Molecular basis for the substrate specificity of plant guanine nucleotide exchange factors for ROP.
Plant G proteins of the ROP/RAC family regulate cellular processes including cytoskeletal rearrangement in polar growth. Activation of the ROP molecular switch is triggered by guanine nucleotide exchange factors. Plant-specific RopGEFs are exclusively active on ROPs despite their high homology to animal Rho proteins. Based on a sequence comparison of ROPs vs. animal Rho proteins together with structural data on distinct ROPs, we identified unique substrate determinants of RopGEF specificity by mutational analysis: asparagine 68 next to switch II, arginine 76 of a putative phosphorylation motif and the Rho insert are essential for substrate recognition by RopGEFs. These data also provide first evidence for a function of the Rho insert in interactions with GEFs.
Fricke
Inka
I
Max Planck Institute of Molecular Physiology, Structural Biology Department, Dortmund, Germany.
Berken
Antje
A
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D020662:Guanine Nucleotide Exchange Factors; D020559:Monomeric GTP-Binding Proteins