Gene synthesis
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Synthesis of non-standard and complex genes:

Complex genes can be a challenge for traditional cloning efforts but also for gene synthesis. Complex genes are characterized by uneven GC content or GC/AT extremes. This applies to various eukaryotic promoters with GC contents up to 95 per cent or some extremely AT-rich genes in e.g. Clostridium ljungdahlii.

Other common features in complex genes are secondary structures such as stem-loop structures, extended (direct or inverted) repeats, hairpin structures, polynucleotide stretches, etc.
Optimization algorithms and smart design can help overcome such impediments to synthesis.

Figure 1: Example of highly repetitive gene sequence with high GC content: [Click on the images for a blow-up of the pre-post comparison].
The original sequence left) had a high and cyclical GC content indicative of extended repeats (which the repeat analysis confirmed; see fig. 2). Optimization with EvoMAG lower the GC content and reduced the periodicity and length of the repeat structures into shorter segments that eventually allowed successful synthesis of the sequence.

Figure 2: Reduction of extended repeat structure: [Click on the images for a blow-up of the pre-post comparison].
The original sequence (left panle) had extended repeats which were significantly reduced after optimization with EvoMAG (right panel).