Structural and mechanistic insights into the association of PKCalpha-C2 domain to PtdIns(4,5)P2.
C2 domains are widely-spread protein signaling motifs that in classical PKCs act as Ca(2+)-binding modules. However, the molecular mechanisms of their targeting process at the plasma membrane remain poorly understood. Here, the crystal structure of PKCalpha-C2 domain in complex with Ca(2+), 1,2-dihexanoyl-sn-glycero-3-[phospho-L-serine] (PtdSer), and 1,2-diayl-sn-glycero-3-[phosphoinositol-4,5-bisphosphate] [PtdIns(4,5)P(2)] shows that PtdSer binds specifically to the calcium-binding region, whereas PtdIns(4,5)P(2) occupies the concave surface of strands beta3 and beta4. Strikingly, the structure reveals a PtdIns(4,5)P(2)-C2 domain-binding mode in which the aromatic residues Tyr-195 and Trp-245 establish direct interactions with the phosphate moieties of the inositol ring. Mutations that abrogate Tyr-195 and Trp-245 recognition of PtdIns(4,5)P(2) severely impaired the ability of PKCalpha to localize to the plasma membrane. Notably, these residues are highly conserved among C2 domains of topology I, and a general mechanism of C2 domain-membrane docking mediated by PtdIns(4,5)P(2) is presented.
Department of Bioquímica y Biología Molecular A, Facultad de Veterinaria, Universidad de Murcia, 30100 Murcia, Spain.
Marta
M
Guerrero-Valero
Cristina
C
Ferrer-Orta
Jordi
J
Querol-Audí
Consuelo
C
Marin-Vicente
Ignacio
I
Fita
Juan C
JC
Gómez-Fernández
Nuria
N
Verdaguer
Senena
S
Corbalán-García
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002412:Cations / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D017124:Conserved Sequence; D005799:Genes, Dominant; D008958:Models, Molecular; D050505:Mutant Proteins / Q000378:metabolism; D016716:PC12 Cells; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D051571:Protein Kinase C-alpha / Q000737:chemistry* / Q000378:metabolism*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D013329:Structure-Activity Relationship
D000596:Amino Acids; D002412:Cations; D050505:Mutant Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D051571:Protein Kinase C-alpha