SART3 associates with a post-splicing complex

SART3 is a multifunctional protein that acts in several steps of gene expression, including assembly and recycling of the spliceosomal U4/ U6 small nuclear ribonucleoprotein particle (snRNP). In this work, we provide evidence that SART3 associates via its N-terminal HAT domain with the 12S U2 snRNP. Further analysis showed that SART3 associates with the post-splicing complex containing U2 and U5 snRNP components. In addition, we observed an interaction between SART3 and the RNA helicase DHX15, which disassembles post-splicing complexes. Based on our data, we propose a model that SART3 associates via its N-terminal HAT domain with the post-splicing complex, where it interacts with U6 snRNA to protect it and to initiate U6 snRNA recycling before a next round of splicing.

Automated summary

SART3 is a multifunctional protein involved in multiple steps of gene expression, including the assembly and recycling of the spliceosomal U4/U6 snRNP. This study demonstrates that SART3 interacts with the 12S U2 snRNP through its N-terminal HAT domain. Furthermore, it associates with the post-splicing complex containing U2 and U5 snRNP components, and also interacts with the RNA helicase DHX15. The proposed model suggests that SART3 protects and initiates the recycling of U6 snRNA in the post-splicing complex.