Crystal structure of the human GGA1 GAT domain.
GGAs are a family of vesicle-coating regulatory proteins that function in intracellular protein transport. A GGA molecule contains four domains, each mediating interaction with other proteins in carrying out intracellular transport. The GAT domain of GGAs has been identified as the structural entity that binds membrane-bound ARF, a molecular switch regulating vesicle-coat assembly. It also directly interacts with rabaptin5, an essential component of endosome fusion. A 2.8 A resolution crystal structure of the human GGA1 GAT domain is reported here. The GAT domain contains four helices and has an elongated shape with the longest dimension exceeding 80 A. Its longest helix is involved in two structural motifs: an N-terminal helix-loop-helix motif and a C-terminal three-helix bundle. The N-terminal motif harbors the most conservative amino acid sequence in the GGA GAT domains. Within this conserved region, a cluster of residues previously implicated in ARF binding forms a hydrophobic surface patch, which is likely to be the ARF-binding site. In addition, a structure-based mutagenesis-biochemical analysis demonstrates that the C-terminal three-helix bundle of this GAT domain is responsible for the rabaptin5 binding. These structural characteristics are consistent with a model supporting multiple functional roles for the GAT domain.
Zhu
Guangyu
G
Crystallography Research Program and Protein Studies Program, Oklahoma Medical Research Foundation, 825 Northeast 13th Street, Oklahoma City, Oklahoma 73104, USA.
Zhai
Peng
P
He
Xiangyuan
X
Terzyan
Simon
S
Zhang
Rongguang
R
Joachimiak
Andrzej
A
Tang
Jordan
J
Zhang
Xuejun C
XC
D020727:ADP-Ribosylation Factors / Q000737:chemistry*; D033942:Adaptor Proteins, Vesicular Transport; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D018076:DNA, Complementary / Q000378:metabolism; D004058:Diffusion; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D033921:Vesicular Transport Proteins / Q000737:chemistry
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D018076:DNA, Complementary; C407306:GGA adaptor proteins; C097227:RABEP1 protein, human; D033921:Vesicular Transport Proteins; D020727:ADP-Ribosylation Factors