Crystal structure of axolotl (Ambystoma mexicanum) liver bile acid-binding protein bound to cholic and oleic acid.
The family of the liver bile acid-binding proteins (L-BABPs), formerly called liver basic fatty acid-binding proteins (Lb-FABPs) shares fold and sequence similarity with the paralogous liver fatty acid-binding proteins (L-FABPs) but has a different stoichiometry and specificity of ligand binding. This article describes the first X-ray structure of a member of the L-BABP family, axolotl (Ambystoma mexicanum) L-BABP, bound to two different ligands: cholic and oleic acid. The protein binds one molecule of oleic acid in a position that is significantly different from that of either of the two molecules that bind to rat liver FABP. The stoichiometry of binding of cholate is of two ligands per protein molecule, as observed in chicken L-BABP. The cholate molecule that binds buried most deeply into the internal cavity overlaps well with the analogous bound to chicken L-BABP, whereas the second molecule, which interacts with the first only through hydrophobic contacts, is more external and exposed to the solvent.
Biocrystallography Laboratory, Department of Science & Technology, University of Verona, Verona, Italy.
Stefano
S
Capaldi
Mara
M
Guariento
Massimiliano
M
Perduca
Santiago M
SM
Di Pietro
José A
JA
Santomé
Hugo L
HL
Monaco
D000557:Ambystoma; D000595:Amino Acid Sequence; D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D019826:Cholic Acid / Q000378:metabolism*; D018360:Crystallography, X-Ray; D050556:Fatty Acid-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D019301:Oleic Acid / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D051381:Rats; D012996:Solutions
D001647:Bile Acids and Salts; D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; D008562:Membrane Glycoproteins; D012996:Solutions; C037643:bile acid binding proteins; D019301:Oleic Acid; D019826:Cholic Acid