TY - JOUR TI - Crystal structure of human U1 snRNP, a small nuclear ribonucleoprotein particle, reveals the mechanism of 5′ splice site recognition AU - Kondo, Yasushi AU - Oubridge, Chris AU - van Roon, Anne-Marie M AU - Nagai, Kiyoshi A2 - Nilsen, Timothy VL - 4 PY - 2015 DA - 2015/01/02 SP - e04986 C1 - eLife 2015;4:e04986 DO - 10.7554/eLife.04986 UR - https://doi.org/10.7554/eLife.04986 AB - U1 snRNP binds to the 5′ exon-intron junction of pre-mRNA and thus plays a crucial role at an early stage of pre-mRNA splicing. We present two crystal structures of engineered U1 sub-structures, which together reveal at atomic resolution an almost complete network of protein–protein and RNA-protein interactions within U1 snRNP, and show how the 5′ splice site of pre-mRNA is recognised by U1 snRNP. The zinc-finger of U1-C interacts with the duplex between pre-mRNA and the 5′-end of U1 snRNA. The binding of the RNA duplex is stabilized by hydrogen bonds and electrostatic interactions between U1-C and the RNA backbone around the splice junction but U1-C makes no base-specific contacts with pre-mRNA. The structure, together with RNA binding assays, shows that the selection of 5′-splice site nucleotides by U1 snRNP is achieved predominantly through basepairing with U1 snRNA whilst U1-C fine-tunes relative affinities of mismatched 5′-splice sites. KW - pre-mRNA splicing KW - crystallography KW - spliceosome KW - U1 snRNP KW - 5′ splice site JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -