title: Structural basis for acidic-cluster-dileucine sorting-signal recognition by VHS domains.
abstract: Specific sorting signals direct transmembrane proteins to the compartments of the endosomal-lysosomal system. Acidic-cluster-dileucine signals present within the cytoplasmic tails of sorting receptors, such as the cation-independent and cation-dependent mannose-6-phosphate receptors, are recognized by the GGA (Golgi-localized, gamma-ear-containing, ADP-ribosylation-factor-binding) proteins. The VHS (Vps27p, Hrs and STAM) domains of the GGA proteins are responsible for the highly specific recognition of these acidic-cluster-dileucine signals. Here we report the structures of the VHS domain of human GGA3 complexed with signals from both mannose-6-phosphate receptors. The signals bind in an extended conformation to helices 6 and 8 of the VHS domain. The structures highlight an Asp residue separated by two residues from a dileucine sequence as critical recognition elements. The side chains of the Asp-X-X-Leu-Leu sequence interact with subsites consisting of one electropositive and two shallow hydrophobic pockets, respectively. The rigid spatial alignment of the three binding subsites leads to high specificity.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Saurav
authors.initials: S
authors.lastname: Misra
authors.forename: Rosa
authors.initials: R
authors.lastname: Puertollano
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kato
authors.forename: Juan S
authors.initials: JS
authors.lastname: Bonifacino
authors.forename: James H
authors.initials: JH
authors.lastname: Hurley
mesh_terms: D020727:ADP-Ribosylation Factors / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004926:Escherichia coli; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007930:Leucine / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017527:Receptor, IGF Type 2 / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D020798:Two-Hybrid System Techniques
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; C407306:GGA adaptor proteins; D017527:Receptor, IGF Type 2; D020727:ADP-Ribosylation Factors; D007930:Leucine