Multivalent mechanism of membrane insertion by the FYVE domain.
Targeting of a wide variety of proteins to membranes involves specific recognition of phospholipid head groups and insertion into lipid bilayers. For example, proteins that contain FYVE domains are recruited to endosomes through interaction with phosphatidylinositol 3-phosphate (PtdIns(3)P). However, the structural mechanism of membrane docking and insertion by this domain remains unclear. Here, the depth and angle of micelle insertion and the lipid binding properties of the FYVE domain of early endosome antigen 1 are estimated by NMR spectroscopy. Spin label probes incorporated into micelles identify a hydrophobic protuberance that inserts into the micelle core and is surrounded by interfacially active polar residues. A novel proxyl PtdIns(3)P derivative is developed to map the position of the phosphoinositide acyl chains, which are found to align with the membrane insertion element. Dual engagement of the FYVE domain with PtdIns(3)P and dodecylphosphocholine micelles yields a 6-fold enhancement of affinity. The additional interaction of phosphatidylserine with a conserved basic site of the protein further amplifies the micelle binding affinity and dramatically alters the angle of insertion. Thus, the FYVE domain is targeted to endosomes through the synergistic action of stereospecific PtdIns(3)P head group ligation, hydrophobic insertion and electrostatic interactions with acidic phospholipids.
Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA. Kutateladze@UCHSC.edu
Tatiana G
TG
Kutateladze
Daniel G S
DG
Capelluto
Colin G
CG
Ferguson
Matthew L
ML
Cheever
Andrei G
AG
Kutateladze
Glenn D
GD
Prestwich
Michael
M
Overduin
D001665:Binding Sites; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D033921:Vesicular Transport Proteins
D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1