7q4p
U2 snRNP after ATP-dependent remodelling
Structural highlights
FunctionSF3A2_HUMAN Subunit of the splicing factor SF3A required for 'A' complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence (BPS) in pre-mRNA. Sequence independent binding of SF3A/SF3B complex upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA. May also be involved in the assembly of the 'E' complex. Publication Abstract from PubMedRecognition of the intron branch site (BS) by the U2 small nuclear ribonucleoprotein (snRNP) is a critical event during spliceosome assembly. In mammals, BS sequences are poorly conserved, and unambiguous intron recognition cannot be achieved solely through a base-pairing mechanism. We isolated human 17S U2 snRNP and reconstituted in vitro its adenosine 5 -triphosphate (ATP)-dependent remodeling and binding to the pre-messenger RNA substrate. We determined a series of high-resolution (2.0 to 2.2 angstrom) structures providing snapshots of the BS selection process. The substrate-bound U2 snRNP shows that SF3B6 stabilizes the BS:U2 snRNA duplex, which could aid binding of introns with poor sequence complementarity. ATP-dependent remodeling uncoupled from substrate binding captures U2 snRNA in a conformation that competes with BS recognition, providing a selection mechanism based on branch helix stability. Structural basis of branch site recognition by the human spliceosome.,Tholen J, Razew M, Weis F, Galej WP Science. 2022 Jan 7;375(6576):50-57. doi: 10.1126/science.abm4245. Epub 2021 Nov , 25. PMID:34822310[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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