Architecture

Philosophy and Design of SEGA

SEGA: The Standardized Genome Architecture

In the Standardized Genome Architecture (SEGA) , genomic integration of DNA fragments is enabled by λ-Red recombineering and so-called landing pads that are a common concept in synthetic biology and typically contain features that i) enable insertion of additional genetic elements and ii) provide well-characterized functional parts such as promoters and genes, and iii) provides insulation against genome context-dependent effects. The SEGA landing pads allow for reusable homology regions and time-efficient construction of parallel genetic designs with a minimal number of reagents and handling steps. SEGA strains can be stored as ready-to-use competent cryostocks with the recombineering machinery activated. This heavily simplifies the genome engineering process for the end-user. SEGA bricks, typically synthetic DNA or PCR fragments, are integrated on the genome simply by combining the two reagents (i.e. competent cells and DNA), followed by incubation steps, and successful recombinants are identified by visual inspection on agar plates. The design of the SEGA standard was heavily influenced by the Standard European Vector Architecture (SEVA) and the following module definitions were adopted.

The Landing Pad

Control Elements

Control Element 1

represents experimentally validated promoters:

  • J23100
  • Ptrc
  • PrhaBAD
  • PT7

Control Element 2

represents experimentally validated Translation Initiation Regions (TIRs):

  • low
  • medium
  • high

SEGA landing pads typically hosts two major genetic “control elements” that influence gene expression on the transcriptional (C1), and translational (C2) level

Gadgets

According to the SEVA plasmid standard a gadget is "a dispensable DNA sequence that confers new utilities or properties to the basic frame..." 

Upstream Gadget

allows for the exchange of control elements

Middle Gadget

provides additional features such as gene expression buffers, signal peptides or peptide tags

Downstream Gadget

allows for the exchange of the cargo

Cargos

According to the SEVA plasmid standard a cargo is "the DNA portion that bears the main functionality..."

Cargo

all SEGA strains come with gfp as the preliminary cargo that allows for green-white screening when it is exchanged for a new cargo

Others

Terminators

flanking terminators were added to minimize polar effects on host genes and vice versa