Conformational dynamics of the major yeast phosphatidylinositol transfer protein sec14p: insight into the mechanisms of phospholipid exchange and diseases of sec14p-like protein deficiencies.
Molecular dynamics simulations coupled with functional analyses of the major yeast phosphatidylinositol/phosphatidylcholine transfer protein Sec14p identify structural elements involved in regulating the ability of Sec14p to execute phospholipid exchange. The molecular dynamics simulations suggest large rigid body motions within the Sec14p molecule accompany closing and opening of an A(10)/T(4)/A(11) helical gate, and that "state-of-closure" of this helical gate determines access to the Sec14p phospholipid binding cavity. The data also project that conformational dynamics of the helical gate are controlled by a hinge unit (residues F(212), Y(213), K(239), I(240), and I(242)) that links to the N- and C-terminal ends of the helical gate, and by a novel gating module (composed of the B(1)LB(2) and A(12)LT(5) substructures) through which conformational information is transduced to the hinge. The (114)TDKDGR(119) motif of B(1)LB(2) plays an important role in that transduction process. These simulations offer new mechanistic possibilities for an important half-reaction of the Sec14p phospholipid exchange cycle that occurs on membrane surfaces after Sec14p has ejected bound ligand, and is reloading with another phospholipid molecule. These conformational transitions further suggest structural rationales for known disease missense mutations that functionally compromise mammalian members of the Sec14-protein superfamily.
Ryan
Margaret M
MM
Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Research Center, University of North Carolina at Chapel Hill, NC 27599-7090, USA.
Temple
Brenda R S
BR
Phillips
Scott E
SE
Bankaitis
Vytas A
VA
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D049294:Phospholipid Transfer Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
D002352:Carrier Proteins; D049294:Phospholipid Transfer Proteins; D011994:Recombinant Proteins; C483438:SEC14 protein, S cerevisiae; C100642:SEC14L1 protein, human; D029701:Saccharomyces cerevisiae Proteins