It takes two to tango: PROPPINs use two phosphoinositide-binding sites.
PROPPINs are a family of PtdIns3P and PtdIns(3,5)P 2-binding proteins. The crystal structure now unravels the presence of two distinct phosphoinositide-binding sites at the circumference of the seven bladed β-propeller. Mutagenesis analysis of the binding sites shows that both are required for normal membrane association and autophagic activities. We identified a set of evolutionarily conserved basic and polar residues within both binding pockets, which are crucial for phosphoinositide binding. We expect that membrane association of PROPPINs is further stabilized by membrane insertions and interactions with other proteins.
Department of Biochemistry II, Georg-August University, Göttingen, Germany. mthumm@uni-goettingen.de
Michael
M
Thumm
Ricarda A
RA
Busse
Andreea
A
Scacioc
Milena
M
Stephan
Andreas
A
Janshoff
Karin
K
Kühnel
Roswitha
R
Krick
D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism*; D007716:Kluyveromyces / Q000378:metabolism; D008958:Models, Molecular; D016296:Mutagenesis; D018129:Phosphatidylinositol Phosphates / Q000235:genetics / Q000378:metabolism; D010716:Phosphatidylinositols / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D005656:Fungal Proteins; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D029701:Saccharomyces cerevisiae Proteins; C106336:phosphatidylinositol 3,5-diphosphate; C055525:phosphatidylinositol 3-phosphate