ATP hydrolysis-dependent conformational changes in the extracellular domain of ABCA1 are associated with apoA-I binding

Abstract

ATP-binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high-density lipoprotein (HDL) metabolism. Although it is predicted that apolipoprotein A-I (apoA-I) directly binds to ABCA1, the physiological importance of this interaction is still controversial and the conformation required for apoA-I binding is unclear. In this study, the role of the two nucleotide-binding domains (NBD) of ABCA1 in apoA-I binding was determined by inserting a TEV protease recognition sequence in the linker region of ABCA1. Analyses of ATP binding and occlusion to wild-type ABCA1 and various NBD mutants revealed that ATP binds equally to both NBDs and is hydrolyzed at both NBDs. The interaction with apoA-I and the apoA-I-dependent cholesterol efflux required not only ATP binding but also hydrolysis in both NBDs. NBD mutations and cellular ATP depletion decreased the accessibility of antibodies to a hemagglutinin (HA) epitope that was inserted at position 443 in the extracellular domain (ECD), suggesting that the conformation of ECDs is altered by ATP hydrolysis at both NBDs. These results suggest that ATP hydrolysis at both NBDs induces conformational changes in the ECDs, which are associated with apoA-I binding and cholesterol efflux. ATP-binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high-density lipoprotein (HDL) metabolism. Although it is predicted that apolipoprotein A-I (apoA-I) directly binds to ABCA1, the physiological importance of this interaction is still controversial and the conformation required for apoA-I binding is unclear. In this study, the role of the two nucleotide-binding domains (NBD) of ABCA1 in apoA-I binding was determined by inserting a TEV protease recognition sequence in the linker region of ABCA1. Analyses of ATP binding and occlusion to wild-type ABCA1 and various NBD mutants revealed that ATP binds equally to both NBDs and is hydrolyzed at both NBDs. The interaction with apoA-I and the apoA-I-dependent cholesterol efflux required not only ATP binding but also hydrolysis in both NBDs. NBD mutations and cellular ATP depletion decreased the accessibility of antibodies to a hemagglutinin (HA) epitope that was inserted at position 443 in the extracellular domain (ECD), suggesting that the conformation of ECDs is altered by ATP hydrolysis at both NBDs. These results suggest that ATP hydrolysis at both NBDs induces conformational changes in the ECDs, which are associated with apoA-I binding and cholesterol efflux. Cholesterol is an essential component of cellular membranes, but excess cholesterol accumulation is harmful to cells. Therefore, cellular cholesterol levels are extensively regulated by various mechanisms (1.Goldstein J.L. DeBose-Boyd R.A. Brown M.S. Protein sensors for membrane sterols.Cell. 2006; 124: 35-46Abstract Full Text Full Text PDF PubMed Scopus (1232) Google Scholar, 2.Nagao K. Tomioka M. Ueda K. Function and regulation of ABCA1--membrane meso-domain organization and re-organization.FEBS J. 2011; 278: 3190-3203Crossref PubMed Scopus (46) Google Scholar). Mutations in the ATP binding cassette protein A1 (ABCA1) gene lead to Tangier disease, which is characterized by an accumulation of excess cellular cholesterol and low plasma high-density lipoprotein (HDL) (3.Bodzioch M. Orso E. Klucken J. Langmann T. Bottcher A. Diederich W. Drobnik W. Barlage S. Buchler C. Porsch-Ozcurumez M. et al.The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease.Nat. Genet. 1999; 22: 347-351Crossref PubMed Scopus (1345) Google Scholar, 4.Brooks-Wilson A. Marcil M. Clee S. Zhang L. Roomp K. van Dam M. Yu L. Brewer C. Collins J. Molhuizen H. et al.Mutations in ABC1 in Tangier disease and familial high-density lipoprotein deficiency.Nat. Genet. 1999; 22: 336-345Crossref PubMed Scopus (1505) Google Scholar, 5.Rust S. Rosier M. Funke H. Real J. Amoura Z. Piette J. Deleuze J. Brewer H. Duverger N. Denefle P. et al.Tangier disease is caused by mutations in the gene encoding ATP-binding cassette transporter 1.Nat. Genet. 1999; 22: 352-355Crossref PubMed Scopus (1266) Google Scholar). The link between the ABCA1 gene and Tangier disease indicates that ABCA1 plays a pivotal role in cholesterol homeostasis by generating HDL, the only pathway that eliminates excess cholesterol from nonhepatic cells. ABCA1 mediates apolipoprotein A-I (apoA-I) binding to the cell surface and the loading of cellular cholesterol and phospholipids onto apoA-I to form pre-βHDL (6.Oram J.F. Lawn R.M. Garvin M.R. Wade D.P. ABCA1 is the cAMP-inducible apolipoprotein receptor that mediates cholesterol secretion from macrophages.J. Biol. Chem. 2000; 275: 34508-34511Abstract Full Text Full Text PDF PubMed Scopus (474) Google Scholar, 7.Tanaka A.R. Abe-Dohmae S. Ohnishi T. Aoki R. Morinaga G. Okuhira K.I. Ikeda Y. Kano F. Matsuo M. Kioka N. et al.Effects of mutations of ABCA1 in the first extracellular domain on subcellular trafficking and ATP binding/hydrolysis.J. Biol. Chem. 2003; 278: 8815-8819Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar, 8.Wang N. Silver D. Costet P. Tall A. Specific binding of ApoA-I, enhanced cholesterol efflux, and altered plasma membrane morphology in cells expressing ABC1.J. Biol. Chem. 2000; 275: 33053-33058Abstract Full Text Full Text PDF PubMed Scopus (507) Google Scholar, 9.Yokoyama S. Release of cellular cholesterol: molecular mechanism for cholesterol homeostasis in cells and in the body.Biochim. Biophys. Acta. 2000; 1529: 231-244Crossref PubMed Scopus (117) Google Scholar). Recently, it was reported that the capacity of macrophages to mediate cholesterol efflux to HDL is strongly and inversely associated with both carotid intima-media thickness and the likelihood of angiographic coronary artery disease, independent of HDL cholesterol levels (10.Khera A.V. Cuchel M. de la Llera-Moya M. Rodrigues A. Burke M.F. Jafri K. French B.C. Phillips J.A. Mucksavage M.L. Wilensky R.L. et al.Cholesterol efflux capacity, high-density lipoprotein function, and atherosclerosis.N. Engl. J. Med. 2011; 364: 127-135Crossref PubMed Scopus (1541) Google Scholar). However, despite the physiological importance of this pathway, the mechanism by which ABCA1 mediates cholesterol efflux remains unclear (11.Nagao K. Kimura Y. Mastuo M. Ueda K. Lipid outward translocation by ABC proteins.FEBS Lett. 2010; 584: 2717-2723Crossref PubMed Scopus (46) Google Scholar). ABCA1 has two intracellular nucleotide-binding domains (NBD) (Fig. 1), whose amino acid sequences are highly conserved among ABC proteins. Chambenoit et al. reported that substituting the Walker A lysine residue in either NBD with methionine (K939M or K1952M) abolishes the ability of apoA-I to bind to ABCA1-expressing cells and inhibits cholesterol secretion to apoA-I (12.Chambenoit O. Hamon Y. Marguet D. Rigneault H. Rosseneu M. Chimini G. Specific docking of apolipoprotein A-I at the cell surface requires a functional ABCA1 transporter.J. Biol. Chem. 2001; 276: 9955-9960Abstract Full Text Full Text PDF PubMed Scopus (177) Google Scholar). Because these lysine residues are essential for ATPase activity (13.Takahashi K. Kimura Y. Kioka N. Matsuo M. Ueda K. Purification and ATPase activity of human ABCA1.J. Biol. Chem. 2006; 281: 10760-10768Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar) and thus for the transport activity of ABC proteins, it was predicted that ABCA1 induces a local and transient modification in the spatial arrangement of lipid species on the outer membrane leaflet and that this membrane modification generates apoA-I-docking sites on the cell surface (8.Wang N. Silver D. Costet P. Tall A. Specific binding of ApoA-I, enhanced cholesterol efflux, and altered plasma membrane morphology in cells expressing ABC1.J. Biol. Chem. 2000; 275: 33053-33058Abstract Full Text Full Text PDF PubMed Scopus (507) Google Scholar, 14.Hamon Y. Broccardo C. Chambenoit O. Luciani M. Toti F. Chaslin S. Freyssinet J. Devaux P. J. Marguet D. et of cells and of Biol. 2000; PubMed Scopus Google Scholar, C. M. D. P. H. S. Phillips of ATP-binding cassette transporter cellular lipid efflux to apolipoprotein A-I and of lipoprotein Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, G. J.F. binding to membrane domains of excess cellular 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). ABCA1 has two extracellular domains 1 and (Fig. are between the two ECDs of ABCA1, and these are for apoA-I binding and HDL M. Kimura Y. Kioka N. Ueda K. of two is for cholesterol efflux by ABCA1.J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). to that apoA-I directly binds to ABCA1 (6.Oram J.F. Lawn R.M. Garvin M.R. Wade D.P. ABCA1 is the cAMP-inducible apolipoprotein receptor that mediates cholesterol secretion from