heme oxygenase (ho1) from Synechocystis
Sequence and Features
- 10COMPATIBLE WITH RFC
- 12COMPATIBLE WITH RFC
- 21COMPATIBLE WITH RFC
- 23COMPATIBLE WITH RFC
- 25COMPATIBLE WITH RFC
- 1000COMPATIBLE WITH RFC
One of two requisite genes required for the biosynthesis of phycocyanobilin from heme.
Usage and Biology
ho1 oxidizes the heme group using a ferredoxin cofactor, generating biliverdin IXalpha and representing the first of two steps in phycocyanobilin (PCB) biosynthesis. PCB associates with Cph8, creating a light responsive protein complex. Functions in tandem with BBa_I15009 for PCB biosynthesis. PCB then associates with Part:BBa_I15010, a light responsive Cph8/EnvZ fusion protein.
The infomation below is updated by TJU_China of iGEM 2017.
We exchange the position of sequence window and the text.
The original part has a barcode after coding sequence. So we submit a new part Part:BBa_K2328062 (without the barcode) for our composite parts. We will upload the data and infomation in all pages related to HO-1.
In addition, in order to make this part express better in hosts of our project (several intestinal bacteria), we optimize the codons of the part and submit another two new parts: Part:BBa_K2328003 for E.coli, EHEC, Citrobacter rodentium, Lactococcus Iactis, Bacaeroides fragilis, Enterococcus faecalis and Clostridium difficile and Part:BBa_K2328004 for Bifidobacterium longum. We do codon optimization for two obligate anaerobes just want to comfirm that this gene cannot work at all in obligate anarobes, which means HO-1 gene doesn't make any sense in these two bacteria, at least for now.
A novel far-red fluorescent protein evolved from APCα from Trichodesmium erythraeum, called smURFP, can covalently attaches a biliverdin (BV) chromophore without a lyase, unlike its precursor APC which should use an auxiliary protein known as a lyase to incorporate phycocyanobilin. In addition, phycocyanobilin (PCB) is synthesized from BV, and PCB do not exists in mammals but BV does. So BV is better as a chromophore in some way, along with smURFP.
In our projext, we use HO-1 gene for two task: one is to produce BV in E.coli BL21, the other is to be a element in co-expression system (with fluorescent protein smURFP).
The sequence was taken by the St Andrews iGEM 2020 team and subject to the IDT codon optimisation tool. As a result of optimisation, two illegal restriction sites were introduced to the part and then removed to allow the part to be used at RFC and RFC standard with codon optimisation (BBa_K3634007)
- I. BV production
We use this part to prduce Biliverdin (BV) in E.coli BL-21. As shown in the picture, we can see the obvious change if medium in color.
Figure 1. The result after induction, the upper one is the control group, and the inferior one is the experimental group.
- II. Co-expression with smURFP
Plasmid pET28b with smURFP and HO-1 gene were transformed into E. coli BL-21. We used this induced bacteria to confirm the fluorescence and data showed a relatively high value, as shown in table 1.
Table 1. Result of Microplate Reader in the black 96-well plate. Tube 1 and 2 are experimental group, and tube 3 is the control group.
Then laser confocal microscopy was use to observe these bacteria, activate light of 640nm was used, as shown in Figure 2.
Figure 2. The result after induction, the upper one is the control group, and the inferior one is the experimental group.
After tests in vitro, we used this engineered bacteria for experiments in vivo. Utilizing Animal imaging system, we consistently observed the fluorescence emitted from the bacteria in mices' gut. The result successfully showed that our system was executable and excellent. And smURFP has very competible persistence and penetrability.
Figure 8. The fluorescent inensity after doing intragastric administration for 5.5h.The left is the control one, the right is the experimental one.
For other experiments for some intestinal bacteria, we use our codon-optimized gene to express HO-1 in facultative anarobes.
 Rodriguez EA, Tran GN, Gross LA, Crisp JL, Shu X, Lin JY, Tsien RY. A far-red fluorescent protein evolved from a cyanobacterial phycobiliprotein. Nat Methods. 2016 Sep;13(9):763-9.
 HO-1 I (without a barcode) Part:BBa_K2328062
 HO-1 II codon-optimized for intestinal bacteria Part:BBa_K2328003
 HO-1 III codon-optimized for Bifidobacterium longum Part:BBa_K2328004