4wal
Crystal structure of selenomethionine Msl5 protein in complex with RNA at 2.2 A
Structural highlights
FunctionBBP_YEAST Required for pre-spliceosome formation, which is the first step of pre-mRNA splicing. 2 commitment complexes, CC1 and CC2, have been defined. CC1 is a basal complex dependent only on the 5'-splice site. CC2 is a complex of lower mobility and is dependent on a branchpoint as well as a 5'-splice site region. This protein is involved in CC2 formation where it binds to the snRNP U1-associated protein PRP40, bridging the U1 snRNP-associated 5'-splice site and the MSL5-associated branch point 3' intron splice site. Involved in nuclear retention of pre-mRNA.[1] [2] [3] Publication Abstract from PubMedSaccharomyces cerevisiae Msl5 orchestrates spliceosome assembly by binding the intron branchpoint sequence 5'-UACUAAC and, with its heterodimer partner protein Mud2, establishing cross intron-bridging interactions with the U1 snRNP at the 5' splice site. Here we define the central Msl5 KH-QUA2 domain as sufficient for branchpoint RNA recognition. The 1.8 A crystal structure of Msl5-(KH-QUA2) bound to the branchpoint highlights an extensive network of direct and water-mediated protein-RNA and intra-RNA atomic contacts at the interface that illuminate how Msl5 recognizes each nucleobase of the UACUAAC element. The Msl5 structure rationalizes a large body of mutational data and inspires new functional studies herein, which reveal how perturbations of the Msl5.RNA interface impede the splicing of specific yeast pre-mRNAs. We also identify interfacial mutations in Msl5 that bypass the essentiality of Sub2, a DExD-box ATPase implicated in displacing Msl5 from the branchpoint in exchange for the U2 snRNP. These studies establish an atomic resolution framework for understanding splice site selection and early spliceosome dynamics. Structural basis for recognition of intron branchpoint RNA by yeast Msl5 and selective effects of interfacial mutations on splicing of yeast pre-mRNAs.,Jacewicz A, Chico L, Smith P, Schwer B, Shuman S RNA. 2015 Jan 13. PMID:25587180[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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