Crystal structure of ARF1*Sec7 complexed with Brefeldin A and its implications for the guanine nucleotide exchange mechanism

Mol Cell. 2003 Dec;12(6):1403-11. doi: 10.1016/s1097-2765(03)00475-1.


ARF GTPases are activated by guanine nucleotide exchange factors (GEFs) of the Sec7 family that promote the exchange of GDP for GTP. Brefeldin A (BFA) is a fungal metabolite that binds to the ARF1*GDP*Sec7 complex and blocks GEF activity at an early stage of the reaction, prior to guanine nucleotide release. The crystal structure of the ARF1*GDP*Sec7*BFA complex shows that BFA binds at the protein-protein interface to inhibit conformational changes in ARF1 required for Sec7 to dislodge the GDP molecule. Based on a comparative analysis of the inhibited complex, nucleotide-free ARF1*Sec7 and ARF1*GDP, we suggest that, in addition to forcing nucleotide release, the ARF1-Sec7 binding energy is used to open a cavity on ARF1 to facilitate the rearrangement of hydrophobic core residues between the GDP and GTP conformations. Thus, the Sec7 domain may act as a dual catalyst, facilitating both nucleotide release and conformational switching on ARF proteins.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ADP-Ribosylation Factor 1 / chemistry*
  • ADP-Ribosylation Factor 1 / metabolism
  • Binding Sites
  • Brefeldin A / chemistry*
  • Brefeldin A / metabolism
  • Crystallography, X-Ray
  • Enzyme Activation
  • Guanine Nucleotide Exchange Factors / chemistry*
  • Guanine Nucleotide Exchange Factors / metabolism
  • Guanosine Diphosphate / chemistry
  • Guanosine Diphosphate / metabolism*
  • Guanosine Triphosphate / metabolism
  • Humans
  • Macromolecular Substances
  • Models, Molecular
  • Protein Structure, Quaternary*
  • Protein Synthesis Inhibitors / chemistry*
  • Protein Synthesis Inhibitors / metabolism


  • Guanine Nucleotide Exchange Factors
  • Macromolecular Substances
  • Protein Synthesis Inhibitors
  • Sec7 guanine nucleotide exchange factors
  • Guanosine Diphosphate
  • Brefeldin A
  • Guanosine Triphosphate
  • ADP-Ribosylation Factor 1

Associated data

  • PDB/1RE0