Surface lysine residues modulate the collisional transfer of fatty acid from adipocyte fatty acid binding protein to membranes

Herr, Fiona; Matarese, Valerie; Bernlohr, David A.; Storch, Judith

doi:10.1021/bi00037a023

Cited by 71 publications

(73 citation statements)

References 34 publications

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“…These results suggest that in general, stability of the apo-or holoprotein is not coupled to ligand affinity. Consistent with this interpretation, Herr et al (8) have recently demonstrated with chemically modified ALBP that when all surface lysine residues are acetylated, the stability of the protein is affected (destabilized) while the affinity is unaltered. Similarly, in studies of cellular retinoic acid-binding protein 1 (25), substitution mutations of critical arginine residues rendered the protein unable to bind retinoic acid but stabilized the molecule to thermal denaturation.…”

Section: Discussionmentioning

confidence: 72%

Biochemical and Crystallographic Analyses of a Portal Mutant of the Adipocyte Lipid-binding Protein

Ory

Kane

Simpson

et al. 1997

Journal of Biological Chemistry

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A number of crystallographic studies of the adipocyte lipid-binding protein have established that the fatty acid-binding site is within an internalized water-filled cavity. The same studies have also suggested the existence of a region physically distinct from the fatty acid-binding site which connects the cavity of the protein with the external solvent, hereafter referred to as the portal. In an effort to examine the portal region, we have used site-directed mutagenesis to introduce the mutations V32D/F57H into the murine ALBP cDNA. Mutant protein has been isolated, crystallized, and its stability and binding properties studied by biochemical methods. As assessed by guanidine-HCl denaturation, the mutant form exhibited a slight overall destabilization relative to the wild-type protein under both acid and alkaline conditions. Accessibility to the cavity in both the mutant and wild-type proteins was observed by stopped-flow analysis of the modification of a cavity residue, Cys 117 , by the sulfhydryl reactive agent 5,5 -dithiobis(2-nitrobenzoic acid) at pH 8.5. Cys 117 of V32D/F57H ALBP was modified 7-fold faster than the wild-type protein. The ligand binding properties of both the V32D/F57H mutant and wild-type proteins were analyzed using a fluorescent probe at pH 6.0 and 8.0. The apparent dissociation constants for 1-anilinonaphthalene-8-sulfonic acid were approximately 9 -10-fold greater than the wild-type protein, independent of pH. In addition, there is a 6-fold increase in the K d for oleic acid for the portal mutant relative to the wild-type at pH 8.0. To study the effect of pH on the double mutant, it was crystallized and analyzed in two distinct space groups at pH 4.5 and 6.4. While in general the differences in the overall main chain conformations are negligible, changes were observed in the crystallographic structures near the site of the mutations. At both pH values, the mutant side chains are positioned somewhat differently than in wild-type protein. To ensure that the mutations had not altered ionic conditions near the binding site, the crystallographic coordinates were used to monitor the electrostatic potentials from the head group site to the positions near the portal region. The differences in the electrostatic potentials were small in all regions, and did not explain the differences in ligand affinity. We present these results within the context of fatty acid binding and suggest lipid association is more complex than that described within a single equilibrium event.

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Section: Discussionmentioning

confidence: 72%

Biochemical and Crystallographic Analyses of a Portal Mutant of the Adipocyte Lipid-binding Protein

Ory

Kane

Simpson

et al. 1997

Journal of Biological Chemistry

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“…Many forms of FABP (e.g., from heart, adipocyte, and intestine) transfer fatty acids to and from membranes during brief collisional encounters (7,10,12,13,31). This process involves an interaction between a positively charged region of the binding protein and negative charges on the membrane surface, resulting in a conformational change that permits direct transfer of fatty acid between the protein binding site and the membrane (5,7,10,11,30). We will refer to this FABP class as being membrane active.…”

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confidence: 99%

Transfer of fatty acids between intracellular membranes: roles of soluble binding proteins, distance, and time