macrophages.J. Biol. Chem. 2000; 275: 34508-34511Abstract Full Text Full Text PDF PubMed Scopus (474) Google Scholar, 8.Wang N. Silver D. Costet P. Tall A. Specific binding of ApoA-I, enhanced cholesterol efflux, and altered plasma membrane morphology in cells expressing ABC1.J. Biol. Chem. 2000; 275: 33053-33058Abstract Full Text Full Text PDF PubMed Scopus (507) Google Scholar, M.L. A. ABCA1 and form molecular required for cholesterol Lipid Full Text Full Text PDF PubMed Scopus Google Scholar, A. T. M.L. and lipid efflux of apoA-I mutants suggest between apoA-I and PubMed Scopus Google Scholar, C. S. Phillips cell surface binding sites for Biol. PubMed Scopus Google Scholar, K. Kimura Y. Ueda K. residues of ABCA1 are required for the interaction with Biophys. Scholar). Because a apoA-I with ABCA1 A. T. M.L. and lipid efflux of apoA-I mutants suggest between apoA-I and PubMed Scopus Google Scholar) and the bind or to apoA-I N. Silver C. Tall A.R. ATP-binding cassette transporter A1 (ABCA1) a cholesterol efflux Biol. Chem. 2001; 276: Full Text Full Text PDF PubMed Scopus Google it is that apoA-I with of the ECDs that are by the two and in an However, the importance of a interaction in HDL is still and it is unclear conformation of ABCA1 mediates apoA-I binding and this conformation is In this study, ATP binding and hydrolysis for NBD of ABCA1 and the of the NBDs to apoA-I binding and HDL the of these determined that ATP conformational changes in the ECDs of ABCA1 are associated with apoA-I binding and cholesterol efflux by ABCA1. The was the amino of ABCA1 Y. Ohnishi T. S. A. K. M. T. S. T. Matsuo M. et of ABCA1.J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The was of ABCA1 Y. Ohnishi T. S. A. K. M. T. S. T. Matsuo M. et of ABCA1.J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). was the of ABCA1 (13.Takahashi K. Kimura Y. Kioka N. Matsuo M. Ueda K. Purification and ATPase activity of human ABCA1.J. Biol. Chem. 2006; 281: 10760-10768Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). and antibodies from was from protease was from apoA-I and apoA-I reported Y. M. Kioka N. K. Ueda K. pathway of to HDL PubMed Scopus Google Scholar). The from and cells in a at in with The for wild-type ABCA1, and that with at the A.R. Abe-Dohmae S. Ohnishi T. Aoki R. Morinaga G. Okuhira K.I. Ikeda Y. Kano F. Matsuo M. Kioka N. et al.Effects of mutations of ABCA1 in the first extracellular domain on subcellular trafficking and ATP binding/hydrolysis.J. Biol. Chem. 2003; 278: 8815-8819Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar, K. Kimura Y. Kioka N. Matsuo M. Ueda K. Purification and ATPase activity of human ABCA1.J. Biol. Chem. 2006; 281: 10760-10768Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). The hemagglutinin (HA) epitope sequence was between and reported A.R. Ikeda Y. Abe-Dohmae S. R. K. A. S. T. Aoki R. Kioka N. et ABCA1 a extracellular domain to an epitope of Biophys. 2001; PubMed Scopus Google Scholar). an or a at a was and of a an and or a and the The TEV protease recognition sequence was between and of by and The mutated was by cells with and to the the cells with and with and in A 1 and the protease and The on and with the in at a of cells in the cells with and in and the cholesterol in the was determined a or a S. S. Y. H. S. of HDL by in a cell 2000; PubMed Scopus Google Scholar, M. for the of Biophys. 1999; PubMed Scopus Google Scholar). on for The cells with and and with in for on in the The cells with and to and in and protease was to the cell to the proteins, which on a and on with and apoA-I for at The cells with at for and with a on with or in for at The cells and with at for with the cells with an and with a ATP was by with and in for from cells that or on with and in a of for and for on ATP was by and 1 and the was The in and and ABCA1 was with The on and by The by with the from cells that or The membrane with or and in a of at The activity of was that of The by of and 1 ATP from the membrane and the was The in of 1 and for on The on and by The by the or an ABCA1 was with TEV protease at for to the are the The of between was the A was the interaction between apoA-I and ABCA1-expressing the of cellular ATP apoA-I was to the apoA-I to ABCA1-expressing cells but not to the reported Y. M. Kioka N. K. Ueda K. pathway of to HDL PubMed Scopus Google Scholar, K. Y. K. Kimura Y. Ueda K. lipid efflux by of on lipid translocation