 composite Yu-Chuan Lee 1969
BBa_K4060112 [pJ102] pBad with J23102 composite Yu-Chuan Lee 173
BBa_K4060113 [pJ118] pBad with J23118 composite Yu-Chuan Lee 173
BBa_K4060114 [pJ110] pBad with J23110 composite Yu-Chuan Lee 173
BBa_K4060115 [pJ116] pBad with J23116 composite Yu-Chuan Lee 173
BBa_K4060116 [pJ113] pBad with J23113 composite Yu-Chuan Lee 173
BBa_K4060117 pJ102+thermometer RBS+MazE+Double terminator+Pre C1+Pre A4+Double terminator composite Yu-Chuan Lee 1297
BBa_K4060500 ho1 gene with B0015 double terminator composite Cheng-Ju, Lu 888
BBa_K4060501 BBa_K4060500 with BBa_K763004 composite Cheng-Ju, Lu 1631
BBa_K4060502 Promoter BBa_J23110 with RBS BBa_B0030 composite Cheng-Ju, Lu 58
BBa_K4060503 Double terminator BBa_B0015 + Promoter BBa_J23110 + RBS BBa_B0030 composite Cheng-Ju, Lu 195
BBa_K4060504 BBa_K4060503 + BBa_K4060501 composite Cheng-Ju, Lu 1832
BBa_K4060513 BBa_K4060503+ BBa_K4060505 composite Cheng-Ju, Lu 2399
BBa_K4060514 BBa_K4060503 + BBa_K4060506 composite Cheng-Ju, Lu 656
BBa_K4060515 BBa_K4060513 + BBa_K4060514 composite Cheng-Ju, Lu 3063
BBa_K4060516 BBa_K4060513 + BBa_K4060514 + BBa_K4060504 composite Cheng-Ju, Lu 4903
BBa_K4060517 BBa_K4060503 + BBa_K4060511 composite Cheng-Ju, Lu 1406
BBa_K4060518 BBa_K4060503 + BBa_K4060509 composite Cheng-Ju, Lu 1404
BBa_K4060519 BBa_K4060503 + BBa_K4060508 composite Cheng-Ju, Lu 1406
BBa_K4060520 BBa_K4060513 + BBa_K4060517 +
composite Cheng-Ju, Lu 5653
BBa_K4060521 BBa_K4060513 + BBa_K4060519 composite Cheng-Ju, Lu 3813
BBa_K4060522 BBa_K4060513 + BBa_K4060518 composite Cheng-Ju, Lu 3811
BBa_K4060523 BBa_K4060513 + BBa_K4060517 composite Cheng-Ju, Lu 3813
Improvement of Existing Parts

One of our goals is to create a better L-arabinose induced constitutive promoter. Here, we used a constitutive promoter (BioBrick_BBa_J23106) to co-regulate with pBad promoter (BBa_K206000). The pBad promoter is a positively regulated promoter, which will be inhibited by araC without the presence of L-arabinose. The L-arabinose can bind with araC and turn araC from a promoter inhibitor to a promoter inducer.

In our kill switch design, we hope to generate a stronger pBad promoter with greater expression rate and wider inducing range. With the regulation of both constitutive promoter and L-arabinose induced pBad promoter, we hope it can help the pBad to increase its expression ability.
Fig 1. A schematic of our biobrick construction.
In other words, we are trying to improve BioBrick_BBa_K206000. We want to ligate pBad promoter with a constitutive promoter to form a tandem promoter. We hypothesized that by adding a constitutive promoter beside pBad, the expression of the tandem promoter will be better than the normal pBad promoter (BioBrick_BBa_K206000). We compared the intensity of RFP gene constructed behind the pBad promoter and pBad-J23106 tandem promoter to see if the tandem promoter has better expression rate.

Experiment Results

RFP Intensity Experiment
We made a series of liquid cultures with different concentrations of L-arabinose. Then, we cultured E. coli  DH5-alpha with pBad and pBad-J23106 separately. After making the bacteria shake at 24°C for 24 hrs, we tested the RFP intensity and OD600 of these liquid cultures.
Fig 2. The comparison between pBad and pBad-J23106 after 24hrs induction.
According to the figure, we can see that pBad-J23106 significantly outshines the original BioBrick_BBa_K206000. When the L-arabinose is lower than 0.025 M, both the pBad and pBad-J23106 promoters were induced. The RFP intensity of the improved part pBad-J23106 reached about 17000 at the L-arabinose concentration of 0.025, which is eight times higher than the original part pBad. The expression rate of pBad-J23106 still exceeds the origin part pBad at the concentration of L-arabinose higher than 0.025. We implemented this design in our kil-switch. Please visit our project Results page for more information.


[1] Öztürk, S., Ergün, B. G., & Çalık, P. (2017). Double promoter expression systems for recombinant protein production by industrial microorganisms. Applied microbiology and biotechnology, 101(20), 7459–7475.

Authored and maintained by Team NYCU-Taipei 2021.