The 1.9Â Ã crystal structure of Prp20p from Saccharomyces cerevisiae and its binding properties to Gsp1p and histones

Prp20p is the homolog of mammalian RCC1 (regulator of chromosome condensation 1) in Saccharomyces cerevisiae, which acts as the guanine nucleotide exchange factor (GEF) for Gsp1p (yeast Ran). Prp20p plays multiple roles in mRNA metabolism, nucleocytoplasmic transport and mitosis regulation. Prp20p also functions as a linker between chromatin and nuclear pore complex (NPC) which regulates the NPC-mediated boundary activity (BA). Prp20p contains an N-terminal nuclear localization signal (NLS) and a typical RCC1-like domain (RLD). Here we present the 1.9 Å crystal structure of the RCC1-like domain of Prp20p, which exhibits a classical seven-bladed β-propeller. We also proved that the additional β-wedge in Prp20p is essential for the interaction between Prp20p and Gsp1p. Based on this structure, we built a complex model of Prp20p and Gsp1p which was optimized by molecular dynamics (MD) simulations. Our model reveals that Prp20p and RCC1 share similar Ran GTPase binding mode. In addition, we also studied the histone-binding property of Prp20p in vitro.