Sequence constraints

Sequence Constraints and Forbidden Motifs

To ensure the physical manufacturability, genetic stability, and optimal expression of the designed constructs, the sequence generation pipeline actively screens against a predefined set of deleterious cis-acting motifs.

The presence of these motifs can interfere with downstream molecular biology applications (such as seamless cloning and vector assembly) or induce premature transcription termination during in vitro transcription (IVT), thereby negatively impacting overall RNA pseudoyield (PY).

Comprehensive Strand Screening Because double-stranded DNA behaves bi-directionally in many biological contexts, the screening process is strictly bidirectional. For every motif listed below, the pipeline automatically identifies and targets both the exact forward sequence (5' -> 3') and its corresponding reverse complement.

Targeted Motifs

Motif Sequence (5' -> 3')	Length	Motif Type / Biological Significance	Rationale for Exclusion
GCTCTTC	7 bp	SapI (BspQI) recognition site	SapI is a Type IIS restriction enzyme widely utilized in Golden Gate and other seamless cloning methodologies. Excluding internal SapI sites prevents catastrophic sequence fragmentation during standard multi-part vector assembly.
CGATCG	6 bp	PvuI recognition site	A common Type II restriction endonuclease site. Its exclusion ensures maximum flexibility and compatibility with legacy restriction-ligation cloning strategies.
CAATTG	6 bp	MfeI (MunI) recognition site	MfeI produces compatible cohesive ends with standard EcoRI restriction sites. Removing internal MfeI sites prevents off-target cleavage and unintended ligation events.
ATCTGTTA	8 bp	Class II T7 Terminator Variant	Contains the ATCTGTT base motif. Acts as a context-dependent termination signal during IVT, inducing premature transcription termination and significantly reducing RNA pseudoyield (PY).
ATCTGTTT	8 bp	Class II T7 Terminator Variant	Contains the ATCTGTT base motif. Acts as a context-dependent termination signal during IVT, negatively impacting overall full-length transcript accumulation and PY.
ATCTGTAT	8 bp	Class II T7 Terminator Variant	Contains a motif similar to the ATCTGTT Class II T7 terminator variant. Acts as a context-dependent termination signal during IVT, negatively impacting overall full-length transcript accumulation and PY.
TTCTGTTT	8 bp	Class II T7 Terminator Variant	A structural variant of the class II terminator motif. Induces premature transcription termination in a context-specific manner, drastically reducing IVT efficiency and PY.

Note on Sequence Design: The pipeline ensures that the removal of these motifs—on either the coding or template strand—is achieved strictly through synonymous substitutions, thereby preserving the structural and functional integrity of the encoded translated protein.