Part:BBa_K5034206

Poly P -> NADP

Basic Description

This basic part encodes the NADK gene which is initially from Mycobacterium tuberculosis H37Rv and we performed codon optimization on, is expressed in the PYYDT plasmid. This basic part is designed to facilitate the conversion of inorganic polyphosphate (PolyP) to nicotinamide adenine dinucleotide phosphate (NADP). The NADK enzyme is crucial for the phosphorylation of NAD to NADP, which is essential for various metabolic processes. NAD kinase is regarded as a key enzyme in NADP synthesis and, hence, in numerous cellular processes such as anabolic/biosynthetic pathways and protection against oxidative stress. In a sentence, it can convert Poly p to NADP. For the first time, we expressed this element in a strain of S. oneidensis and conducted codon optimization based on S. oneidensis.

Figure 1: Basic function of NADK

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Chassis and Genetic Context

Chassis：Shewanella oneidensis MR-1.

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

Construct features

• Promoter: Constitutive promoter for continuous expression. We use tac promoter in our experiment.

• RBS: Strong ribosome binding site for efficient translation. We use BBa-B0034 which shows the strongest translation in our experiment.

• NADK Coding Sequence: Encodes the NAD kinase enzyme.

• Terminator: Efficient transcription terminator to ensure proper mRNA processing. We use T7Te terminator in our experiment.

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

The coding sequence of the NADK enzyme has approximately 924 base pairs, consistent with our electrophoretic results.

Origin (Organism)

The NADK gene was sourced from Mycobacterium tuberculosis H37Rv strain.

Experimental Characterization and results

We first determined the change in the electroproduction capacity of S. oneidensis compared to the wild type after introducing the SNADK enzyme ("S" means that we introduced the enzyme into S. oneidensis, and "NADK" denotes the name of the enzyme we introduced) (e.g., fig3)

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

We found that S. oneidensis showed a significant increase in electricity production capacity compared to the wild type after the introduction of NADK, which is good news!

We then measured the phosphorus aggregation capacity of S. oneidensis after introduction of the enzyme(fig4), and found that it was also significantly increased compared to the wild type.

Figure 4: statistical data on the phosphorus accumulation capacity of S. oneidensis with NADK

We also determined the changes in ATP levels in S. oneidensis after introduction(fig5). We found that the ATP level of S. oneidensis increased significantly after the introduction, which is a strong evidence that the metabolic level of S. oneidensis is in a high state at this time.

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

Overall, the ability of S. oneidensis to generate electrical energy and the ability to aggregate phosphorus were significantly enhanced after the introduction of NADK, and presumably due to the enhanced metabolic strength. Given this excellent result, after combining it with the dry experiment, we intend to enter it into our next round of engineered S. oneidensis optimisation experiments!

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

Potential Applications

In bioelectrochemical Systems, utilizing NADP in microbial fuel cells for improved electron transfer and energy production. Also can be utilized in metabolic engineering, stress response studies, and biotechnological applications where enhanced NADP production is beneficial.

References

1.Mori S, Yamasaki M, Maruyama Y, Momma K, Kawai S, Hashimoto W, Mikami B, Murata K. Crystallographic studies of Mycobacterium tuberculosis polyphosphate/ATP-NAD kinase complexed with NAD. J Biosci Bioeng. 2004;98(5):391-3.