Structure of the human-heart fatty-acid-binding protein 3 in complex with the fluorescent probe 1-anilinonaphthalene-8-sulphonic acid

Abstract

Heart-type fatty-acid-binding protein (FABP3), which is a cytosolic protein abundantly found in cardiomyocytes, plays a role in trafficking fatty acids throughout cellular compartments by reversibly binding intracellular fatty acids with relatively high affinity. The fluorescent probe 1-anilinonaphthalene-8-sulfonate (ANS) is extensively utilized for examining the interaction of ligands with fatty-acid-binding proteins. The X-ray structure of FABP3 was determined in the presence of ANS and revealed the detailed ANS-binding mechanism. Furthermore, four water molecules were clearly identified in the binding cavity. Through these water molecules, the bound ANS molecule forms indirect hydrogen-bond interactions with FABP3. The adipocyte-type fatty-acid-binding protein (FABP4) exhibits 67% sequence identity with FABP3 and its crystal structure is almost the same as that of FABP3. However, FABP4 can bind with a higher affinity to ANS than FABP3. To understand the difference in their ligand specificities, a structural comparison was performed between FABP3-ANS and FABP4-ANS complexes. The result revealed that the orientation of ANS binding to FABP3 is completely opposite to that of ANS binding to FABP4, and the substitution of valine in FABP4 to leucine in FABP3 may result in greater steric hindrance between the side-chain of Leu115 and the aniline ring of ANS.

Fatty Acid Binding Proteins Expressed at the Human Blood–Brain Barrier Bind Drugs in an Isoform-Specific Manner

“…For FABP3, 4 and 5, the magnitude of the entropy change on binding to ANS was hFABP5>FABP3>FABP4. These differences in thermodynamic signatures between the FABPs in this subgroup suggest ANS may bind differently across hFABP3, 4 and 5, as has been suggested by structural studies where ANS was reported to bind to hFABP3 and mFABP4 in opposite orientations (36,42).…”

“…FABP1 can bind to two fatty acids (34); FABP2 binds fatty acids in a bent conformation (35) and FABP3, 4 and 5 bind to fatty acids in a U shape configuration (36)(37)(38). This conformation-specific binding appears to be associated with differences in the affinities of FABP binding to specific fatty acids (39).…”

Effects of salts on the interaction of 8-anilinonaphthalene 1-sulphonate and thermolysin

“…The binding sites for ANS were determined in some proteins. 40,41) The elucidation of the binding site of thermolysin for ANS is the next research subject.…”

Development of protein seed crystals reinforced with high-strength hydrogels

“…28,29 Purity was verified using sodium dodecyl sulfate polyacrylamide electrophoresis. Chicken eggwhite lysozyme (LZM) was purchased from Seikagaku Kogyo and used without further purification.…”