6n7r | pdb_00006n7r
Saccharomyces cerevisiae spliceosomal E complex (ACT1)
Structural highlights
Function[SMD1_YEAST] Involved in pre-mRNA splicing. Binds snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. Also binds telomerase RNA and is required for its accumulation.[1] [2] [SNU56_YEAST] Component of the U1 snRNP particle, which recognizes and binds the 5'-splice site of pre-mRNA. Together with other non-snRNP factors, U1 snRNP forms the spliceosomal commitment complex, that targets pre-mRNA to the splicing pathway. [RU1C_YEAST] Component of the spliceosomal U1 snRNP, which is essential for recognition of the pre-mRNA 5' splice-site and the subsequent assembly of the spliceosome. YHC1/U1-C is directly involved in initial 5' splice-site recognition for both constitutive and regulated alternative splicing. The interaction with the 5' splice-site seems to precede base-pairing between the pre-mRNA and the U1 snRNA. Stimulates commitment or early (E) complex formation by stabilizing the base pairing of the 5' end of the U1 snRNA and the 5' splice-site region.[3] [4] [5] [RU17_YEAST] Involved in nuclear mRNA splicing. [RUXG_YEAST] Involved in pre-mRNA splicing. Binds snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. [SMD3_YEAST] Involved in pre-mRNA splicing. Binds snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. Also binds telomerase RNA and is required for its accumulation.[6] [7] [NAM8_YEAST] Acts as a suppressor of mitochondrial splicing deficiencies when overexpressed. Could be a non-essential component of the mitochondrial splicing machinery. [RU1A_YEAST] Involved in nuclear mRNA splicing. The principal role of the U1A is to help fold or maintain U1 RNA in an active configuration. It is the first snRNP to interact with pre-mRNA. This interaction is required for the subsequent binding of U2 snRNP and the U4/U6/U5 tri-snRNP.[8] [9] [LUC7_YEAST] Component of the U1 snRNP particle, which recognizes and binds the 5'-splice site of pre-mRNA. Together with other non-snRNP factors, U1 snRNP forms the spliceosomal commitment complex, that targets pre-mRNA to the splicing pathway.[10] [11] [SMD2_YEAST] Involved in pre-mRNA splicing. Binds snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. [RUXE_YEAST] Involved in pre-mRNA splicing. Binds and is required for the stability of snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. Involved in cap modification.[12] [RUXF_YEAST] Involved in pre-mRNA splicing. Binds snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. [SNU71_YEAST] Component of the U1 snRNP particle, which recognizes and binds the 5'-splice site of pre-mRNA. Together with other non-snRNP factors, U1 snRNP forms the spliceosomal commitment complex, that targets pre-mRNA to the splicing pathway.[13] [PRP42_YEAST] Essential component of the U1 snRNP particle, which recognizes and binds the 5'-splice site of pre-mRNA. Together with other non-snRNP factors, U1 snRNP forms the spliceosomal commitment complex, that targets pre-mRNA to the splicing pathway. U1 snRNP is cotranscriptionally recruited to intron-containing genes. Required for U1 snRNP biogenesis.[14] [15] [RSMB_YEAST] Involved in pre-mRNA splicing. Binds snRNA U1, U2, U4 and U5 which contain a highly conserved structural motif called the Sm binding site. [PRP39_YEAST] Function prior to stable branch point recognition by the U1 snRNP particle to facilitate or stabilize the U1 snRNP/5'-splice site interaction. Has a direct role in the assembly or function of a catalytically active spliceosome. Publication Abstract from PubMedThe molecular mechanisms of exon definition and back-splicing are fundamental unanswered questions in pre-mRNA splicing. Here we report cryo-electron microscopy structures of the yeast spliceosomal E complex assembled on introns, providing a view of the earliest event in the splicing cycle that commits pre-mRNAs to splicing. The E complex architecture suggests that the same spliceosome can assemble across an exon, and that it either remodels to span an intron for canonical linear splicing (typically on short exons) or catalyses back-splicing to generate circular RNA (on long exons). The model is supported by our experiments, which show that an E complex assembled on the middle exon of yeast EFM5 or HMRA1 can be chased into circular RNA when the exon is sufficiently long. This simple model unifies intron definition, exon definition, and back-splicing through the same spliceosome in all eukaryotes and should inspire experiments in many other systems to understand the mechanism and regulation of these processes. A unified mechanism for intron and exon definition and back-splicing.,Li X, Liu S, Zhang L, Issaian A, Hill RC, Espinosa S, Shi S, Cui Y, Kappel K, Das R, Hansen KC, Zhou ZH, Zhao R Nature. 2019 Sep;573(7774):375-380. doi: 10.1038/s41586-019-1523-6. Epub 2019 Sep, 4. PMID:31485080[16] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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