Difference between revisions of "Part:BBa K5034212"

Latest revision as of 07:48, 2 October 2024

PolyP + AMP --> ADP

It can reversibly convert PolyP and AMP to ADP. For the first time, we expressed this element in a strain of S. oneidensis and conducted codon optimization based on S. oneidensis. We tested the effects of the introduction of this element on electricity production and phosphorus metabolism.

Basic Description

This basic part encodes the PAP gene which is initially from Acinetobacter johnsonii and we performed codon optimization on, is expressed in the pBBR1MCS-terminator plasmid. This basic part is designed to facilitate the reversible conversion of inorganic polyphosphate (PolyP) and adenosine monophosphate (AMP) to adenosine diphosphate (ADP). The PAP enzyme plays a crucial role in phosphate and energy metabolism. PAP and PPK2 have strong PolyP utilization activity, and the activity of PAP is 20-fold higher than that in PPK1, even though the Km values for utilization of all three enzymes are almost the same. This implies that PAP and PPK2 work mainly for PolyP utilization in the cell. However, PAP has the same level of PolyP synthetic activity (Km and Vmax) as PPK1, and this suggests that PAP also works for PolyP synthesis at a significant level.

Figure 1: Basic function of PAP

Sequence and Features

Construct features

• Promoter: We use Lac promoter in our experiment. Since there is no LacI protein on plasmid backbone, the gene expression is constitutive. Since the plasmid backbone does not encode the regulatory gene lacI for the repressor protein, the Lac promoter can be used as a constitutive promoter. This allows the subsequent genes to be constantly expressed.
• RBS: BBa_B0034
• PAP Coding Sequence: Encodes the polyphosphate:AMP phosphotransferase enzyme.
• Terminator: Efficient transcription terminator to ensure proper mRNA processing. We use a double terminator rrnBT1-T7TE(BBa_B0015) in our experiment.

Figure 2: PCR of target genes PCR before plasmids construction (The extra small fragment in the picture is primer dimer)

The length of the PAP gene is about 1428 base pairs, which is consistent with the results on the DNA electropherogram, proving that we have obtained the PAP gene.

Origin (Organism)

The PAP gene was sourced from Acinetobacter johnsonii.

Experimental Characterization and results

We first determined the electroproduction capacity of S. oneidensis after introduction of the PAP enzyme.(Fig.3)

Figure 3: Statistical data on electricity production capacity of S. oneidensis with the introduction of different hydrolases

We found that the efficiency of bacterial inhibition of electricity production did not significantly increase after SPAP introduction, and even showed a significant decrease, so it is not a good synthetic biology component to enhance the electricity production capacity of S. oneidensis.

Afterwards, we also measured the phosphorus aggregation capacity of S. oneidensis(Fig.4) and found no significant difference from the wild type, indicating that its introduction did not promote phosphorus uptake in S. oneidensis either.

Figure 4: Statistical data on the phosphorus accumulation capacity of S. oneidensis with PAP

Tests to measure ATP levels in S. oneidensis(Fig.5) also showed that its introduction did not result in an increase in the metabolic strength of S. oneidensis either.

Figure 5: ATP level in S. oneidensis with the introduction of different hydrolases

In summary, the option of importing PAP is not a good one.

Details of all experiments can be found at the Experiments section on the Wiki.

Chassis and genetic context

Chassis：Shewanella oneidensis MR-1.

The gene can be expressed and function properly in S. oneidensis.

Potential applications

PAP, as an enzyme class for the synthesis of ADP, plays an important role in the synthesis of intracellular high-energy phosphate compounds and is a key enzyme in the regulation of the intensity of intracellular metabolism.

References

1.Itoh, H., & Shiba, T. (2004). Polyphosphate synthetic activity of polyphosphate:AMP phosphotransferase in Acinetobacter johnsonii 210A. Journal of Bacteriology, 186(15), 5178-5181.