A new functional domain of guanine nucleotide dissociation inhibitor (alpha-GDI) involved in Rab recycling.
Guanine nucleotide dissociation inhibitor (GDI) is a 55-kDa protein that functions in vesicular membrane transport to recycle Rab GTPases. We have now determined the crystal structure of bovine alpha-GDI at ultra-high resolution (1.04 A). Refinement at this resolution highlighted a region with high mobility of its main-chain residues. This corresponded to a surface loop in the primarily alpha-helical domain II at the base of alpha-GDI containing the previously uncharacterized sequence-conserved region (SCR) 3A. Site-directed mutagenesis showed that this mobile loop plays a crucial role in binding of GDI to membranes and extraction of membrane-bound Rab. This domain, referred to as the mobile effector loop, in combination with Rab-binding residues found in the multi-sheet domain I at the apex of alpha-GDI may provide flexibility for recycling of diverse Rab GTPases. We propose that conserved residues in domains I and II synergize to form the functional face of GDI, and that domain II mediates a critical step in Rab recycling during vesicle fusion.
Luan
P
P
Department of Molecular Biology, Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA.
Heine
A
A
Zeng
K
K
Moyer
B
B
Greasely
S E
SE
Kuhn
P
P
Balch
W E
WE
Wilson
I A
IA
D020816:Amino Acid Motifs; D000818:Animals; D002417:Cattle; D018360:Crystallography, X-Ray; D003600:Cytosol / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000737:chemistry* / Q000502:physiology; D007425:Intracellular Membranes / Q000378:metabolism; D008958:Models, Molecular; D009038:Motion; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics; D013329:Structure-Activity Relationship; D022161:Transport Vesicles / Q000378:metabolism; D020761:rab1 GTP-Binding Proteins / Q000378:metabolism*
D005656:Fungal Proteins; C086796:GDP dissociation inhibitor 1; D020730:Guanine Nucleotide Dissociation Inhibitors; D011993:Recombinant Fusion Proteins; D020761:rab1 GTP-Binding Proteins