title: Structural constraints on autoprocessing of the human nucleoporin Nup98.
abstract: Nucleoporin Nup98, a 98-kDa protein component of the nuclear pore complex, plays an important role in both protein and RNA transport. During its maturation process, Nup98 undergoes post-translational autoproteolysis, which is critical for targeting to the NPC. Here we present high-resolution crystal structures of the C-terminal autoproteolytic domains of Nup98 (2.3 A for the wild type and 1.9 A for the S864A precursor), and propose a detailed autoproteolysis mechanism through an N-O acyl shift. Structural constraints are found at the autocleavage site, and could thus provide a driving force for autocleavage at the scissile peptide bond. Such structural constraints appear to be generated, at least in part, by anchoring a conserved phenylalanine side chain into a highly conserved hydrophobic pocket at the catalytic site. Our high-resolution crystal structures also reveal that three highly conserved residues, Tyr866, Gly867, and Leu868, provide most of the interactions between the autoproteolytic domain and the C-terminal tail. These results suggest that Nup98 may represent a new subtype of protein that utilizes autoprocessing to control biogenesis pathways and intracellular translocation.
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118-2526, USA.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Sun
authors.forename: Hwai-Chen
authors.initials: HC
authors.lastname: Guo
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary
chemical_list: D028861:Nuclear Pore Complex Proteins; C465451:Nup98 protein, human