Part:BBa_K4280004
J23101-DexA70-rrnBT1-T7TE
J23101-DexA70-rrnBT1-T7TE
Profile
Name: J23101-DexA70-rrnBT1-T7TE
Base Pairs: 2148 bp
Origin: Streptococcus, synthetic
Properties: DexA70 is placed the downstream of J23101 for the expression.
Usage and Biology
BBa_K4280004 is the construct of J23101-DexA70-rrnBT1-T7TE. Dental caries or tooth decay is a common disease, which not only directly affects human oral health, but also often causes adverse symptoms in other parts of the body [1]. According to the global disease statistics in 2016, the incidence rate of dental caries in the population is second only to upper respiratory tract infection, ranking second among common disease. Dental plaque is the primary condition and initiating factor of dental caries. Research shows that the formation of dental plaque is the result of the joint action of many kinds of bacteria. Oral microorganisms based on high-throughput sequencing showed that Streptococcus mutans, lactobacillus, actinomycetes, etc. in plaque were closely related to the occurrence of caries [2-3]. They metabolize and produce various acids, causing the destruction of organic and inorganic substances in teeth to form visible cavities. Effective removal or inhibition of dental plaque formation has become an important means to prevent dental caries [4]. Brushing teeth and flossing are the most basic and practical methods to remove dental plaque, but it is difficult for many people to master and adhere to them. On the other hand, chemical agents such as chlorhexidine or triclosan, which have been used clinically, have significant cytotoxicity in vitro, as well as side effects such as tooth staining. Although fluoride can prevent dental caries by enhancing the acid resistance of teeth, it is difficult to ensure the stability of fluoride concentration. In this sense, the demand for new antibacterial substances from other sources is increasing. Phage lyase is a kind of glycoside hydrolase encoded by phage, which has the function of digesting the cell wall of bacterial host cell. When phage lyase acts on gram-negative bacteria, it shows high bactericidal activity, species specificity and safety in vitro and in vivo, so it has broad application prospects [5]. Biofilm is a highly organized and structured bacterial cell community hidden in the extracellular matrix. Most biofilm substrates are polysaccharides, and dental biofilms are no exception. (1-3) and (1-6) -α-D-glucan polysaccharides are the main components of Streptococcus mutans biofilm matrix. The biofilm produced by Streptococcus mutans is the main obstacle to the effect of various antibacterial agents. The best treatment must be able to eradicate biofilms. Glucanase can inhibit biofilm by hydrolyzing α-1,6-glycosidic bond. Studies have shown that dextranase DexA can inhibit the formation of biofilm and destroy the pre formed biofilm in vitro [6-7].
Construct design
1. Construction of the J23101-DexA70-rrnBT1-T7TE
The schame of the construction of J23101-DexA70-rrnBT1-T7TE was shown as figure
The profiles of every basic part are as follows:
BBa_K4280000
Name: J23101
Base Pairs: 35 bp
Origin: E.coli, genome
Properties: a strong constitutive promotor.
Usage and Biology
BBa_K4280000 is a commonly used strong constitutive promotor in bacteria.
BBa_K4280001
Name: dexA70
Base Pairs: 1899 bp
Origin: Streptococcus, genome
Properties: a Sec-dep a phage lyase with glycoside hydrolase activity acting against bacteria.
Usage and Biology
BBa_K4280001 is the coding sequence of DexA70, and it could inhibit the formation of biofilm and destroy the pre formed biofilm in vitro.
BBa_K4280002
Name: ompA signal peptide
Base Pairs: 63 bp
Origin:E.coli, genome
Properties: encoding the signal peptide of the OmpA protein.
Usage and Biology
BBa_K4280002 is the signal peptide of the OmpA protein, and it has been used for the secretion of proteins downstream.
BBa_K4280003
Name: rrnBT1-T7TE
Base Pairs: 87 bp
Origin:E.coli, genome
Properties: a transcriptional terminator.
Usage and Biology
BBa_K4280003 is the commonly used transcriptional terminators in the expression of heteroglous proteins in the engineering E. coli strains.
Experimental approach
1. PCR amplification.
For the construction, we firstly amplified DexA and pUC57 fragments by PCR assay. As indicated in Figure 3, DexA and pUC57 strands were correctly replicated.
Identification of DexA (1899 bp) and pUC57 (2126 bp) DNA strands by agarose gel electrophoresis.
2. Enzymatic digestion verification.
Secondly, we used double enzyme digestion to construct puc57-kan-mini-J23101-OmpA-smDexA-TT plasmid. PCR was used to verify the monoclonal colony of the strain. As indicated in Figure 2, 1 and 2 were positive clones.
