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	<p>Oct1-DBD (BBa_K5237004) is the DNA-binding domain of the human Oct1 transcription factor (POU2F1), which binds		<p>Oct1-DBD (BBa_K5237004) is the DNA-binding domain of the human Oct1 transcription factor (POU2F1), which binds
	specifically to the octamer motif (5'-ATGCAAAT-3'). This domain is key to regulating gene expression, immune		specifically to the octamer motif (5'-ATGCAAAT-3'). This domain is key to regulating gene expression, immune
−	response, and stress adaptation. Oct1-DBD can be readily fused with other DNA binding proteins to form a functional staple for DNA-DNA proximity./p>	+	response, and stress adaptation. Oct1-DBD can be readily fused with other DNA binding proteins to form a functional staple for DNA-DNA proximity.
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Revision as of 09:04, 28 September 2024

BBa_K5237004

Half-Staple: Oct1-DBD

Oct1-DBD (BBa_K5237004) is the DNA-binding domain of the human Oct1 transcription factor (POU2F1), which binds specifically to the octamer motif (5'-ATGCAAAT-3'). This domain is key to regulating gene expression, immune response, and stress adaptation. Oct1-DBD can be readily fused with other DNA binding proteins to form a functional staple for DNA-DNA proximity.

 

Contents

• 1 Sequence overview
• 2 Usage and Biology
• 3 Assembly and part evolution
• 4 Results
• 5 References

The PICasSO Toolbox

Figure 1: Example how the part collection can be used to engineer new staples

The 3D organization of the genome plays a crucial role in regulating gene expression in eukaryotic cells, impacting cellular behavior, evolution, and disease. Beyond the linear DNA sequence, the spatial arrangement of chromatin, influenced by DNA-DNA interactions, shapes pathways of gene regulation. However, the tools to precisely manipulate this genomic architecture remain limited, rendering it challenging to explore the full potential of the 3D genome in synthetic biology. We - iGEM Team Heidelberg 2024 - have developed PICasSO, a powerful molecular toolbox based on various DNA-binding proteins to address this issue.

The PICasSO part collection offers a comprehensive, modular platform for precise manipulation and re-programming of DNA-DNA interactions using protein staples in living cells, enabling researchers to recreate natural 3D genomic interactions, such as enhancer hijacking, or to design entirely new spatial architectures for gene regulation. Beyond its versatility, PICasSO includes robust assay systems to support the engineering, optimization, and testing of new staples, ensuring functionality in vitro and in vivo. We took special care to include parts crucial for testing every step of the cycle (design, build, test, learn) when engineering new parts

At its heart, the PICasSO parts collection consists of three categories. (i) Our DNA-binding proteins include our finalized enhancer hijacking Cas staple as well as half staples that can be used by scientists to compose entirely new Cas staples in the future. We also include our simple staples that serve as controls for successful stapling and can be further engineered to create alternative, simpler and more compact staples. (ii) As functional elements, we list additional parts that enhance the functionality of our Cas and Basic staples. These consist of protease-cleavable peptide linkers and inteins that allow condition-specific, dynamic stapling in vivo. Besides staple functionality, we also include the parts to enable the efficient delivery of PICasSO's with our interkingdom conjugation system.

(iii) As the final component of our collection, we provide parts that support the use of our custom readout systems. These include components of our established FRET-based proximity assay system, enabling users to confirm accurate stapling. Additionally, we offer a complementary, application-oriented testing system for functional readout via a luciferase reporter, which allows for straightforward experimental simulation of enhancer hijacking.

The following table gives a complete overview of all parts in our PICasSO toolbox. The highlighted parts showed exceptional performance as described on our iGEM wiki and can serve as a reference. The other parts in the collection are versatile building blocks designed to provide future iGEMers with the flexibility to engineer their own custom Cas staples, enabling further optimization and innovation

Our parts collection includes:

Sequence and Features

4. Results

Oct1 was N-terminally fused to the His6-mNeonGreen. The fusion protein was expressed from a T7 based expression plasmid and subsequently purified using metal affinity chromatography with Ni-NTA beads.(Figure 1, left) DNA binding affinity was estimated with an electrophoretic mobility shift assay (EMSA). For this, three different buffer conditions were tested (Binding buffer 1: 137 mM NaCl, 2.7 mM KCl, 10 mM Na₂HPO₄, 1.8 mM KH₂HPO₄, 0.1 % (v/v) IGEPAL® CA-360, 1 mM EDTA; Binding buffer 2: 10 mM Tris, 50 mM KCl; NaP250: Na₂HPO₄, 150 mM NaCl, 250 mM Imidazol). DNA binding could only be detected for Binding buffer 1. (Figure 1, right)

Figures 1: Figure 1: SDS-PAGE analysis of His₆-mNeonGreen-Oct1-DBD.
Lane 1: raw lysate of E. coli expression culture after steril-filtration; Lane 2: Flow through of first wash (10 bed volumes of NaP10 (Na₂HPO₄, 150 mM NaCl, 10 mM Imidazol)); Lane 3: Flow through of second wash (10 bed volumes of NaP20 (Na₂HPO₄, 150 mM NaCl, 20 mM Imidazol)); Lane 4: Elution of purified protein.
1 µL of each fraction was loaded after mixing and heating with 4x Laeemli buffer, on a 4-15% TGX-Gel. The expected band size of the protein is 56 840.23 Da, highlighted in red on the gel.