Part:BBa_K4960021
Engineered Mitochondrial Uncoupler Pdp1NTD-EGFP-UCP1
Usage and Biology
Our project aims to design a system that can effectively deliver the uncoupling protein UCP1 into adipocytes via PVCs. For this, we are using BBa_K4960022 as the basic part to enables the delivery of UCP1 by serving as the payload for the PVC delivery system. UCP1 is a naturally occurring mitochondrial uncoupler protein found in brown adipose tissue of mammals. It works by transporting protons across the mitochondrial membrane, inducing a process of mitochondrial uncoupling that disconnects oxygen consumption from ATP synthesis. This uncoupling process results in the dissipation of energy in the form of heat, leading to an increase in energy expenditure and basal metabolic rate.
Special Design
In order to prevent UCP1 from forming inclusion bodies after expression in Escherichia coli and facilitate the localization of UCP1 after transfection, we introduced EGFP protein for fusion expression with UCP1. We designed a flexible peptide linker (GGSGG) to link Pdp1NTD, UCP1 and EGFP to form a fusion protein. To understand how the fusion of Pdp1NTD and EGFP affected the function of UCP1, we performed structural prediction using AlphaFold2. Interestingly, we observed an unexpected interaction between the Pdp1NTD domain and UCP1 (Figure 2c, red box), which could possibly change the local protein structure and affect the translocation and function of UCP1. With the same protocol, we predicted the structure of a few design options and found that we could simply solve this problem by swapping UCP1 and EGFP
Figure 1.AlphaFold2 prediction of Pdp1NTD-UCP1-EGFP protein structure. The unexpected interaction between SepC and UCP1 is labeled in a red box.
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This part is testing through cell experiments, that is, the Pdp1NTD-EGFP-UCP1 fusion protein was overexpressed on HEK293T cell lines using pcDNA3.1 as the carrier. Similar to the BBa_K4960032, we transfected HEK-293T cells with pNC088, a Pdp1NTD-EGFP-UCP1 expressing plasmid, and evaluated the cellular localization and function of the fusion protein at 48 h post transfection. As expected, both wide-field fluorescent imaging and live-cell confocal imaging (Fig. 2a) showed a highly specific colocalization of Pdp1NTD-EGFP-UCP1 signal with mitochondria (labeled by MTS-mcherry). Moreover, cells transfected with pNC088 showed a significantly higher glucose consumption compared to the control cells transfected with pcDNA3.1(+) vector (Fig. 2b), suggesting a significantly improved energy consumption in these cells.
Figure 2a. Localization Pdp1NTD-EGFP-UCP1 in HEK-293T cells. For wide-field microscopy, cells were transfected with pNC088 (PCMV-Pdp1NTD-EGFP-UCP1). For confocal images, cells were co-transfected with MTS-mcherry and PNC088. Photos were taken 48 h post transfection, scale bar: 100μm for wide-field microscopy and 10 μm for confocal microscopy. Data are representative images of 3 independent experiments.
[1] Kolonin MG, Saha PK, Chan L, Pasqualini R, Arap W. Reversal of obesity by targeted ablation of adipose tissue. Nat Med. 2004 Jun;10(6):625-32.
In the process of designing part, we switched the original sequence of EGFP and UCP1, and carried out the same experimental treatment as a new group of experimental groups, hoping to solve the problems encountered before.
Sequence and Feature
Functional test
References
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