Weisiger

Zucker

2002

American Journal of Physiology-Gastrointestinal and Liver Physi

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Soluble fatty acid binding proteins (FABPs) are thought to facilitate exchange of fatty acids between intracellular membranes. Although many FABP variants have been described, they fall into two general classes. "Membrane-active" FABPs exchange fatty acids with membranes during transient collisions with the membrane surface, whereas "membrane-inactive" FABPs do not. We used modeling of fatty acid transport between two planar membranes to examine the hypothesis that these two classes catalyze different steps in intracellular fatty acid transport. In the absence of FABP, the steady-state flux of fatty acid from the donor to the acceptor membrane depends on membrane separation distance (d) approaching a maximum value (J max) as d approaches zero. Jmax is one-half the rate of dissociation of fatty acid from the donor membrane, indicating that newly dissociated fatty acid has a 50% chance of successfully reaching the acceptor membrane before rebinding to the donor membrane. For larger membrane separations, successful transfer becomes less likely as diffusional concentration gradients develop. The mean diffusional excursion of the fatty acid into the water phase (d m) defines this transition. For dϽ Ͻd m, dissociation from the membrane is rate limiting, whereas for dϾ Ͼd m, aqueous diffusion is rate limiting. All forms of FABP increase d m by reducing the rate of rebinding to the donor membrane, thus maintaining J max over larger membrane separations. Membrane-active FABPs further increase J max by catalyzing the rate of dissociation of fatty acids from the donor membrane, although frequent membrane interactions would be expected to reduce their diffusional mobility through a membrane-rich cytoplasm. Individual FABPs may have evolved to match the membrane separations and densities found in specific cell lines.

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“…A FABP has been proposed to be involved in the intracellular trafficking and targeting of fatty acids (3,4). In vitro studies have indicated that the transfer of fatty acids from AFABP to vesicles occurs during direct collisional interactions between the protein and acceptor membranes; however, the fatty acid transfer properties of KFABP have not been reported.…”

mentioning

confidence: 99%

“…R e c o mbinant murine AFABP and KFABP were expressed in Escherichia coli h o s t strain BL21 (DE3) and purified using gel filtration, ion exchange, and delipidation chromatography, as previously described (4,15). The rate of transfer of 12-(9-anthroyloxy)oleate (12AO) from AFABP and KFABP to small unilamellar vesicles (SUVs) was determined using a previously detailed resonance energy transfer assay (4,15). Transfer was monitored at 25°C in 40 mmol/l Tr i s -1 0 0 mmol/l NaCl, pH 7.4.…”

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confidence: 99%

Adipocyte metabolism in adipocyte fatty acid binding protein knockout mice (aP2-/-) after short-term high-fat feeding: functional compensation by the keratinocyte [correction of keritinocyte] fatty acid binding protein.

et al. 2000

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Mice null for adipocyte fatty acid binding protein ( A FABP) compensate by increasing expression of keratinocyte fatty acid binding protein (KFABP) (Hotamisligil et al. S c i e n c e 274:1377-1379, 1996). In the present s t u d y, AFABP knockout (KO) and wild-type (WT) mice became equally obese on a high-fat diet, as judged by fat pad weights, adipocyte size, and body composition analysis. High-fat feeding led to moderate insulin resistance in both WT and AFABP knockout mice, as indicated by an ~2-fold increase in plasma insulin. H o w e v e r, in the high fat-fed mice, plasma glucose levels were ~15% lower in the AFABP-KO mice. Adipocytes isolated from AFABP-KO and WT mice fed high-or low-fat diets exhibited similar rates of basal and norepinephrine-stimulated lipolysis and insulinstimulated rates of glucose conversion to fatty acids and glyceride-glycerol. However, basal glucose conversion to fatty acids was higher in adipocytes of AFA B P -KO mice. Adipocyte tumor necrosis factor-r e l e a s e was similarly increased by high-fat diet-induced obesity in both WT and AFABP-KO mice. As assessed by We s tern blot analysis, the level of KFABP protein in A FABP-KOs was ~40% of the level of AFABP in WT controls. The binding affinities of KFABP for longchain fatty acids were 2-to 4-fold higher than those of A FA B P, but the relative affinities for different fatty acids were similar. As for AFA B P, the rate of fatty acid transfer from KFABP to model phospholipid vesicles was increased with acceptor membrane concentration and by inclusion of acidic phospholipids, indicating a similar mechanism of transfer. We conclude KFABP can functionally compensate for the absence of AFA B P, resulting in no major alterations in adipocyte metabolism or fat accumulation in response to short-term feeding of high-fat diets that result in moderate hyperinsulinemia. D i a b e t e s 4 9 :9 0 4-911, 2000

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Surface lysine residues modulate the collisional transfer of fatty acid from adipocyte fatty acid binding protein to membranes

Cited by 71 publications

References 34 publications

Biochemical and Crystallographic Analyses of a Portal Mutant of the Adipocyte Lipid-binding Protein

Biochemical and Crystallographic Analyses of a Portal Mutant of the Adipocyte Lipid-binding Protein

Transfer of fatty acids between intracellular membranes: roles of soluble binding proteins, distance, and time

Adipocyte metabolism in adipocyte fatty acid binding protein knockout mice (aP2-/-) after short-term high-fat feeding: functional compensation by the keratinocyte [correction of keritinocyte] fatty acid binding protein.

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