Structural basis for Rab GTPase recognition and endosome tethering by the C2H2 zinc finger of Early Endosomal Autoantigen 1 (EEA1).
Regulation of endosomal trafficking by Rab GTPases depends on selective interactions with multivalent effectors, including EEA1 and Rabenosyn-5, which facilitate endosome tethering, sorting, and fusion. Both EEA1 and Rabenosyn-5 contain a distinctive N-terminal C(2)H(2) zinc finger that binds Rab5. How these C(2)H(2) zinc fingers recognize Rab GTPases remains unknown. Here, we report the crystal structure of Rab5A in complex with the EEA1 C(2)H(2) zinc finger. The binding interface involves all elements of the zinc finger as well as a short N-terminal extension but is restricted to the switch and interswitch regions of Rab5. High selectivity for Rab5 and, to a lesser extent Rab22, is observed in quantitative profiles of binding to Rab family GTPases. Although critical determinants are identified in both switch regions, Rab4-to-Rab5 conversion-of-specificity mutants reveal an essential requirement for additional substitutions in the proximal protein core that are predicted to indirectly influence recognition through affects on the structure and conformational stability of the switch regions.
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Ashwini
A
Mishra
Sudharshan
S
Eathiraj
Silvia
S
Corvera
David G
DG
Lambright
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001324:Autoantigens / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D011992:Endosomes / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D033921:Vesicular Transport Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D016335:Zinc Fingers; D020691:rab GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D020695:rab4 GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D001324:Autoantigens; D046912:Multiprotein Complexes; C416362:RBSN protein, human; D011994:Recombinant Proteins; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins