title: HLB1 Is a Tetratricopeptide Repeat Domain-Containing Protein That Operates at the Intersection of the Exocytic and Endocytic Pathways at the TGN/EE in Arabidopsis.
abstract: The endomembrane system plays essential roles in plant development, but the proteome responsible for its function and organization remains largely uncharacterized in plants. Here, we identified and characterized the HYPERSENSITIVE TO LATRUNCULIN B1 (HLB1) protein isolated through a forward-genetic screen in Arabidopsis thaliana for mutants with heightened sensitivity to actin-disrupting drugs. HLB1 is a plant-specific tetratricopeptide repeat domain-containing protein of unknown function encoded by a single Arabidopsis gene. HLB1 associated with the trans-Golgi network (TGN)/early endosome (EE) and tracked along filamentous actin, indicating that it could link post-Golgi traffic with the actin cytoskeleton in plants. HLB1 was found to interact with the ADP-ribosylation-factor guanine nucleotide exchange factor, MIN7/BEN1 (HOPM INTERACTOR7/BREFELDIN A-VISUALIZED ENDOCYTIC TRAFFICKING DEFECTIVE1) by coimmunoprecipitation. The min7/ben1 mutant phenocopied the mild root developmental defects and latrunculin B hypersensitivity of hlb1, and analyses of ahlb1/ min7/ben1 double mutant showed that hlb1 and min7/ben1 operate in common genetic pathways. Based on these data, we propose that HLB1 together with MIN7/BEN1 form a complex with actin to modulate the function of the TGN/EE at the intersection of the exocytic and endocytic pathways in plants.
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
authors.forename: J Alan
authors.initials: JA
authors.lastname: Sparks
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
authors.forename: Taegun
authors.identifier: http://orcid.org/0000-0002-0205-8535
authors.initials: T
authors.lastname: Kwon
authors.affiliation: Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
authors.forename: Luciana
authors.initials: L
authors.lastname: Renna
authors.affiliation: Computing Services Department, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
authors.forename: Fuqi
authors.initials: F
authors.lastname: Liao
authors.affiliation: Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
authors.forename: Federica
authors.initials: F
authors.lastname: Brandizzi
authors.affiliation: Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 eblancaflor@noble.org.
authors.forename: Elison B
authors.identifier: http://orcid.org/0000-0001-6115-9670
authors.initials: EB
authors.lastname: Blancaflor
mesh_terms: D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D005089:Exocytosis; D006056:Golgi Apparatus / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D021381:Protein Transport; D021601:trans-Golgi Network / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C512008:At3g43300 protein, Arabidopsis; D020662:Guanine Nucleotide Exchange Factors; C000613187:HLB1 protein, Arabidopsis; D008840:Microfilament Proteins; D020727:ADP-Ribosylation Factors