Adaptor protein complex-1 (AP-1) is recruited by the HEATR5 protein Laa1 and its co-factor Laa2 in yeast

• DOI: 10.1074/jbc.ra118.005253
• Publication Date: 2018-12-06T20:55:53Z
• Authors: Christopher J. Zy...; Sagar Lahiri; Fatima T. Javed; Jorge Y. Martínez...; Justin W. Trowbridge; Mara C. Duncan
• Keywords: DNA-Binding Proteins; 0303 health sciences; 03 medical and health sciences; Phenotype; Saccharomyces cerevisiae Proteins; Microscopy, Fluorescence; Adaptor Protein Complex 1; Computational Biology; Saccharomyces cerevisiae; Adaptor Proteins, Signal Transducing

Cellular membrane trafficking mediated by the clathrin adaptor protein complex-1 (AP-1) is important for the proper composition and function of organelles of the endolysosomal system. Normal AP-1 function requires proteins of the HEAT repeat-containing 5 (HEATR5) family. Although HEATR5 proteins were first identified based on their ability to interact with AP-1, the functional significance of this interaction was unknown. We used bioinformatics-based phenotypic profiling and information from genome-wide fluorescence microscopy studies in the budding yeast Saccharomyces cerevisiae to identify a protein, Laa2, that mediates the interaction between AP-1 and the yeast HEATR5 protein Laa1. Further characterization of Laa2 revealed that it binds to both Laa1 and AP-1. Laa2 contains a motif similar to the characterized γ-ear-binding sites found in other AP-1-binding proteins. This motif in Laa2 is essential for the Laa1-AP-1 interaction. Moreover, mutation of this motif disrupted AP-1 localization and function and caused effects similar to mutations that remove the γ-ear of AP-1. These results indicate that Laa2 mediates the interaction between Laa1 and AP-1 and reveal that this interaction promotes the stable association of AP-1 with membranes in yeast.