title: Structure and function of the PLAA/Ufd3-p97/Cdc48 complex.
abstract: PLAA (ortholog of yeast Doa1/Ufd3, also know as human PLAP or phospholipase A2-activating protein) has been implicated in a variety of disparate biological processes that involve the ubiquitin system. It is linked to the maintenance of ubiquitin levels, but the mechanism by which it accomplishes this is unclear. The C-terminal PUL (PLAP, Ufd3p, and Lub1p) domain of PLAA binds p97, an AAA ATPase, which among other functions helps transfer ubiquitinated proteins to the proteasome for degradation. In yeast, loss of Doa1 is suppressed by altering p97/Cdc48 function indicating that physical interaction between PLAA and p97 is functionally important. Although the overall regions of interaction between these proteins are known, the structural basis has been unavailable. We solved the high resolution crystal structure of the p97-PLAA complex showing that the PUL domain forms a 6-mer Armadillo-containing domain. Its N-terminal extension folds back onto the inner curvature forming a deep ridge that is positively charged with residues that are phylogenetically conserved. The C terminus of p97 binds in this ridge, where the side chain of p97-Tyr(805), implicated in phosphorylation-dependent regulation, is buried. Expressed in doa1Delta null cells, point mutants of the yeast ortholog Doa1 that disrupt this interaction display slightly reduced ubiquitin levels, but unlike doa1Delta null cells, showed only some of the growth phenotypes. These data suggest that the p97-PLAA interaction is important for a subset of PLAA-dependent biological processes and provides a framework to better understand the role of these complex molecules in the ubiquitin system.
authors.affiliation: Structural Genomics Consortium, Department of Physiology, University of Toronto, Toronto, Ontario M5G 1L7,Canada.
authors.forename: Liyan
authors.initials: L
authors.lastname: Qiu
authors.forename: Natasha
authors.initials: N
authors.lastname: Pashkova
authors.forename: John R
authors.initials: JR
authors.lastname: Walker
authors.forename: Stanley
authors.initials: S
authors.lastname: Winistorfer
authors.forename: Abdellah
authors.initials: A
authors.lastname: Allali-Hassani
authors.forename: Masato
authors.initials: M
authors.lastname: Akutsu
authors.forename: Robert
authors.initials: R
authors.lastname: Piper
authors.forename: Sirano
authors.initials: S
authors.lastname: Dhe-Paganon
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005454:Fluorescence Polarization; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D000074405:Valosin Containing Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C099944:DOA1 protein, S cerevisiae; D009687:Nuclear Proteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; C055324:phospholipase A2-activating protein; D000251:Adenosine Triphosphatases; C404942:p97 ATPase; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein