title: Ubiquitin interactions of NZF zinc fingers.
abstract: Ubiquitin (Ub) functions in many different biological pathways, where it typically interacts with proteins that contain modular Ub recognition domains. One such recognition domain is the Npl4 zinc finger (NZF), a compact zinc-binding module found in many proteins that function in Ub-dependent processes. We now report the solution structure of the NZF domain from Npl4 in complex with Ub. The structure reveals that three key NZF residues (13TF14/M25) surrounding the zinc coordination site bind the hydrophobic 'Ile44' surface of Ub. Mutations in the 13TF14/M25 motif inhibit Ub binding, and naturally occurring NZF domains that lack the motif do not bind Ub. However, substitution of the 13TF14/M25 motif into the nonbinding NZF domain from RanBP2 creates Ub-binding activity, demonstrating the versatility of the NZF scaffold. Finally, NZF mutations that inhibit Ub binding by the NZF domain of Vps36/ESCRT-II also inhibit sorting of ubiquitylated proteins into the yeast vacuole. Thus, the NZF is a versatile protein recognition domain that is used to bind ubiquitylated proteins during vacuolar protein sorting, and probably many other biological processes.
authors.affiliation: Department of Biochemistry, University of Utah, Salt Lake City, UT, USA. alam@wsu.edu
authors.forename: Steven L
authors.initials: SL
authors.lastname: Alam
authors.forename: Ji
authors.initials: J
authors.lastname: Sun
authors.forename: Marielle
authors.initials: M
authors.lastname: Payne
authors.forename: Brett D
authors.initials: BD
authors.lastname: Welch
authors.forename: B Kelly
authors.initials: BK
authors.lastname: Blake
authors.forename: Darrell R
authors.initials: DR
authors.lastname: Davis
authors.forename: Hemmo H
authors.initials: HH
authors.lastname: Meyer
authors.forename: Scott D
authors.initials: SD
authors.lastname: Emr
authors.forename: Wesley I
authors.initials: WI
authors.lastname: Sundquist
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017433:Protein Structure, Secondary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers
chemical_list: D002352:Carrier Proteins; D046912:Multiprotein Complexes; C495985:Nploc4 protein, rat; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin