title: pH-dependent binding of the Epsin ENTH domain and the AP180 ANTH domain to PI(4,5)P2-containing bilayers.
abstract: Epsin and AP180 are essential components of the endocytotic machinery, which controls internalization of protein receptors and other macromolecules at the cell surface. Epsin and AP180 are recruited to the plasma membrane by their structurally and functionally related N-terminal ENTH and ANTH domains that specifically recognize PtdIns(4,5)P2. Here, we show that membrane anchoring of the ENTH and ANTH domains is regulated by the acidic environment. Lowering the pH enhances PtdIns(4,5)P2 affinity of the ENTH and ANTH domains reinforcing their association with lipid vesicles and monolayers. The pH dependency is due to the conserved histidine residues of the ENTH and ANTH domains, protonation of which is necessary for the strong PtdIns(4,5)P2 recognition, as revealed by liposome binding, surface plasmon resonance, NMR, monolayer surface tension and mutagenesis experiments. The pH sensitivity of the ENTH and ANTH domains is reminiscent to the pH dependency of the FYVE domain suggesting a common regulatory mechanism of membrane anchoring by a subset of the PI-binding domains.
authors.affiliation: Department of Pharmacology, University of Colorado Health Sciences Center, Aurora, CO 80045, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hom
authors.forename: Mohsin
authors.initials: M
authors.lastname: Vora
authors.forename: Maryann
authors.initials: M
authors.lastname: Regner
authors.forename: Oksana M
authors.initials: OM
authors.lastname: Subach
authors.forename: Wonhwa
authors.initials: W
authors.lastname: Cho
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Verkhusha
authors.forename: Robert V
authors.initials: RV
authors.lastname: Stahelin
authors.forename: Tatiana G
authors.initials: TG
authors.lastname: Kutateladze
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D034041:Monomeric Clathrin Assembly Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D016415:Sequence Alignment