Identification of puc57-kan-mini-J23101-OmpA-smDexA-TT by agarose gel electrophoresis.
3. Sequning of constructed puc57-kan-mini-J23101-OmpA-smDexA-Ttplasmid.
Thirdly, gene sequencing is used to double verification. As indicated in Figure 5, puc57-kan-mini-J23101-OmpA-smDexA-TT sequence was correct.
4. SDS-PAGE analysis of the target protein.
Fourthly, J23101-OmpA-smDexA-TT was purified according to the protocol. Then we used SDS-PAGE to test the purity of puc57-kan-mini-J23101-OmpA-smDexA-TT. As shown in Figure 6, the puc57-kan-mini-J23101-OmpA-smDexA-TT was purified successfully.
Glue diagram of DexA and ClyR proteins. MS is medium supernatant, P is precipitation, and S is supernatant. The molecular weight of DexA protein is 74.33 kDa. The molecular weight of ClyR protein was 30.49 kDa.
5. Activity assassy.
Finally, we test the function of the strain. As indicated in Figure 7, The plasmid we constructed had a good bactericidal effect.
Improvement of an existing part
Compared to the old part projects BBa_K4030009，which is a biological part submitted by iGEM21_Shanghai_United_HS in 2021, the ClyR is under araBAD promoter, which is induced by arabinose. And ClyR is linked with ompA and this sequence is inserted into plasmid. The constructed plasmid exhibited weak activity. In this part, we selected the dextranase DexA. DexA can inhibit the formation of biofilm and destroy the pre formed biofilm dextranase DexA in vitro. We designed a genetically engineered bacterium that produces a glucanase DexA and a phage lyase ClyR. The former can effectively prevent the formation of biofilm and dissolve the formed biofilm, while the latter can specifically kill Streptococcus mutans. The genetically engineered bacteria prepared in this project have great potential in the prevention and treatment of dental caries.
Reference
1.Yang, H. et al. A chimeolysin with extended-spectrum streptococcal host range found by an induced lysis-based rapid screening method. Sci. Rep. 5, 17257; doi: 10.1038/srep17257 (2015).
2.McGowan S, Buckle AM, Mitchell MS, Hoopes JT, Gallagher DT, Heselpoth RD, Shen Y, Reboul CF, Law RH, Fischetti VA, Whisstock JC, Nelson DC. X-ray crystal structure of the streptococcal specific phage lysin PlyC. Proc Natl Acad Sci U S A. 2012 Jul 31;109(31):12752-7. doi: 10.1073/pnas.1208424109.
3. Seo EJ, Weibel S, Wehkamp J, Oelschlaeger TA. Construction of recombinant E. coli Nissle 1917 (EcN) strains for the expression and secretion of defensins. Int J Med Microbiol. 2012 Nov;302(6):276-87. doi: 10.1016/j.ijmm.2012.05.002.
4. Liu N, Li X, Wang M, Zhang F, Wang C, Zhang K, Wang H, Xu S, Hu W, Gu L. DexA70, the Truncated Form of a Self-Produced Dextranase, Effectively Disrupts Streptococcus mutans Biofilm. Front Microbiol. 2021 Sep 28;12:737458. doi: 10.3389/fmicb.2021.737458.
5. Ogawa A, Furukawa S, Fujita S, Mitobe J, Kawarai T, Narisawa N, Sekizuka T, Kuroda M, Ochiai K, Ogihara H, Kosono S, Yoneda S, Watanabe H, Morinaga Y, Uematsu H, Senpuku H. Inhibition of Streptococcus mutans biofilm formation by Streptococcus salivarius FruA. Appl Environ Microbiol. 2011 Mar;77(5):1572-80. doi: 10.1128/AEM.02066-10.
6. Liu N, Li X, Wang M, Zhang F, Wang C, Zhang K, Wang H, Xu S, Hu W, Gu L. DexA70, the Truncated Form of a Self-Produced Dextranase, Effectively Disrupts Streptococcus mutans Biofilm. Front Microbiol. 2021 Sep 28;12:737458. doi: 10.3389/fmicb.2021.737458.
7. Zayed SM, Aboulwafa MM, Hashem AM, Saleh SE. Biofilm formation by Streptococcus mutans and its inhibition by green tea extracts. AMB Express. 2021 May 25;11(1):73. doi: 10.1186/s13568-021-01232-6. PMID: 34032940; PMCID: PMC8149520.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 7
Illegal NheI site found at 30 - 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000INCOMPATIBLE WITH RFC[1000]Illegal SapI.rc site found at 1229
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