Structure and phospholipid transfer activity of human PLTP: Analysis by molecular modelling and site-directed mutagenesis

Huuskonen, Jarkko; Wohlfahrt, Gerd; Jauhiainen, Matti; Ehnholm, Christian; Teleman, Olle; Olkkonen, Vesa M.

doi:10.1016/s0021-9150(99)80325-6

Cited by 29 publications

(45 citation statements)

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“…According to this analysis, mAb 66 reacts with the region of amino acids 225-235 of PLTP, ASTSNLDMDFR. The molecular model of PLTP (31) predicts that this peptide region, especially the sequence STSN, is in a turn on the surface of PLTP and well exposed for antigenic reactions.…”

Section: Methodsmentioning

confidence: 99%

The Mechanism of the Remodeling of High Density Lipoproteins by Phospholipid Transfer Protein

Settasatian¹,

Duong²,

Curtiss³

et al. 2001

Journal of Biological Chemistry

115

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Phospholipid transfer protein (PLTP) remodels high density lipoproteins (HDL) into large and small particles. It also mediates the dissociation of lipid-poor or lipid-free apolipoprotein A-I (apoA-I) from HDL. Remodeling is enhanced markedly in triglyceride (TG)-enriched HDL (Rye, K.-A., Jauhiainen, M., Barter, P. J., and Ehnholm. C. (1998) J. Lipid. Res. 39, 613-622). This study defines the mechanism of the remodeling of HDL by PLTP and determines why it is enhanced in TG-enriched HDL. Homogeneous populations of spherical reconstituted HDL (rHDL) containing apoA-I and either cholesteryl esters only (CE-rHDL; diameter 9.3 nm) or CE and TG in their core (TG-rHDL; diameter 9.5 nm) were used. After 24 h of incubation with PLTP, all of the TG-rHDL, but only a proportion of the CE-rHDL, were converted into large (11.3-nm diameter) and small (7.7-nm diameter) particles. Only small particles were formed during the first 6 h of incubation of CE-rHDL with PLTP. The large particles and dissociated apoA-I were apparent after 12 h. In the case of TG-rHDL, small particles appeared after 1 h of incubation, while dissociated apoA-I and large particles were apparent at 3 h. The composition of the large particles indicated that they were derived from a fusion product. Spectroscopic studies indicated that the apoA-I in TG-rHDL was less stable than the apoA-I in CE-rHDL. In conclusion, these results show that (i) PLTP mediates rHDL fusion, (ii) the fusion product rearranges by two independent processes into small and large particles, and (iii) the more rapid remodeling of TG-rHDL by PLTP may be due to the destabilization of apoA-I. Phospholipid transfer protein (PLTP)1 transfers phospholipids (PL) between high density lipoproteins (HDL) and very low density lipoproteins as well as between different particles within the HDL fraction (1, 2). It also remodels HDL into large and small particles in a process that is accompanied by the dissociation of lipid-poor or lipid-free apolipoprotein A-I (apoA-I) (3-8). Remodeling is enhanced markedly in HDL that contain triglyceride (TG) in their core (9). Evidence of the importance of PLTP in HDL metabolism comes from studies of mice transgenic for human PLTP. These animals have increased levels of pre-␤ 1 -migrating HDL, the initial acceptors of cellular cholesterol in the first step of the reverse cholesterol pathway, and are also resistant to intracellular cholesterol accumulation (10 -12). Studies of PLTP knockout mice have shown that PLTP is essential for maintaining normal HDL levels in plasma (13). Moreover, it has been reported recently that PLTP-mediated transfers of phospholipids between HDL and other lipoprotein classes are not interchangeable with the phospholipid transfers that are mediated by cholesteryl ester transfer protein (CETP) (14).The mechanism of the remodeling of HDL by PLTP is poorly understood. Although there is evidence that particle fusion and the dissociation of lipid-poor or lipid-free apoA-I are involved (7,8), nothing is known about how the interaction of PLTP wi...

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Section: Methodsmentioning

confidence: 99%

The Mechanism of the Remodeling of High Density Lipoproteins by Phospholipid Transfer Protein

Settasatian¹,

Duong²,

Curtiss³

et al. 2001

Journal of Biological Chemistry

115

View full text Add to dashboard Cite

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“…1 is practically identical to that used by Huuskonen et al (22) for the modeling of PLTP. As described by these authors (22), most secondary structure elements are well conserved within this protein family. Compared with the human BPI sequence, PLTP contains four deletions, which occur in the surface loops con- necting ␤-strands and ␣-helices.…”

Section: Multiple Sequence Alignment and Building Of The Pltpmentioning

confidence: 69%

“…2A). The central part of the boomerang-shaped model structure of PLTP, containing the linker domain and the hypothetical lipid-binding pockets (22), is better conserved than the boomerang tips, which contain three of the four deletions. The N-terminal boomerang tip of BPI and LBP, consisting of loops 1, 2, and 4 and of helix ␣2 (as defined in Fig.…”

Section: Multiple Sequence Alignment and Building Of The Pltpmentioning

confidence: 99%

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A Hydrophobic Cluster at the Surface of the Human Plasma Phospholipid Transfer Protein Is Critical for Activity on High Density Lipoproteins

Desrumaux¹,

Labeur²,

Verhee

et al. 2001

Journal of Biological Chemistry

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The plasma phospholipid transfer protein (PLTP) belongs to the lipid transfer/lipopolysaccharide binding protein (LT/LBP) family, together with the cholesteryl ester transfer protein, the lipopolysaccharide binding protein (LBP) and the bactericidal permeability increasing protein (BPI). In the present study, we used the crystallographic data available for BPI to build a threedimensional model for PLTP. Multiple sequence alignment suggested that, in PLTP, a cluster of hydrophobic residues substitutes for a cluster of positively charged residues found on the surface of LBP and BPI, which is critical for interaction with lipopolysaccharides. According to the PLTP model, these hydrophobic residues are situated on an exposed hydrophobic patch at the N-terminal tip of the molecule. To assess the role of this hydrophobic cluster for the functional activity of PLTP, single point alanine mutants were engineered. Phospholipid transfer from liposomes to high density lipoprotein (HDL) by the W91A, F92A, and F93A PLTP mutants was drastically reduced, whereas their transfer activity toward very low density lipoprotein and low density lipoprotein did not change. The HDL size conversion activity of the mutants was reduced to the same extent as the PLTP transfer activity toward HDL. Based on these results, we propose that a functional solvent-exposed hydrophobic cluster in the PLTP molecule specifically contributes to the PLTP transfer activity on HDL substrates.Lipoprotein metabolism is regulated by the coordinated action of several factors, including lipolytic enzymes, lecithin: cholesterol acyltransferase, cholesteryl ester transfer protein (CETP) 1 and phospholipid transfer protein (PLTP) (1). Although PLTP was originally described as a mediator facilitating phospholipid transfer between lipoprotein particles, it is now recognized as a key factor in the intravascular metabolism and remodeling of HDL (2, 3). PLTP facilitates the transfer of different compounds, including phospholipids, lipopolysaccharides, ␣-tocopherol, and unesterified cholesterol, among lipoprotein classes and between lipoproteins and cells (2). Besides its transfer activity, PLTP enhances formation of largesized HDL and pre-␤ HDL, through apoAI release and HDL fusion (4). Although the physiological role of PLTP has not been completely defined yet, recent in vivo studies conducted with PLTP transgenic and knock-out mice strongly suggest that PLTP contributes to the control and regulation of HDL levels and to the generation of pre-␤ HDL, the initial acceptors of cellular cholesterol (3). PLTP belongs to the lipid transfer/lipopolysaccharide binding protein (LT/LBP) family, together with CETP, lipopolysaccharide binding protein (LBP), and bactericidal permeability increasing protein (BPI) (5). CETP transfers neutral lipids, i.e. cholesteryl esters and triglycerides between various lipoprotein fractions, and has limited phospholipid transfer activity (6). LBP and BPI bind and transfer bacterial endotoxins and lipopolysaccharides (LPS) and thus modulate the ho...

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“…4,5 The predicted model structure of PLTP consists of two lipid-binding pockets characterized by apolar residues, with an N-terminal pocket critical for PLTP transfer activity and a C-terminal pocket involved in lipid binding. 6,7 The initial physiological function ascribed to plasma PLTP was one of transfer of the phospholipids from triglyceriderich lipoproteins to high-density lipoproteins (HDL) during lipolysis. 8 Since then, animal and human studies have suggested that plasma PLTP level is an important factor in lipoprotein/lipid metabolism and atherosclerosis development.…”

Section: Introductionmentioning

confidence: 99%

Haplotypes in the phospholipid transfer protein gene are associated with obesity-related phenotypes: the Québec Family Study

et al. 2005

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BACKGROUND:The phospholipid transfer protein (PLTP) may play a role in body fat regulation. OBJECTIVE: To investigate the association between PLTP genetic variants and obesity-related phenotypes. METHODS: Two intronic variants, one in intron 1 (c.À87G4A) and the other in intron 12 (c.1175 þ 68T4G), were genotyped in 811 participants of the Québec Family Study. Nine obesity-related phenotypes were investigated, including body mass index (BMI), obesity (BMIZ30 kg/m 2 ), and waist circumference, percentage of fat, fat mass and fat-free mass measured by hydrostatic weighing as well as total, visceral and subcutaneous abdominal adipose tissue areas assessed by computed tomography. Single markers and haplotypes were tested for associations in family-based designs using the FBAT program. RESULTS: The SNP located in intron 1 showed significant associations with obesity, BMI, waist circumference and fat-free mass (Po0.05). The low-frequency allele (A allele) was associated with higher trait values, suggesting that the transmission of this allele is associated with an increased risk of being obese. Significant associations were observed between haplotypes and obesity, waist circumference, percentage of fat and fat-free mass (Po0.05). The transmission of the AT haplotype (frequency ¼ 0.180) was positively associated with obesity-related phenotypes. After sequencing the promoter and the coding regions of the PLTP gene, we were unable to identify a mutation that could replicate these results. CONCLUSION: Intronic variants of the PLTP gene are significantly associated with obesity-related phenotypes. Considering the number and the relevance of candidate genes surrounding the PLTP locus and the absence of missense polymorphisms in the coding region, the associations could be mediated by a second gene allele in linkage disequilibrium with the marker locus.

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Structure and phospholipid transfer activity of human PLTP: Analysis by molecular modelling and site-directed mutagenesis

Cited by 29 publications

References 0 publications

The Mechanism of the Remodeling of High Density Lipoproteins by Phospholipid Transfer Protein

The Mechanism of the Remodeling of High Density Lipoproteins by Phospholipid Transfer Protein

A Hydrophobic Cluster at the Surface of the Human Plasma Phospholipid Transfer Protein Is Critical for Activity on High Density Lipoproteins

Haplotypes in the phospholipid transfer protein gene are associated with obesity-related phenotypes: the Québec Family Study

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