and apolipoprotein A-I Lipid Full Text Full Text PDF PubMed Scopus Google Scholar) (Fig. the intracellular ATP levels by the cells with and for apoA-I binding was ABCA1 on the plasma membrane was not (Fig. the cells in for ATP depletion apoA-I binding to levels to ATP depletion (Fig. These results suggest that apoA-I binding is and The apoA-I on the cell surface both the binding to ABCA1 and the of apoA-I to the cell The of the two NBDs of ABCA1 to apoA-I binding and cholesterol efflux by ABCA1 was ABCA1 apoA-I-dependent cholesterol efflux. However, cholesterol efflux was in cells expressing a in which the Walker A in both NBDs are with or the Walker A lysine mutants or in which the Walker A lysine in or is with methionine (Fig. these mutations not the levels (Fig. and at a of the mutants on the plasma membrane (Fig. binding was also either Walker A lysine was with methionine (Fig. These results suggest that the two NBDs are required for apoA-I binding and apoA-I-dependent cholesterol efflux by ABCA1. has reported that the two NBDs in ABC not in the ATP hydrolysis and transport M. of the functional of the binding domains of protein Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar, L. The first binding domain of is a of the is a of Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, M. K. Kioka N. T. Ueda K. binding and for ATP and among receptor and Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar, J. S. interaction between the two of the ATP binding cassette protein for a in the first binding Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar). the two NBDs of ABCA1 with ATP and are in the of ABCA1, the of Walker A lysine mutations in NBD on ATP binding (Fig. from cells expressing the wild-type or ABCA1 with for on and ABCA1 was from wild-type ABCA1-expressing cells but not from the cells. was by excess of that the was A Walker A lysine not ATP binding to ABCA1, suggesting that the Walker A lysine residues are not essential for ATP binding to ABCA1. binding was ABCA1 was strongly reported A.R. Abe-Dohmae S. Ohnishi T. Aoki R. Morinaga G. Okuhira K.I. Ikeda Y. Kano F. Matsuo M. Kioka N. et al.Effects of mutations of ABCA1 in the first extracellular domain on subcellular trafficking and ATP binding/hydrolysis.J. Biol. Chem. 2003; 278: 8815-8819Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar). These results that the was in the NBD of ABCA1 at expressing wild-type ABCA1 with for at and on the (Fig. The of not the of ABCA1 reported A.R. Abe-Dohmae S. Ohnishi T. Aoki R. Morinaga G. Okuhira K.I. Ikeda Y. Kano F. Matsuo M. Kioka N. et al.Effects of mutations of ABCA1 in the first extracellular domain on subcellular trafficking and ATP binding/hydrolysis.J. Biol. Chem. 2003; 278: 8815-8819Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar). The decreased the by and not the the the decreased the by the of enhanced the of suggesting that the at ATP was with was for the was with the wild-type or of the ABCA1 mutants (Fig. ABCA1 was strongly was a These results suggest that the in the NBD of wild-type ABCA1, and is not ATP but that both NBDs ATP and that the of the two NBDs of ABCA1 are the interaction of NBD with in first a with to the two NBDs. However, of ABCA1 at two is between and and the is in the linker region between the two of ABCA1 (13.Takahashi K. Kimura Y. Kioka N. Matsuo M. Ueda K. Purification and ATPase activity of human ABCA1.J. Biol. Chem. 2006; 281: 10760-10768Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). it was to ATP binding to Therefore, a to the two NBDs of ABCA1. that the in the linker region was and ABCA1 at this a TEV protease recognition sequence TEV protease between and was between and (Fig. 1 and of the TEV sequence not the cellular of ABCA1 or the ability of ABCA1 to bind apoA-I and mediate apoA-I-dependent cholesterol efflux (Fig. TEV of a and (Fig. which not an inserted TEV was not by the TEV protease (Fig. that the by TEV protease is and that the two NBDs of ABCA1 by TEV protease ATP binding to NBD was (Fig. ATP equally to both NBDs in ABCA1 reported J. S. interaction between the two of the ATP binding cassette protein for a in the first binding Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar). Walker A lysine mutations in both NBDs not ATP binding to ATP binding to in the for this interaction is binding to NBD was The wild-type and of ABCA1 the TEV sequence a occlusion (Fig. that was to that of the ABCA1 (Fig. that of the TEV sequence not the nucleotide-binding of ABCA1. wild-type ABCA1 was with and by the TEV protease occlusion was in and occlusion was in (Fig. However, was was The the of with with the in the of the and protease it to the mutants (Fig. was for the with In at either NBD in the These results suggest that ATP is hydrolyzed at both NBDs of ABCA1 and that is in both NBDs ATP a Walker A lysine has a on occlusion in in Because apoA-I binding is and that the are in the ECDs of ABCA1 in an (Fig. ATP binding hydrolysis conformational changes in the ECDs, an was sites in the ECDs of ABCA1, and the accessibility of an was cellular ATP the of ABCA1 was the that are to on the surface of ABCA1 for The was inserted sites in and in (Fig. mutants and at the plasma membrane and apoA-I binding to wild-type (Fig. However, mutants and only to the plasma membrane and not mediate apoA-I to the accessibility of the cells expressing the mutants with the at for in cells and with an (Fig. mutants and on the plasma membrane with the the not with the it was at the plasma membrane and apoA-I is that the epitope is mutants and which only to the plasma not with the conformational changes in ABCA1, the accessibility of the to the in mutants was cellular ATP depletion (Fig. The of the of the was decreased ATP of the mutants and was not These results suggest that the accessibility of the to the at 443 is altered by ATP the of the two NBDs to the conformational changes in the ECDs, Walker A lysine mutations the and the mutants for the Walker A lysine residue in either NBD of decreased the of (Fig. and apoA-I binding (Fig. cell surface or the with the in was not (Fig. However, the in not (Fig. the was inserted position both Walker A lysine with the also decreased (Fig. suggesting that the in not the in of the epitope the Because the and mutants the apoA-I binding (Fig. and apoA-I-dependent cholesterol efflux (Fig. the of or the position 443 not the of ABCA1. Therefore, the conformational changes of the and mutants the are predicted to the of the wild-type ABCA1. these results suggest that ATP hydrolysis at both NBDs induces conformational changes in the ECDs that accessibility to the region 443 and that these conformational changes are associated with apoA-I of an or a inserted at position 443 on the and subcellular of ABCA1. with and apoA-I for Cholesterol efflux was with ABCA1 for in with or with and cell surface with from of cell The surface and cell and with an a The of cell surface ABCA1 was with ABCA1. and with the The of or was with that of The first in HDL is the binding of apoA-I to the plasma membrane of cells. requires ABCA1 that is on the plasma ABCA1 is by the receptor that is by which are of excess Because ABCA1 is a of the ABC protein of which mediate efflux and lipid transport in an it has that membrane translocation ABCA1 generates membrane domains that are by apoA-I (8.Wang N. Silver D. Costet P. Tall A. Specific binding of ApoA-I, enhanced cholesterol efflux, and altered plasma membrane morphology in cells expressing ABC1.J. Biol. Chem. 2000; 275: 33053-33058Abstract Full Text Full Text PDF PubMed Scopus (507) Google Scholar, 14.Hamon Y. Broccardo C. Chambenoit O. Luciani M. Toti F. Chaslin S. Freyssinet J. Devaux P. J. Marguet D. et of cells and of Biol. 2000; PubMed Scopus Google Scholar, C. M. D. P. H. S. Phillips of ATP-binding cassette transporter cellular lipid efflux to apolipoprotein A-I and of lipoprotein Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, G. J.F. binding to membrane domains of excess cellular 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). In this study, the of the two NBDs to ABCA1 the Walker A lysine in NBD was with amino acid in either NBD apoA-I binding and apoA-I-dependent cholesterol efflux by ABCA1, but it not ATP binding to the NBDs. The amino acid of in the Walker which is in ATP hydrolysis but not in ATP binding G. of residues in the two binding domains of generates a conformation that binds ATP and Biol. Chem. Full Text Full Text PDF PubMed Scopus Google in either NBD apoA-I binding and apoA-I-dependent cholesterol efflux by ABCA1 These results suggest that the two NBDs are required for ABCA1 function, that ATP binding to NBDs is not and that ATP hydrolysis is required for apoA-I binding and apoA-I-dependent cholesterol efflux by ABCA1. in the interaction between NBD and a and in the linker region between the two of ABCA1 and inserted a TEV protease recognition sequence that ABCA1. TEV of ABCA1 with and with the of mutations on the of ABCA1, revealed the of NBD of ATP binds equally to both ATP is hydrolyzed at both occlusion in in the of a occlusion in hydrolysis in the of and Walker A lysine mutations in either NBD occlusion in both NBDs. The of the two NBDs in the ATP hydrolysis reported for ABC proteins. The two NBDs of are The of Lett. PubMed Scopus Google has also reported Y. K. Y. K. Matsuo M. T. T. Ueda K. between the two nucleotide-binding of Biophys. Acta. PubMed Scopus Google Scholar). ATP hydrolysis The of Lett. PubMed Scopus Google and is equally in both NBDs in the of S. nucleotide-binding sites are Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). However, in ABC proteins, the two NBDs are to and the In the of ATP is hydrolyzed only at plays a role M. of the functional of the binding domains of protein Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar). for L. The first binding domain of is a of the is a of Biol. Chem. Full Text Full Text PDF PubMed Scopus Google M. K. Kioka N. T. Ueda K. binding and for ATP and among receptor and Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google and J. S. interaction between the two of the ATP binding cassette protein for a in the first binding Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar). that are with P. R. M. J. A of the 2000; PubMed Scopus Google Scholar, of the protein and 2001; PubMed Scopus Google Scholar). and are not but a and a K. Matsuo M. K. Kioka N. T. of the and mechanism of and Biophys. Acta. 1999; PubMed Scopus Google Scholar). In only binds and a plays a role in J. S. interaction between the two of the ATP binding cassette protein for a in the first binding Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar). Although and ABCA1 and are predicted to the of transport are to H. R. J. ATP hydrolysis by and the ATP-binding cassette transporter for Biol. Chem. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). Because the two NBDs of ABCA1 ATP and for the of ABCA1, the ATP hydrolysis for ABCA1 that of that of the ABC proteins. Because apoA-I binding is ATP that ATP hydrolysis conformational changes in the ECDs to this is the an was in the ECDs, and the accessibility of an was and cellular ATP that of the was decreased by ATP suggesting that the region 443 in an the Walker A lysine residue in either NBD of decreased the of (Fig. and apoA-I the in not (Fig. the was inserted position both Walker A lysine with the also decreased (Fig. suggesting that the in not the in of the epitope the these results suggest that ATP hydrolysis at both NBDs induces conformational changes in the and accessibility to the region has that ATP binding conformational changes in ABC The ATP for ABC Biol. PubMed Scopus Google Scholar). ATP binding the conformation from an to an ATP hydrolysis is to the protein to the Because changes in apoA-I binding and accessibility to ATP it is that the are by the of ATP hydrolysis and that are not to ATP The extracellular domain of ABCA1 is with and A.R. Ikeda Y. Abe-Dohmae S. R. K. A. S. T. Aoki R. Kioka N. et ABCA1 a extracellular domain to an epitope of Biophys. 2001; PubMed Scopus Google which are by two M. Kimura Y. Kioka N. Ueda K. of two is for cholesterol efflux by ABCA1.J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). that lipid accumulation the extracellular domain ATP lipid transport conformational changes that on the surface of the extracellular domain and that apoA-I to the is directly with by ABCA1 K. ABC the human and 2011; PubMed Scopus Google Scholar). Because accessibility was for only of sites in the ECDs, apoA-I bind to the ECDs, on apoA-I binding or the was with the or apoA-I These results suggest that the apoA-I binding is not to position the of position 443 to the surface of the is by the of the apoA-I binding Recently, reported that lysine residues in the ECDs of ABCA1 to the interaction with apoA-I and that the interaction between ABCA1 and apoA-I is predicted to the first in HDL K. Kimura Y. Ueda K. residues of ABCA1 are required for the interaction with Biophys. Scholar). ATP hydrolysis conformational changes that a lysine on the surface of the extracellular domain of the mechanism of HDL by ABCA1. with extracellular domain protein hemagglutinin human nucleotide-binding domain