Conformational changes of chicken liver bile acid-binding protein bound to anionic lipid membrane are coupled to the lipid phase transitions.
Chicken liver bile acid-binding protein (L-BABP) binds to anionic lipid membranes by electrostatic interactions and acquires a partly folded state [Nolan, V., Perduca, M., Monaco, H., Maggio, B. and Montich, G. G. (2003) Biochim. Biophys. Acta 1611, 98-106]. We studied the infrared amide I' band of L-BABP bound to dipalmitoylphosphatidylglycerol (DPPG), dimyristoylphosphatidylglycerol (DMPG) and palmitoyloleoylphosphatidylglycerol (POPG) in the range of 7 to 60 degrees C. Besides, the thermotrophic behaviour of DPPG and DMPG was studied in the absence and in the presence of bound-protein by differential scanning calorimetry (DSC) and infrared spectra of the stretching vibration of methylene and carbonyl groups. When L-BABP was bound to lipid membranes in the liquid-crystalline state (POPG between 7 and 30 degrees C) acquired a more unfolded conformation that in membranes in the gel state (DPPG between 7 and 30 degrees C). Nevertheless, this conformational change of the protein in DMPG did not occur at the temperature of the lipid gel to liquid-crystalline phase transition detected by infrared spectroscopy. Instead, the degree of unfolding in the protein was coincident with a phase transition in DMPG that occurs with heat absorption and without change in the lipid order.
Decca
María Belén
MB
Centro de Investigaciones en Química Biológica de Córdoba, UNC-CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, República Argentina.
Perduca
Massimiliano
M
Monaco
Hugo L
HL
Montich
Guillermo G
GG
D000818:Animals; D002152:Calorimetry, Differential Scanning; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D002645:Chickens / Q000235:genetics*; D008051:Lipid Bilayers / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D044367:Phase Transition; D010715:Phosphatidylglycerols / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D013696:Temperature
D002352:Carrier Proteins; D008051:Lipid Bilayers; D008562:Membrane Glycoproteins; D010715:Phosphatidylglycerols; C037643:bile acid binding proteins; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; C002773:dimyristoylphosphatidylglycerol; C030345:1,2-dipalmitoylphosphatidylglycerol