The GAP domain and the SNARE, coatomer and cargo interaction region of the ArfGAP2/3 Glo3 are sufficient for Glo3 function.
The ArfGAP Glo3 is required for coat protein I vesicle generation in the Golgi-endoplasmic reticulum (ER) shuttle. The best-understood role of Glo3 is the stimulation of the GTPase activity of Arf1. In this study, we characterized functional domains of the ArfGAP Glo3 and identified an interaction interface for coatomer, SNAREs and cargo in the central region of Glo3 (BoCCS region). The GAP domain together with the BoCCS region is necessary and sufficient for all vital Glo3 functions. Expression of a truncated Glo3 lacking the GAP domain results in a dominant negative growth phenotype in glo3Delta cells at 37 degrees C. This phenotype was alleviated by mutating either the BoCCS region or the Glo3 regulatory motif (GRM), or by overexpression of ER-Golgi SNAREs or the ArfGAP Gcs1. The GRM is not essential for Glo3 function; it may act as an intrinsic sensor coupling GAP activity to SNARE binding to avoid dead-end complex formation at the Golgi membrane. Our data suggest that membrane-interaction modules and cargo-sensing regions have evolved independently in ArfGAP1s versus ArfGAP2/3s.
Schindler
Christina
C
Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Rodriguez
Fernanda
F
Poon
Pak P
PP
Singer
Richard A
RA
Johnston
Gerald C
GC
Spang
Anne
A
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020755:Coat Protein Complex I / Q000378:metabolism; D020756:Coatomer Protein / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D022161:Transport Vesicles / Q000378:metabolism / Q000502:physiology*
D020755:Coat Protein Complex I; D020756:Coatomer Protein; D004268:DNA-Binding Proteins; C089147:GCS1 protein, S cerevisiae; D020690:GTPase-Activating Proteins; C514182:Glo3 protein, S cerevisiae; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins