A Single Amino Acid Deletion in the Carboxy Terminal of Apolipoprotein A-I Impairs Lipid Binding and Cellular Interaction

Huang, Wei; Sasaki, Jun; Matsunaga, Akira; Han, Ho Jae; Li, Wei; Koga, Takafumi; Kugi, Mari; Andò, Sebastiano; Arakawa, Kikuo

doi:10.1161/01.atv.20.1.210

Cited by 32 publications

(26 citation statements)

References 53 publications

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“…It was reported previously that recombinant proapoA-I Nichinan solubilizes DMPC vesicles more slowly than normal proapoA-I. 5) Our present results suggest that the reduced rate of microsolubilization observed in proapoA-I Nichinan is caused by direct influences of the impaired lipid interaction of the C-terminal region. Hydrophobic acyl chains of phospholipid molecules at the edge of discoidal particles are covered with amphipathic a-helices of apoA-I to stabilize the discoidal HDL structure.…”

Section: )supporting

confidence: 69%

“…4,5) Computational analysis of the amino acid sequence of human apoA-I reveals that residues 44-243, encoded by exon 4, is composed of 11-or 22-amino acid tandem repeats, which can form amphipathic a-helices mostly punctuated by proline residues. 6) Studies of synthetic peptides corresponding to each of 22-residue amphipathic segments of apoA-I have shown that the last repeated helix (residues 220-241) has greatest lipid affinity.…”

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confidence: 99%

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Deletion of Single Amino Acid E235 Affects the Structure and Lipid Interaction of Human Apolipoprotein A-I C-Terminal Peptides

Tanaka

Sugiura

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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Human apolipoprotein (apo) A-I, a 243 amino acid protein, is the major protein component of high-density lipoprotein (HDL). ApoA-I plays an important role in lipoprotein metabolism, reverse cholesterol transport pathway, and protection against the development of atherosclerosis.1) In reverse cholesterol transport pathway, lipid-free or lipid-poor apoA-I molecules remove cholesterol from peripheral cells and transport it in the form of HDL back to the liver for excretion.2) Lipid-free apoA-I is folded into two domains, comprising an N-terminal domain forming a four-helix bundle and a discrete C-terminal domain, which is predominantly involved in lipid-protein interactions. These interactions are critical for HDL generation, including initial lipid binding and cholesterol efflux from plasma membrane.3) ApoA-I Nichinan, a naturally occurring human apoA-I variant with a deletion of E235 located in the C-terminus, is associated with low HDL cholesterolemia probably due to the impaired lipid binding and cellular interactions. 4,5) Computational analysis of the amino acid sequence of human apoA-I reveals that residues 44-243, encoded by exon 4, is composed of 11-or 22-amino acid tandem repeats, which can form amphipathic a-helices mostly punctuated by proline residues. 6) Studies of synthetic peptides corresponding to each of 22-residue amphipathic segments of apoA-I have shown that the last repeated helix (residues 220-241) has greatest lipid affinity. 7,8) In addition, our previous studies using deletion mutants of apoA-I demonstrated that deletion in the last helix leads to significant decreases in lipid-binding affinity compared to intact apoA-I. 9,10) A lack of E235 in apoA-I Nichinan variant is considered to bring about at least two possible structural influences such as 1) a negative charge ablation and 2) disturbance of amino acid distribution on the helix cross-section (i.e., loss of amphipathicity) (Fig. 1). Previously, Panagotopulos et al. have revealed that the E235K mutation in full-length apoA-I does not affect lipid microsolubilization and cellular cholesterol efflux, 11) suggesting the possibility that amphipathic nature of the C-terminal region in apoA-I Nichinan is influenced by the disturbance of amino acid distribution caused by E235 deletion. To examine the influences of E235 deletion on the a-helical structure and lipid interaction of the C-terminal region in apoA-I, we used a series of variant peptides corresponding to residues 220-241 of the apoA-I molecule in addition of DE235: E235A in which E235 was substituted with nonpolar alanine residue to examine the influence of a negative charge ablation, and L230P in which L230 was substituted with proline residue to disrupt the putative a-helical structure. We previously demonstrated that proline insertion instead of leucine residue at position 230 disrupts the C-ter- The C-terminal domain of apolipoprotein (apo) A-I plays an important role in lipid binding. ApoA-I Nichinan, a naturally occurring human apoA-I variant with a deletion of E235 located i...

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Section: )supporting

confidence: 69%

mentioning

confidence: 99%

Deletion of Single Amino Acid E235 Affects the Structure and Lipid Interaction of Human Apolipoprotein A-I C-Terminal Peptides

Tanaka

Sugiura

et al. 2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…The importance of the C terminus (aa 187-243) of apoA-I in both phospholipid binding and cholesterol efflux has been shown previously (41)(42)(43), suggesting these two properties may be related. To determine if either the N-terminal globular domain or helix 1 are involved in cellular cholesterol efflux, we compared the efflux from cholesterol-loaded J774 macrophages to lipid-free His-Wt, His-⌬1-43, His-⌬1-65, and His-⌬210 -243 apoA-I (Table I).…”

Section: The N Terminus Of Apoa-i Is Essential For Hdl Maturationmentioning

confidence: 78%

The N-terminal Globular Domain and the First Class A Amphipathic Helix of Apolipoprotein A-I Are Important for Lecithin:Cholesterol Acyltransferase Activation and the Maturation of High Density Lipoprotein in Vivo

Scott¹,

McManus²,

Franklin³

et al. 2001

Journal of Biological Chemistry

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To investigate the role of the N terminus of apolipoprotein A-I (apoA-I) in the maturation of high density lipoproteins (HDL), two N-terminal mutants with deletions of residues 1-43 and 1-65 (referred to as ⌬1-43 and ⌬1-65 apoA-I) were studied. In vitro, these deletions had little effect on cellular cholesterol efflux from macrophages but LCAT activation was reduced by 50 and 70% for the ⌬1-43 and ⌬1-65 apoA-I mutants, respectively, relative to wild-type (Wt) apoA-I. To further define the role of the N terminus of apoA-I in HDL maturation, we constructed recombinant adenoviruses containing Wt apoA-I and two similar mutants with deletions of residues 7-43 and 7-65 (referred to as ⌬7-43 and ⌬7-65 apoA-I, respectively). Residues 1-6 were not removed in these mutants to allow proper cleavage of the pro-sequence in vivo. Following injection of these adenoviruses into apoA-I-deficient mice, plasma concentrations of both ⌬7-43 and ⌬7-65 apoA-I were reduced 4-fold relative to Wt apoA-I. The N-terminal deletion mutants, in particular ⌬7-65 apoA-I, were associated with greater proportions of pre␤-HDL and accumulated fewer HDL cholesteryl esters relative to Wt apoA-I. Wt and ⌬7-43 apoA-I formed predominantly ␣-migrating and spherical HDL, whereas ⌬7-65 apoA-I formed only pre␤-HDL of discoidal morphology. This demonstrates that deletion of the first class A amphipathic ␣-helix has a profound additive effect in vivo over the deletion of the globular domain alone (amino acids 1-43) indicating its important role in the production of mature ␣-migrating HDL. In summary, the combined in vitro and in vivo studies demonstrate a role for the N terminus of apoA-I in lecithin:cholesterol acyltransferase activation and the requirement of the first class A amphipathic ␣-helix for the maturation of HDL in vivo. High density lipoproteins (HDL)1 transport cholesterol from peripheral tissues to the liver in a process known as reverse cholesterol transport (1). This pathway is accepted as a primary mechanism by which HDL exert their anti-atherogenic effects. Nascent HDL are secreted by hepatocytes, liberated from chylomicrons during triglyceride lipolysis, and are derived from HDL remodeling by hepatic lipase and cholesteryl ester transfer protein. The importance of phospholipid transfer protein (PLTP) in the lipidation of this nascent HDL pool has recently emerged, because PLTP-deficient mice exhibit defective phospholipid transfer from triglyceride-rich lipoproteins to HDL, reduced HDL levels, and increased HDL catabolism (2). Efflux of cholesterol and phospholipids from cells provide nascent HDL with lipid constituents. This step is important for steady-state concentrations of HDL, because efflux is a ratelimiting step in HDL maturation as heterozygous mutations in the ATP binding cassette transporter A1 (ABCA1) can cause familial HDL deficiency (3). The combined actions of PLTP and ABCA1 generate larger discoidal pre␤ 2 and pre␤ 3 -HDL from the nascent HDL pool, which are converted to spherical ␣-migrating HDL by the actions of lecithin:...

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“…The first pathway appears to be mediated by the ATP binding cassette transporter (ABCA1) (37), and the second may involve the scavenger receptor class B, type I (SR-B1) (38). The role of distinct apoA-I domains in cellular cholesterol efflux mediated by either lipid-free or lipidated apoA-I has been addressed by using monoclonal antibodies against epitopes distributed along the entire apoA-I sequence, and by using natural or recombinant apoA-I mutants (39)(40)(41)(42)(43)(44)(45)(46). Taken together, earlier results suggest that sequences in the central (39)(40)(41)(42) and C-terminal (43,44,47) regions of apoA-I may facilitate cholesterol efflux to lipidated apoA-I by interacting with specific lipid domains, or proteins in the cell membrane.…”

Section: Downloaded Frommentioning

confidence: 99%

Apolipoprotein composition and particle size affect HDL degradation by chymase: effect on cellular cholesterol efflux

Lee

Kovanen

Tedeschi

et al. 2003

Journal of Lipid Research

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Mast cell chymase, a chymotrypsin-like neutral protease, can proteolyze HDL 3 . Here we studied the ability of rat and human chymase to proteolyze discoidal pre ␤ -migrating reconstituted HDL particles (rHDLs) containing either apolipoprotein A-I (apoA-I) or apoA-II. Both chymases cleaved apoA-I in rHDL at identical sites, either at the N-terminus (Tyr 18 or Phe 33 ) or at the C-terminus (Phe 225 ), so generating three major truncated polypeptides that remained bound to the rHDL. The cleavage sites were independent of the size of the rHDL particles, but small particles were more susceptible to degradation than bigger ones. Chymase-induced truncation of apoA-I yielded functionally compromised rHDL with reduced ability to promote cellular cholesterol efflux. In sharp contrast to apoA-I, apoA-II was resistant to degradation. However, when apoA-II was present in rHDL that also contained apoA-I, it was degraded by chymase. We conclude that chymase reduces the ability of apoA-I in discoidal rHDL particles to induce cholesterol efflux by cleaving off either its amino-or carboxy-terminal portion. This observation supports the concept that limited extracellular proteolysis of apoA-I is one pathophysiologic mechanism leading to the generation and maintenance of foam cells in atherosclerotic lesions. Chymases are neutral proteases whose specificity is chymotrypsin-like: peptide bonds are cleaved on the carbonyl side of a ) aromatic residues with the order of preference Phe Ͼ Tyr ϾϾ Trp, and b ) the branched aliphatic amino acids Val, Ileu, and Leu (1). These enzymes are produced mainly or exclusively by mast cells, and are also found in mast cells of the human arterial intima, the site of atherogenesis (2). In atherosclerotic lesions, the mast cells are activated and release a fraction of their chymase-containing cytoplasmic secretory granules into their microenvironment, where chymase may act on extracellularly located substrates.Chymase of rat serosal mast cells (rat mast cell protease

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A Single Amino Acid Deletion in the Carboxy Terminal of Apolipoprotein A-I Impairs Lipid Binding and Cellular Interaction

Cited by 32 publications

References 53 publications

Deletion of Single Amino Acid E235 Affects the Structure and Lipid Interaction of Human Apolipoprotein A-I C-Terminal Peptides

Deletion of Single Amino Acid E235 Affects the Structure and Lipid Interaction of Human Apolipoprotein A-I C-Terminal Peptides

The N-terminal Globular Domain and the First Class A Amphipathic Helix of Apolipoprotein A-I Are Important for Lecithin:Cholesterol Acyltransferase Activation and the Maturation of High Density Lipoprotein in Vivo

Apolipoprotein composition and particle size affect HDL degradation by chymase: effect on cellular cholesterol efflux

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