Structural basis for the binding of tryptophan-based motifs by δ-COP.

TitleStructural basis for the binding of tryptophan-based motifs by δ-COP.
Publication TypeJournal Article
Year of Publication2015
AuthorsSuckling, RJ, Poon, PPhi, Travis, SM, Majoul, IV, Hughson, FM, Evans, PR, Duden, R, Owen, DJ
JournalProc Natl Acad Sci U S A
Date Published2015 Nov 17
KeywordsAmino Acid Motifs, Calorimetry, Indirect, Cathepsin A, Coatomer Protein, COP-Coated Vesicles, DNA-Binding Proteins, GTPase-Activating Proteins, Protein Binding, Protein Structure, Tertiary, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Tryptophan

<p>Coatomer consists of two subcomplexes: the membrane-targeting, ADP ribosylation factor 1 (Arf1):GTP-binding βγδζ-COP F-subcomplex, which is related to the adaptor protein (AP) clathrin adaptors, and the cargo-binding αβ'ε-COP B-subcomplex. We present the structure of the C-terminal μ-homology domain of the yeast δ-COP subunit in complex with the WxW motif from its binding partner, the endoplasmic reticulum-localized Dsl1 tether. The motif binds at a site distinct from that used by the homologous AP μ subunits to bind YxxΦ cargo motifs with its two tryptophan residues sitting in compatible pockets. We also show that the Saccharomyces cerevisiae Arf GTPase-activating protein (GAP) homolog Gcs1p uses a related WxxF motif at its extreme C terminus to bind to δ-COP at the same site in the same way. Mutations designed on the basis of the structure in conjunction with isothermal titration calorimetry confirm the mode of binding and show that mammalian δ-COP binds related tryptophan-based motifs such as that from ArfGAP1 in a similar manner. We conclude that δ-COP subunits bind Wxn(1-6)[WF] motifs within unstructured regions of proteins that influence the lifecycle of COPI-coated vesicles; this conclusion is supported by the observation that, in the context of a sensitizing domain deletion in Dsl1p, mutating the tryptophan-based motif-binding site in yeast causes defects in both growth and carboxypeptidase Y trafficking/processing.</p>

Alternate JournalProc Natl Acad Sci U S A
PubMed ID26578768
PubMed Central IDPMC4655537
Grant List100140 / / Wellcome Trust / United Kingdom
MC_U105178845 / MRC_ / Medical Research Council / United Kingdom
/ / Canadian Institutes of Health Research / Canada
T32 GM007388 / GM / NIGMS NIH HHS / United States
R01 GM071574 / GM / NIGMS NIH HHS / United States
GM071574 / GM / NIGMS NIH HHS / United States
U105178845 / / Medical Research Council / United Kingdom
090909 / / Wellcome Trust / United Kingdom