Arf1p, Chs5p and the ChAPs are required for export of specialized cargo from the Golgi.
In Saccharomyces cerevisiae, the synthesis of chitin is temporally and spatially regulated through the transport of Chs3p (chitin synthase III) to the plasma membrane in the bud neck region. Traffic of Chs3p from the trans-Golgi network (TGN)/early endosome to the plasma membrane requires the function of Chs5p and Chs6p. Chs6p belongs to a family of four proteins that we have named ChAPs for Chs5p-Arf1p-binding Proteins. Here, we show that all ChAPs physically interact not only with Chs5p but also with the small GTPase Arf1p. A short sequence at the C-terminus of the ChAPs is required for protein function and the ability to bind to Chs5p. Simultaneous disruption of two members, Deltabud7 and Deltabch1, phenocopies a Deltachs6 or Deltachs5 deletion with respect to Chs3p transport. Moreover, the ChAPs interact with each other and can form complexes. In addition, they are all at least partially localized to the TGN in a Chs5p-dependent manner. Most importantly, several ChAPs can interact physically with Chs3p. We propose that the ChAPs facilitate export of cargo out of the Golgi.
Friedrich Miescher Laboratorium, Max Planck Gesellschaft, Tübingen, Germany.
Mark
M
Trautwein
Christina
C
Schindler
Robert
R
Gauss
Jörn
J
Dengjel
Enno
E
Hartmann
Anne
A
Spang
D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism*; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002686:Chitin / Q000096:biosynthesis*; D002687:Chitin Synthase / Q000378:metabolism*; D002846:Chromatography, Affinity; D006056:Golgi Apparatus / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D021601:trans-Golgi Network / Q000378:metabolism
D033942:Adaptor Proteins, Vesicular Transport; C509470:CHS6 protein, S cerevisiae; D002352:Carrier Proteins; D029701:Saccharomyces cerevisiae Proteins; D002686:Chitin; C069390:CHS3 protein, S cerevisiae; C491360:CHS5 protein, S cerevisiae; D002687:Chitin Synthase; D020823:ADP-Ribosylation Factor 1