5wsg
From Proteopedia
Cryo-EM structure of the Catalytic Step II spliceosome (C* complex) at 4.0 angstrom resolution
Structural highlights
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Function[RU2A_YEAST] Involved in pre-mRNA splicing. Associates to U2 snRNA in a MSL1 dependent manner and is required for normal accumulation of U2 snRNA. Required for the spliceosome assembly and the efficient addition of U2 snRNP onto the pre-mRNA.[1] [PRP17_YEAST] May function in the second step of pre-mRNA splicing. Regulatory protein involved in replication and mitotic spindle formation and/or maintenance. Required for initiation and completion of S-phase and for initiation and completion of DNA replication. Might be required for the maintenance of microtubules. Essential only at elevated temperatures. [CWC2_YEAST] Involved in the first step of pre-mRNA splicing. Required for cell growth and cell cycle control. Plays a role in the levels of the U1, U4, U5 and U6 snRNAs and the maintenance of the U4/U6 snRNA complex. May provide the link between the "nineteen complex" NTC spliceosome protein complex and the spliceosome through the U6 snRNA. Associates predominantly with U6 snRNAs in assembled active spliceosomes. Binds directly to the internal stem-loop (ISL) domain of the U6 snRNA and to the pre-mRNA intron near the 5' splice site during the activation and catalytic phases of the spliceosome cycle. Binds also to U1, U4, U5 and U6 snRNAs and to pre-mRNAs, in vitro. Is not required for the Prp2-mediated remodeling of the activated spliceosome.[2] [3] [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. [CEF1_YEAST] Involved in pre-mRNA splicing and cell cycle control. Required for the binding of the NTC complex (or PRP19-associated complex) components to the spliceosome to mediate conformational rearrangement or to stabilize the structure of the spliceosome after U4 snRNA dissociation, which leads to spliceosome maturation. Its absence leads to an arrest of the cell cycle, possibly due to the inefficient splicing of TUB1.[4] [5] [6] [7] [SN114_YEAST] Component of the U5 snRNP complex required for pre-mRNA splicing. Binds GTP. [PRP8_YEAST] Required for pre-spliceosome formation, which is the first step of pre-mRNA splicing. This protein is associated with snRNP U5. Has a role in branch site-3' splice site selection. Associates with the branch site-3' splice 3'-exon region. Also has a role in cell cycle.[8] [9] [10] [11] [CLF1_YEAST] Involved in pre-mRNA splicing and cell cycle progression. Required for the spliceosome assembly by promoting the functional integration of the U4/U6.U5 tri-snRNP particle into the U1-, U2-dependent pre-spliceosome. Also recruits PRP19 to the spliceosome, as a component of the NTC complex (or PRP19-associated complex). The association of the NTC complex to the spliceosome mediates conformational rearrangement or stabilizes the structure of the spliceosome after U4 snRNA dissociation, which leads to spliceosome maturation. Required for initiation of the DNA replication by binding the RNA replication origins, probably through its interaction with the origin recognition complex (ORC).[12] [13] [14] [15] [16] [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. [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. [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.[17] [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.[18] [19] [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. [CWC22_YEAST] May be involved in pre-mRNA splicing. [MSL1_YEAST] Involved in pre-mRNA splicing. This protein is associated with snRNP U2. It binds stem loop IV of U2 snRNA.[20] [PRP18_YEAST] Component of the U4/U5/U6 snRNP, binding principally to the u5 snRNP. It is not absolutely required for the second step of pre-mRNA splicing at low temperatures but is required at higher temperatures. It may stabilize a particular conformation of the U5 snRNP or orient the U5 snRNP within the U4/U5/U6 snRNP or within the spliceosome. [PRP19_YEAST] Involved in pre-mRNA splicing. Acts a central component of the NTC complex (or PRP19-associated complex) that associates to the spliceosome to mediate conformational rearrangement or to stabilize the structure of the spliceosome after U4 snRNA dissociation, which leads to spliceosome maturation. Involved in DNA repair. [SN309_YEAST] Involved in pre-mRNA splicing by stabilizing the NTC (or PRP19-associated complex). As a component of the NTC complex, associates to the spliceosome to mediate conformational rearrangement or to stabilize the structure of the spliceosome after U4 snRNA dissociation, which leads to spliceosome maturation.[21] [22] [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.[23] [24] [SLT11_YEAST] Involved in pre-mRNA splicing. Facilitates the cooperative formation of U2/U6 helix II in association with stem II in the spliceosome. Binds to RNA.[25] [26] [CWC21_YEAST] Involved in pre-mRNA splicing. May function at or prior to the first catalytic step of splicing at the catalytic center of the spliceosome, together with ISY1. May do so by stabilizing the catalytic center or the position of the RNA substrate.[27] [28] [BUD31_YEAST] Involved in pre-mRNA splicing. Important for bud site selection. [CWC15_YEAST] Involved in pre-mRNA splicing. [PRP46_YEAST] Involved in pre-mRNA splicing. May also be required for cell cycle progression at G2/M (By similarity).[29] [PRP16_YEAST] Influences the fidelity of branchpoint recognition in yeast splicing. This is RNA-dependent ATPase which is essential for viability. It may mediate one of the many ATP-requiring steps of spliceosome assembly and that accuracy of branchpoint recognition may be coupled to ATP binding and/or hydrolysis.[30] [SYF2_YEAST] Involved in pre-mRNA splicing and cell cycle control. As a component of the NTC complex (or PRP19-associated complex), associates to the spliceosome to mediate conformational rearrangement or to stabilize the structure of the spliceosome after U4 snRNA dissociation, which leads to spliceosome maturation. The cell cycle arrest of SYF2 defective cells may be due to the inefficient splicing of TUB1.[31] [32] [33] [PRP45_YEAST] Involved in pre-mRNA splicing. Associated with the spliceosome throughout the splicing reactions, until after the second catalytic step.[34] [35] Publication Abstract from PubMedEach cycle of precursor messenger RNA (pre-mRNA) splicing comprises two sequential reactions, first freeing the 5' exon and generating an intron lariat-3' exon and then ligating the two exons and releasing the intron lariat. The second reaction is executed by the step II catalytically activated spliceosome (known as the C* complex). Here, we present the cryo-electron microscopy structure of a C* complex from Saccharomyces cerevisiae at an average resolution of 4.0 angstroms. Compared with the preceding spliceosomal complex (C complex), the lariat junction has been translocated by 15 to 20 angstroms to vacate space for the incoming 3'-exon sequences. The step I splicing factors Cwc25 and Yju2 have been dissociated from the active site. Two catalytic motifs from Prp8 (the 1585 loop and the beta finger of the ribonuclease H-like domain), along with the step II splicing factors Prp17 and Prp18 and other surrounding proteins, are poised to assist the second transesterification. These structural features, together with those reported for other spliceosomal complexes, yield a near-complete mechanistic picture on the splicing cycle. Structure of a yeast step II catalytically activated spliceosome.,Yan C, Wan R, Bai R, Huang G, Shi Y Science. 2017 Jan 13;355(6321):149-155. doi: 10.1126/science.aak9979. Epub 2016, Dec 15. PMID:27980089[36] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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