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.

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 inArabidopsis thalianafor 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 thetrans-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. Themin7/ben1mutant phenocopied the mild root developmental defects and latrunculin B hypersensitivity ofhlb1, and analyses of ahlb1/ min7/ben1double mutant showed thathlb1andmin7/ben1operate 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 theTGN/EEat the intersection of the exocytic and endocytic pathways in plants.

KEYWORDS: {{ getKeywords(articleDetailText.words) }}