The PAXT connection is a modifier of rare codon-enriched protein expression

However, there are an increasing number of examples whereby rare codon-enriched genes are paradoxically highly expressed, suggestive of mechanisms to overcome the poor expression imposed by rare codons.

To identify codon-dependent modifiers, we screen a targeted sgRNA library for genes that, when inactivated, increase the expression of rare versus common codon-enriched fluorescent reporters. This identifies the PAXT connection, a nuclear complex that targets transcripts to the exosome for degradation. Targeted loss of a PAXT component leads to a small but preferential increase in mRNA levels and stability, and a more pronounced increase in protein expression of rare compared to common codon-enriched reporters.