Molecular crowding impacts the structure of apolipoprotein A-I with potential implications on in vivo metabolism and function.
The effect molecular crowding, defined as the volume exclusion exerted by one soluble inert molecule upon another soluble molecule, has on the structure and self-interaction of lipid-free apoA-I were explored. The influence of molecular crowding on lipid-free apoA-I oligomerization and internal dynamics has been analyzed using electron paramagnetic resonance (EPR) spectroscopy measurements of nitroxide spin label at selected positions throughout the protein sequence and at varying concentrations of the crowding agent Ficoll-70. The targeted positions include sites previously shown to be sensitive for detecting intermolecular interaction via spin-spin coupling. Circular dichroism was used to study secondary structural changes in lipid-free apoA-I imposed by increasing concentrations of the crowding agent. Crosslinking and SDS-PAGE gel analysis was employed to further characterize the role molecular crowding plays in inducing apoA-I oligomerization. It was concluded that the dynamic apoA-I structure and oligomeric state was altered in the presence of the crowding agent. It was also found that the C-terminal was slightly more sensitive to molecular crowding. Finally, the data described the region around residue 217 in the C-terminal domain of apoA-I as the most sensitive reporter of the crowding-induced self-association of apoA-I. The implications of this behavior to in vivo functionality are discussed. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 683-692, 2016.
Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden.
Jitka
J
Petrlova
Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616.
Silvia
S
Hilt
Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616.
Madhu
M
Budamagunta
Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden.
Joan
J
Domingo-Espín
Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden.|Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616.
John C
JC
Voss
Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden.
Jens O
JO
Lagerstedt
D016632:Apolipoprotein A-I / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005362:Ficoll / Q000737:chemistry*; D006801:Humans; D000072417:Protein Domains
D016632:Apolipoprotein A-I; D005362:Ficoll
CD; EPR; Ficoll-70; HDL; apoA-I; apolipoprotein A-I; high-density lipoprotein; molecular crowding